Android RecyclerView 使用完全解析体验艺术般的控件

迷南。 2022-08-21 05:51 178阅读 0赞

> > 转载请标明出处：  
> > [http://blog.csdn.net/lmj623565791/article/details/45059587][http_blog.csdn.net_lmj623565791_article_details_45059587]；  
> > 本文出自:[【张鸿洋的博客】][Link 1]
> 
> ### 概述 ###
> 
> RecyclerView出现已经有一段时间了，相信大家肯定不陌生了，大家可以通过导入support-v7对其进行使用。  
> 据官方的介绍，该控件用于在有限的窗口中展示大量数据集，其实这样功能的控件我们并不陌生，例如：ListView、GridView。
> 
> 那么有了ListView、GridView为什么还需要RecyclerView这样的控件呢？整体上看RecyclerView架构，提供了一种插拔式的体验，高度的解耦，异常的灵活，通过设置它提供的不同LayoutManager，ItemDecoration , ItemAnimator实现令人瞠目的效果。
> 
> * 你想要控制其显示的方式，请通过布局管理器LayoutManager
> * 你想要控制Item间的间隔（可绘制），请通过ItemDecoration
> * 你想要控制Item增删的动画，请通过ItemAnimator
> * 你想要控制点击、长按事件，请自己写（擦，这点尼玛。）
> 
> ### 基本使用 ###
> 
> 鉴于我们对于ListView的使用特别的熟悉，对比下RecyclerView的使用代码：
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">mRecyclerView = findView(R.id.id_recyclerview);
> //设置布局管理器
> mRecyclerView.setLayoutManager(layout);
> //设置adapter
> mRecyclerView.setAdapter(adapter)
> //设置Item增加、移除动画
> mRecyclerView.setItemAnimator(new DefaultItemAnimator());
> //添加分割线
> mRecyclerView.addItemDecoration(new DividerItemDecoration(
> getActivity(), DividerItemDecoration.HORIZONTAL_LIST));</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul>
> 
> ok，相比较于ListView的代码，ListView可能只需要去设置一个adapter就能正常使用了。而RecyclerView基本需要上面一系列的步骤，那么为什么会添加这么多的步骤呢？
> 
> 那么就必须解释下RecyclerView的这个名字了，从它类名上看，RecyclerView代表的意义是，我只管Recycler View，也就是说RecyclerView只管回收与复用View，其他的你可以自己去设置。可以看出其高度的解耦，给予你充分的定制自由（所以你才可以轻松的通过这个控件实现ListView,GirdView，瀑布流等效果）。
> 
> ### Just like ListView ###
> 
> * Activity
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">package com.zhy.sample.demo_recyclerview;
> 
> import java.util.ArrayList;
> import java.util.List;
> 
> import android.os.Bundle;
> import android.support.v7.app.ActionBarActivity;
> import android.support.v7.widget.LinearLayoutManager;
> import android.support.v7.widget.RecyclerView;
> import android.support.v7.widget.RecyclerView.ViewHolder;
> import android.view.LayoutInflater;
> import android.view.View;
> import android.view.ViewGroup;
> import android.widget.TextView;
> 
> public class HomeActivity extends ActionBarActivity
> {
> 
> private RecyclerView mRecyclerView;
> private List<String> mDatas;
> private HomeAdapter mAdapter;
> 
> @Override
> protected void onCreate(Bundle savedInstanceState)
> {
> super.onCreate(savedInstanceState);
> setContentView(R.layout.activity_single_recyclerview);
> 
> initData();
> mRecyclerView = (RecyclerView) findViewById(R.id.id_recyclerview);
> mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
> mRecyclerView.setAdapter(mAdapter = new HomeAdapter());
> 
> }
> 
> protected void initData()
> {
> mDatas = new ArrayList<String>();
> for (int i = 'A'; i < 'z'; i++)
> {
> mDatas.add("" + (char) i);
> }
> }
> 
> class HomeAdapter extends RecyclerView.Adapter<HomeAdapter.MyViewHolder>
> {
> 
> @Override
> public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType)
> {
> MyViewHolder holder = new MyViewHolder(LayoutInflater.from(
> HomeActivity.this).inflate(R.layout.item_home, parent,
> false));
> return holder;
> }
> 
> @Override
> public void onBindViewHolder(MyViewHolder holder, int position)
> {
> holder.tv.setText(mDatas.get(position));
> }
> 
> @Override
> public int getItemCount()
> {
> return mDatas.size();
> }
> 
> class MyViewHolder extends ViewHolder
> {
> 
> TextView tv;
> 
> public MyViewHolder(View view)
> {
> super(view);
> tv = (TextView) view.findViewById(R.id.id_num);
> }
> }
> }
> 
> }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li><li style="box-sizing: border-box; padding: 0px 5px;">64</li><li style="box-sizing: border-box; padding: 0px 5px;">65</li><li style="box-sizing: border-box; padding: 0px 5px;">66</li><li style="box-sizing: border-box; padding: 0px 5px;">67</li><li style="box-sizing: border-box; padding: 0px 5px;">68</li><li style="box-sizing: border-box; padding: 0px 5px;">69</li><li style="box-sizing: border-box; padding: 0px 5px;">70</li><li style="box-sizing: border-box; padding: 0px 5px;">71</li><li style="box-sizing: border-box; padding: 0px 5px;">72</li><li style="box-sizing: border-box; padding: 0px 5px;">73</li><li style="box-sizing: border-box; padding: 0px 5px;">74</li><li style="box-sizing: border-box; padding: 0px 5px;">75</li><li style="box-sizing: border-box; padding: 0px 5px;">76</li><li style="box-sizing: border-box; padding: 0px 5px;">77</li><li style="box-sizing: border-box; padding: 0px 5px;">78</li><li style="box-sizing: border-box; padding: 0px 5px;">79</li><li style="box-sizing: border-box; padding: 0px 5px;">80</li><li style="box-sizing: border-box; padding: 0px 5px;">81</li><li style="box-sizing: border-box; padding: 0px 5px;">82</li></ul>
> 
> * Activity的布局文件
> 
> <code class="language-xml hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
> xmlns:tools="http://schemas.android.com/tools"
> android:layout_width="match_parent"
> android:layout_height="match_parent" >
> 
> <android.support.v7.widget.RecyclerView
> android:id="@+id/id_recyclerview"
> android:divider="#ffff0000"
> android:dividerHeight="10dp"
> android:layout_width="match_parent"
> android:layout_height="match_parent" />
> 
> </RelativeLayout></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li></ul>
> 
> * Item的布局文件
> 
> <code class="language-xml hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><?xml version="1.0" encoding="utf-8"?>
> <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
> android:layout_width="match_parent"
> android:background="#44ff0000"
> android:layout_height="wrap_content" >
> 
> <TextView
> android:id="@+id/id_num"
> android:layout_width="match_parent"
> android:layout_height="50dp"
> android:gravity="center"
> android:text="1" />
> </FrameLayout></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li></ul>
> 
> 这么看起来用法与ListView的代码基本一致哈~~  
> 看下效果图：
> 
> ![20150415145840351][]
> 
> 看起来好丑，Item间应该有个分割线，当你去找时，你会发现RecyclerView并没有支持divider这样的属性。那么怎么办，你可以给Item的布局去设置margin，当然了这种方式不够优雅，我们文章开始说了，我们可以自由的去定制它，当然我们的分割线也是可以定制的。
> 
> ### ItemDecoration ###
> 
> 我们可以通过该方法添加分割线：  
> `mRecyclerView.addItemDecoration()`  
> 该方法的参数为RecyclerView.ItemDecoration，该类为抽象类，官方目前并没有提供默认的实现类（我觉得最好能提供几个）。  
> 该类的源码：
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">public static abstract class ItemDecoration {
> 
> public void onDraw(Canvas c, RecyclerView parent, State state) {
> onDraw(c, parent);
> }
> 
> 
> public void onDrawOver(Canvas c, RecyclerView parent, State state) {
> onDrawOver(c, parent);
> }
> 
> public void getItemOffsets(Rect outRect, View view, RecyclerView parent, State state) {
> getItemOffsets(outRect, ((LayoutParams) view.getLayoutParams()).getViewLayoutPosition(),
> parent);
> }
> 
> @Deprecated
> public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
> outRect.set(0, 0, 0, 0);
> }
> </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li></ul>
> 
> 当我们调用`mRecyclerView.addItemDecoration()`方法添加decoration的时候，RecyclerView在绘制的时候，去会绘制decorator，即调用该类的onDraw和onDrawOver方法，
> 
> * onDraw方法先于drawChildren
> * onDrawOver在drawChildren之后，一般我们选择复写其中一个即可。
> * getItemOffsets 可以通过outRect.set()为每个Item设置一定的偏移量，主要用于绘制Decorator。
> 
> 接下来我们看一个`RecyclerView.ItemDecoration`的实现类，该类很好的实现了RecyclerView添加分割线（当使用LayoutManager为LinearLayoutManager时）。  
> 该类参考自：[DividerItemDecoration][]
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">
> package com.zhy.sample.demo_recyclerview;
> 
> /*
> * Copyright (C) 2014 The Android Open Source Project
> *
> * Licensed under the Apache License, Version 2.0 (the "License");
> * limitations under the License.
> */
> 
> import android.content.Context;
> import android.content.res.TypedArray;
> import android.graphics.Canvas;
> import android.graphics.Rect;
> import android.graphics.drawable.Drawable;
> import android.support.v7.widget.LinearLayoutManager;
> import android.support.v7.widget.RecyclerView;
> import android.support.v7.widget.RecyclerView.State;
> import android.util.Log;
> import android.view.View;
> 
> 
> /**
> * This class is from the v7 samples of the Android SDK. It's not by me!
> * 
> * See the license above for details.
> */
> public class DividerItemDecoration extends RecyclerView.ItemDecoration {
> 
> private static final int[] ATTRS = new int[]{
> android.R.attr.listDivider
> };
> 
> public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;
> 
> public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;
> 
> private Drawable mDivider;
> 
> private int mOrientation;
> 
> public DividerItemDecoration(Context context, int orientation) {
> final TypedArray a = context.obtainStyledAttributes(ATTRS);
> mDivider = a.getDrawable(0);
> a.recycle();
> setOrientation(orientation);
> }
> 
> public void setOrientation(int orientation) {
> if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
> throw new IllegalArgumentException("invalid orientation");
> }
> mOrientation = orientation;
> }
> 
> @Override
> public void onDraw(Canvas c, RecyclerView parent) {
> Log.v("recyclerview - itemdecoration", "onDraw()");
> 
> if (mOrientation == VERTICAL_LIST) {
> drawVertical(c, parent);
> } else {
> drawHorizontal(c, parent);
> }
> 
> }
> 
> 
> public void drawVertical(Canvas c, RecyclerView parent) {
> final int left = parent.getPaddingLeft();
> final int right = parent.getWidth() - parent.getPaddingRight();
> 
> final int childCount = parent.getChildCount();
> for (int i = 0; i < childCount; i++) {
> final View child = parent.getChildAt(i);
> android.support.v7.widget.RecyclerView v = new android.support.v7.widget.RecyclerView(parent.getContext());
> final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
> .getLayoutParams();
> final int top = child.getBottom() + params.bottomMargin;
> final int bottom = top + mDivider.getIntrinsicHeight();
> mDivider.setBounds(left, top, right, bottom);
> mDivider.draw(c);
> }
> }
> 
> public void drawHorizontal(Canvas c, RecyclerView parent) {
> final int top = parent.getPaddingTop();
> final int bottom = parent.getHeight() - parent.getPaddingBottom();
> 
> final int childCount = parent.getChildCount();
> for (int i = 0; i < childCount; i++) {
> final View child = parent.getChildAt(i);
> final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
> .getLayoutParams();
> final int left = child.getRight() + params.rightMargin;
> final int right = left + mDivider.getIntrinsicHeight();
> mDivider.setBounds(left, top, right, bottom);
> mDivider.draw(c);
> }
> }
> 
> @Override
> public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
> if (mOrientation == VERTICAL_LIST) {
> outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
> } else {
> outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
> }
> }
> }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li><li style="box-sizing: border-box; padding: 0px 5px;">64</li><li style="box-sizing: border-box; padding: 0px 5px;">65</li><li style="box-sizing: border-box; padding: 0px 5px;">66</li><li style="box-sizing: border-box; padding: 0px 5px;">67</li><li style="box-sizing: border-box; padding: 0px 5px;">68</li><li style="box-sizing: border-box; padding: 0px 5px;">69</li><li style="box-sizing: border-box; padding: 0px 5px;">70</li><li style="box-sizing: border-box; padding: 0px 5px;">71</li><li style="box-sizing: border-box; padding: 0px 5px;">72</li><li style="box-sizing: border-box; padding: 0px 5px;">73</li><li style="box-sizing: border-box; padding: 0px 5px;">74</li><li style="box-sizing: border-box; padding: 0px 5px;">75</li><li style="box-sizing: border-box; padding: 0px 5px;">76</li><li style="box-sizing: border-box; padding: 0px 5px;">77</li><li style="box-sizing: border-box; padding: 0px 5px;">78</li><li style="box-sizing: border-box; padding: 0px 5px;">79</li><li style="box-sizing: border-box; padding: 0px 5px;">80</li><li style="box-sizing: border-box; padding: 0px 5px;">81</li><li style="box-sizing: border-box; padding: 0px 5px;">82</li><li style="box-sizing: border-box; padding: 0px 5px;">83</li><li style="box-sizing: border-box; padding: 0px 5px;">84</li><li style="box-sizing: border-box; padding: 0px 5px;">85</li><li style="box-sizing: border-box; padding: 0px 5px;">86</li><li style="box-sizing: border-box; padding: 0px 5px;">87</li><li style="box-sizing: border-box; padding: 0px 5px;">88</li><li style="box-sizing: border-box; padding: 0px 5px;">89</li><li style="box-sizing: border-box; padding: 0px 5px;">90</li><li style="box-sizing: border-box; padding: 0px 5px;">91</li><li style="box-sizing: border-box; padding: 0px 5px;">92</li><li style="box-sizing: border-box; padding: 0px 5px;">93</li><li style="box-sizing: border-box; padding: 0px 5px;">94</li><li style="box-sizing: border-box; padding: 0px 5px;">95</li><li style="box-sizing: border-box; padding: 0px 5px;">96</li><li style="box-sizing: border-box; padding: 0px 5px;">97</li><li style="box-sizing: border-box; padding: 0px 5px;">98</li><li style="box-sizing: border-box; padding: 0px 5px;">99</li><li style="box-sizing: border-box; padding: 0px 5px;">100</li><li style="box-sizing: border-box; padding: 0px 5px;">101</li><li style="box-sizing: border-box; padding: 0px 5px;">102</li><li style="box-sizing: border-box; padding: 0px 5px;">103</li><li style="box-sizing: border-box; padding: 0px 5px;">104</li><li style="box-sizing: border-box; padding: 0px 5px;">105</li><li style="box-sizing: border-box; padding: 0px 5px;">106</li><li style="box-sizing: border-box; padding: 0px 5px;">107</li><li style="box-sizing: border-box; padding: 0px 5px;">108</li><li style="box-sizing: border-box; padding: 0px 5px;">109</li><li style="box-sizing: border-box; padding: 0px 5px;">110</li></ul>
> 
> 该实现类可以看到通过读取系统主题中的 `android.R.attr.listDivider`作为Item间的分割线，并且支持横向和纵向。如果你不清楚它是怎么做到的读取系统的属性用于自身，请参考我的另一篇博文：[Android 深入理解Android中的自定义属性][DividerItemDecoration]
> 
> 获取到listDivider以后，该属性的值是个Drawable，在`getItemOffsets`中，outRect去设置了绘制的范围。onDraw中实现了真正的绘制。
> 
> 我们在原来的代码中添加一句：
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">mRecyclerView.addItemDecoration(new DividerItemDecoration(this,
> DividerItemDecoration.VERTICAL_LIST));</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>
> 
> ok，现在再运行，就可以看到分割线的效果了。
> 
> ![20150415145931083][]
> 
> 该分割线是系统默认的，你可以在theme.xml中找到该属性的使用情况。那么，使用系统的listDivider有什么好处呢？就是方便我们去随意的改变，该属性我们可以直接声明在：
> 
> <code class="language-xml hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"> 
> <style name="AppTheme" parent="AppBaseTheme">
> <item name="android:listDivider">@drawable/divider_bg</item> 
> </style></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>
> 
> 然后自己写个drawable即可，下面我们换一种分隔符：
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><?xml version="1.0" encoding="utf-8"?>
> <shape xmlns:android="http://schemas.android.com/apk/res/android"
> android:shape="rectangle" >
> 
> <gradient
> android:centerColor="#ff00ff00"
> android:endColor="#ff0000ff"
> android:startColor="#ffff0000"
> android:type="linear" />
> <size android:height="4dp"/>
> 
> </shape></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>
> 
> 现在的样子是：
> 
> ![20150415151013289][]
> 
> 当然了，你可以根据自己的需求，去随意的绘制，反正是画出来的，随便玩~~
> 
> ok，看到这，你可能觉得，这玩意真尼玛麻烦，完全不能比拟的心爱的ListView。那么继续看。
> 
> ### LayoutManager ###
> 
> 好了，上面实现了类似ListView样子的Demo，通过使用其默认的LinearLayoutManager。
> 
> RecyclerView.LayoutManager吧，这是一个抽象类，好在系统提供了3个实现类：
> 
> 1. LinearLayoutManager 现行管理器，支持横向、纵向。
> 2. GridLayoutManager 网格布局管理器
> 3. StaggeredGridLayoutManager 瀑布就式布局管理器
> 
> 上面我们已经初步体验了下LinearLayoutManager，接下来看GridLayoutManager。
> 
> * GridLayoutManager
> 
> 我们尝试去实现类似GridView，秒秒钟的事情：
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">//mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
> mRecyclerView.setLayoutManager(new GridLayoutManager(this,4));</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>
> 
> 只需要修改LayoutManager即可，还是很nice的。
> 
> 当然了，改为GridLayoutManager以后，对于分割线，前面的DividerItemDecoration就不适用了，主要是因为它在绘制的时候，比如水平线，针对每个child的取值为：
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">final int left = parent.getPaddingLeft();
> final int right = parent.getWidth() - parent.getPaddingRight();</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>
> 
> 因为每个Item一行，这样是没问题的。而GridLayoutManager时，一行有多个childItem，这样就多次绘制了，并且GridLayoutManager时，Item如果为最后一列（则右边无间隔线）或者为最后一行（底部无分割线）。
> 
> 针对上述，我们编写了`DividerGridItemDecoration`。
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">package com.zhy.sample.demo_recyclerview;
> 
> import android.content.Context;
> import android.content.res.TypedArray;
> import android.graphics.Canvas;
> import android.graphics.Rect;
> import android.graphics.drawable.Drawable;
> import android.support.v7.widget.GridLayoutManager;
> import android.support.v7.widget.RecyclerView;
> import android.support.v7.widget.RecyclerView.LayoutManager;
> import android.support.v7.widget.RecyclerView.State;
> import android.support.v7.widget.StaggeredGridLayoutManager;
> import android.view.View;
> 
> /**
> * 
> * @author zhy
> * 
> */
> public class DividerGridItemDecoration extends RecyclerView.ItemDecoration
> {
> 
> private static final int[] ATTRS = new int[] { android.R.attr.listDivider };
> private Drawable mDivider;
> 
> public DividerGridItemDecoration(Context context)
> {
> final TypedArray a = context.obtainStyledAttributes(ATTRS);
> mDivider = a.getDrawable(0);
> a.recycle();
> }
> 
> @Override
> public void onDraw(Canvas c, RecyclerView parent, State state)
> {
> 
> drawHorizontal(c, parent);
> drawVertical(c, parent);
> 
> }
> 
> private int getSpanCount(RecyclerView parent)
> {
> // 列数
> int spanCount = -1;
> LayoutManager layoutManager = parent.getLayoutManager();
> if (layoutManager instanceof GridLayoutManager)
> {
> 
> spanCount = ((GridLayoutManager) layoutManager).getSpanCount();
> } else if (layoutManager instanceof StaggeredGridLayoutManager)
> {
> spanCount = ((StaggeredGridLayoutManager) layoutManager)
> .getSpanCount();
> }
> return spanCount;
> }
> 
> public void drawHorizontal(Canvas c, RecyclerView parent)
> {
> int childCount = parent.getChildCount();
> for (int i = 0; i < childCount; i++)
> {
> final View child = parent.getChildAt(i);
> final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
> .getLayoutParams();
> final int left = child.getLeft() - params.leftMargin;
> final int right = child.getRight() + params.rightMargin
> + mDivider.getIntrinsicWidth();
> final int top = child.getBottom() + params.bottomMargin;
> final int bottom = top + mDivider.getIntrinsicHeight();
> mDivider.setBounds(left, top, right, bottom);
> mDivider.draw(c);
> }
> }
> 
> public void drawVertical(Canvas c, RecyclerView parent)
> {
> final int childCount = parent.getChildCount();
> for (int i = 0; i < childCount; i++)
> {
> final View child = parent.getChildAt(i);
> 
> final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
> .getLayoutParams();
> final int top = child.getTop() - params.topMargin;
> final int bottom = child.getBottom() + params.bottomMargin;
> final int left = child.getRight() + params.rightMargin;
> final int right = left + mDivider.getIntrinsicWidth();
> 
> mDivider.setBounds(left, top, right, bottom);
> mDivider.draw(c);
> }
> }
> 
> private boolean isLastColum(RecyclerView parent, int pos, int spanCount,
> int childCount)
> {
> LayoutManager layoutManager = parent.getLayoutManager();
> if (layoutManager instanceof GridLayoutManager)
> {
> if ((pos + 1) % spanCount == 0)// 如果是最后一列，则不需要绘制右边
> {
> return true;
> }
> } else if (layoutManager instanceof StaggeredGridLayoutManager)
> {
> int orientation = ((StaggeredGridLayoutManager) layoutManager)
> .getOrientation();
> if (orientation == StaggeredGridLayoutManager.VERTICAL)
> {
> if ((pos + 1) % spanCount == 0)// 如果是最后一列，则不需要绘制右边
> {
> return true;
> }
> } else
> {
> childCount = childCount - childCount % spanCount;
> if (pos >= childCount)// 如果是最后一列，则不需要绘制右边
> return true;
> }
> }
> return false;
> }
> 
> private boolean isLastRaw(RecyclerView parent, int pos, int spanCount,
> int childCount)
> {
> LayoutManager layoutManager = parent.getLayoutManager();
> if (layoutManager instanceof GridLayoutManager)
> {
> childCount = childCount - childCount % spanCount;
> if (pos >= childCount)// 如果是最后一行，则不需要绘制底部
> return true;
> } else if (layoutManager instanceof StaggeredGridLayoutManager)
> {
> int orientation = ((StaggeredGridLayoutManager) layoutManager)
> .getOrientation();
> // StaggeredGridLayoutManager 且纵向滚动
> if (orientation == StaggeredGridLayoutManager.VERTICAL)
> {
> childCount = childCount - childCount % spanCount;
> // 如果是最后一行，则不需要绘制底部
> if (pos >= childCount)
> return true;
> } else
> // StaggeredGridLayoutManager 且横向滚动
> {
> // 如果是最后一行，则不需要绘制底部
> if ((pos + 1) % spanCount == 0)
> {
> return true;
> }
> }
> }
> return false;
> }
> 
> @Override
> public void getItemOffsets(Rect outRect, int itemPosition,
> RecyclerView parent)
> {
> int spanCount = getSpanCount(parent);
> int childCount = parent.getAdapter().getItemCount();
> if (isLastRaw(parent, itemPosition, spanCount, childCount))// 如果是最后一行，则不需要绘制底部
> {
> outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
> } else if (isLastColum(parent, itemPosition, spanCount, childCount))// 如果是最后一列，则不需要绘制右边
> {
> outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
> } else
> {
> outRect.set(0, 0, mDivider.getIntrinsicWidth(),
> mDivider.getIntrinsicHeight());
> }
> }
> }
> </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li><li style="box-sizing: border-box; padding: 0px 5px;">64</li><li style="box-sizing: border-box; padding: 0px 5px;">65</li><li style="box-sizing: border-box; padding: 0px 5px;">66</li><li style="box-sizing: border-box; padding: 0px 5px;">67</li><li style="box-sizing: border-box; padding: 0px 5px;">68</li><li style="box-sizing: border-box; padding: 0px 5px;">69</li><li style="box-sizing: border-box; padding: 0px 5px;">70</li><li style="box-sizing: border-box; padding: 0px 5px;">71</li><li style="box-sizing: border-box; padding: 0px 5px;">72</li><li style="box-sizing: border-box; padding: 0px 5px;">73</li><li style="box-sizing: border-box; padding: 0px 5px;">74</li><li style="box-sizing: border-box; padding: 0px 5px;">75</li><li style="box-sizing: border-box; padding: 0px 5px;">76</li><li style="box-sizing: border-box; padding: 0px 5px;">77</li><li style="box-sizing: border-box; padding: 0px 5px;">78</li><li style="box-sizing: border-box; padding: 0px 5px;">79</li><li style="box-sizing: border-box; padding: 0px 5px;">80</li><li style="box-sizing: border-box; padding: 0px 5px;">81</li><li style="box-sizing: border-box; padding: 0px 5px;">82</li><li style="box-sizing: border-box; padding: 0px 5px;">83</li><li style="box-sizing: border-box; padding: 0px 5px;">84</li><li style="box-sizing: border-box; padding: 0px 5px;">85</li><li style="box-sizing: border-box; padding: 0px 5px;">86</li><li style="box-sizing: border-box; padding: 0px 5px;">87</li><li style="box-sizing: border-box; padding: 0px 5px;">88</li><li style="box-sizing: border-box; padding: 0px 5px;">89</li><li style="box-sizing: border-box; padding: 0px 5px;">90</li><li style="box-sizing: border-box; padding: 0px 5px;">91</li><li style="box-sizing: border-box; padding: 0px 5px;">92</li><li style="box-sizing: border-box; padding: 0px 5px;">93</li><li style="box-sizing: border-box; padding: 0px 5px;">94</li><li style="box-sizing: border-box; padding: 0px 5px;">95</li><li style="box-sizing: border-box; padding: 0px 5px;">96</li><li style="box-sizing: border-box; padding: 0px 5px;">97</li><li style="box-sizing: border-box; padding: 0px 5px;">98</li><li style="box-sizing: border-box; padding: 0px 5px;">99</li><li style="box-sizing: border-box; padding: 0px 5px;">100</li><li style="box-sizing: border-box; padding: 0px 5px;">101</li><li style="box-sizing: border-box; padding: 0px 5px;">102</li><li style="box-sizing: border-box; padding: 0px 5px;">103</li><li style="box-sizing: border-box; padding: 0px 5px;">104</li><li style="box-sizing: border-box; padding: 0px 5px;">105</li><li style="box-sizing: border-box; padding: 0px 5px;">106</li><li style="box-sizing: border-box; padding: 0px 5px;">107</li><li style="box-sizing: border-box; padding: 0px 5px;">108</li><li style="box-sizing: border-box; padding: 0px 5px;">109</li><li style="box-sizing: border-box; padding: 0px 5px;">110</li><li style="box-sizing: border-box; padding: 0px 5px;">111</li><li style="box-sizing: border-box; padding: 0px 5px;">112</li><li style="box-sizing: border-box; padding: 0px 5px;">113</li><li style="box-sizing: border-box; padding: 0px 5px;">114</li><li style="box-sizing: border-box; padding: 0px 5px;">115</li><li style="box-sizing: border-box; padding: 0px 5px;">116</li><li style="box-sizing: border-box; padding: 0px 5px;">117</li><li style="box-sizing: border-box; padding: 0px 5px;">118</li><li style="box-sizing: border-box; padding: 0px 5px;">119</li><li style="box-sizing: border-box; padding: 0px 5px;">120</li><li style="box-sizing: border-box; padding: 0px 5px;">121</li><li style="box-sizing: border-box; padding: 0px 5px;">122</li><li style="box-sizing: border-box; padding: 0px 5px;">123</li><li style="box-sizing: border-box; padding: 0px 5px;">124</li><li style="box-sizing: border-box; padding: 0px 5px;">125</li><li style="box-sizing: border-box; padding: 0px 5px;">126</li><li style="box-sizing: border-box; padding: 0px 5px;">127</li><li style="box-sizing: border-box; padding: 0px 5px;">128</li><li style="box-sizing: border-box; padding: 0px 5px;">129</li><li style="box-sizing: border-box; padding: 0px 5px;">130</li><li style="box-sizing: border-box; padding: 0px 5px;">131</li><li style="box-sizing: border-box; padding: 0px 5px;">132</li><li style="box-sizing: border-box; padding: 0px 5px;">133</li><li style="box-sizing: border-box; padding: 0px 5px;">134</li><li style="box-sizing: border-box; padding: 0px 5px;">135</li><li style="box-sizing: border-box; padding: 0px 5px;">136</li><li style="box-sizing: border-box; padding: 0px 5px;">137</li><li style="box-sizing: border-box; padding: 0px 5px;">138</li><li style="box-sizing: border-box; padding: 0px 5px;">139</li><li style="box-sizing: border-box; padding: 0px 5px;">140</li><li style="box-sizing: border-box; padding: 0px 5px;">141</li><li style="box-sizing: border-box; padding: 0px 5px;">142</li><li style="box-sizing: border-box; padding: 0px 5px;">143</li><li style="box-sizing: border-box; padding: 0px 5px;">144</li><li style="box-sizing: border-box; padding: 0px 5px;">145</li><li style="box-sizing: border-box; padding: 0px 5px;">146</li><li style="box-sizing: border-box; padding: 0px 5px;">147</li><li style="box-sizing: border-box; padding: 0px 5px;">148</li><li style="box-sizing: border-box; padding: 0px 5px;">149</li><li style="box-sizing: border-box; padding: 0px 5px;">150</li><li style="box-sizing: border-box; padding: 0px 5px;">151</li><li style="box-sizing: border-box; padding: 0px 5px;">152</li><li style="box-sizing: border-box; padding: 0px 5px;">153</li><li style="box-sizing: border-box; padding: 0px 5px;">154</li><li style="box-sizing: border-box; padding: 0px 5px;">155</li><li style="box-sizing: border-box; padding: 0px 5px;">156</li><li style="box-sizing: border-box; padding: 0px 5px;">157</li><li style="box-sizing: border-box; padding: 0px 5px;">158</li><li style="box-sizing: border-box; padding: 0px 5px;">159</li><li style="box-sizing: border-box; padding: 0px 5px;">160</li><li style="box-sizing: border-box; padding: 0px 5px;">161</li><li style="box-sizing: border-box; padding: 0px 5px;">162</li><li style="box-sizing: border-box; padding: 0px 5px;">163</li><li style="box-sizing: border-box; padding: 0px 5px;">164</li><li style="box-sizing: border-box; padding: 0px 5px;">165</li><li style="box-sizing: border-box; padding: 0px 5px;">166</li><li style="box-sizing: border-box; padding: 0px 5px;">167</li><li style="box-sizing: border-box; padding: 0px 5px;">168</li><li style="box-sizing: border-box; padding: 0px 5px;">169</li><li style="box-sizing: border-box; padding: 0px 5px;">170</li><li style="box-sizing: border-box; padding: 0px 5px;">171</li><li style="box-sizing: border-box; padding: 0px 5px;">172</li><li style="box-sizing: border-box; padding: 0px 5px;">173</li><li style="box-sizing: border-box; padding: 0px 5px;">174</li><li style="box-sizing: border-box; padding: 0px 5px;">175</li><li style="box-sizing: border-box; padding: 0px 5px;">176</li><li style="box-sizing: border-box; padding: 0px 5px;">177</li><li style="box-sizing: border-box; padding: 0px 5px;">178</li></ul>
> 
> 主要在`getItemOffsets`方法中，去判断如果是最后一行，则不需要绘制底部；如果是最后一列，则不需要绘制右边，整个判断也考虑到了`StaggeredGridLayoutManager`的横向和纵向，所以稍稍有些复杂。最重要还是去理解，如何绘制什么的不重要。一般如果仅仅是希望有空隙，还是去设置item的margin方便。
> 
> 最后的效果是：
> 
> ![20150415150026088][]
> 
> ok，看到这，你可能还觉得RecyclerView不够强大？
> 
> 但是如果我们有这么个需求，纵屏的时候显示为ListView，横屏的时候显示两列的GridView，我们RecyclerView可以轻松搞定，而如果使用ListView去实现还是需要点功夫的~~~
> 
> 当然了，这只是皮毛，下面让你心服口服。
> 
> * StaggeredGridLayoutManager
> 
> 瀑布流式的布局，其实他可以实现`GridLayoutManager`一样的功能，仅仅按照下列代码：
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">// mRecyclerView.setLayoutManager(new GridLayoutManager(this,4));
> mRecyclerView.setLayoutManager(new StaggeredGridLayoutManager(4, StaggeredGridLayoutManager.VERTICAL));</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>
> 
> 这两种写法显示的效果是一致的，但是注意StaggeredGridLayoutManager构造的第二个参数传一个orientation，如果传入的是`StaggeredGridLayoutManager.VERTICAL`代表有多少列；那么传入的如果是`StaggeredGridLayoutManager.HORIZONTAL`就代表有多少行，比如本例如果改为：
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">mRecyclerView.setLayoutManager(new StaggeredGridLayoutManager(4,
> StaggeredGridLayoutManager.HORIZONTAL));</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>
> 
> 那么效果为：
> 
> ![20150415150125431][]
> 
> 可以看到，固定为4行，变成了左右滑动。有一点需要注意，如果是横向的时候，item的宽度需要注意去设置，毕竟横向的宽度没有约束了，应为控件可以横向滚动了。  
> 如果你需要一样横向滚动的GridView，那么恭喜你。
> 
> ok，接下来准备看大招，如果让你去实现个瀑布流，最起码不是那么随意就可以实现的吧？但是，如果使用RecyclerView，分分钟的事。  
> 那么如何实现？其实你什么都不用做，只要使用`StaggeredGridLayoutManager`我们就已经实现了，只是上面的item布局我们使用了固定的高度，下面我们仅仅在适配器的`onBindViewHolder`方法中为我们的item设置个随机的高度（代码就不贴了，最后会给出源码下载地址），看看效果图：
> 
> ![20150415193645985][]
> 
> 是不是棒棒哒，通过RecyclerView去实现ListView、GridView、瀑布流的效果基本上没有什么区别，而且可以仅仅通过设置不同的LayoutManager即可实现。
> 
> 还有更nice的地方，就在于item增加、删除的动画也是可配置的。接下来看一下ItemAnimator。
> 
> ### ItemAnimator ###
> 
> ItemAnimator也是一个抽象类，好在系统为我们提供了一种默认的实现类，期待系统多  
> 添加些默认的实现。
> 
> 借助默认的实现，当Item添加和移除的时候，添加动画效果很简单:
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">// 设置item动画
> mRecyclerView.setItemAnimator(new DefaultItemAnimator());</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li></ul>
> 
> 系统为我们提供了一个默认的实现，我们为我们的瀑布流添加以上一行代码，效果为：
> 
> ![20150415194114149][]
> 
> 如果是GridLayoutManager呢？动画效果为：
> 
> ![20150415150130083][]
> 
> 注意，这里更新数据集不是用`adapter.notifyDataSetChanged()`而是  
> `notifyItemInserted(position)`与`notifyItemRemoved(position)`  
> 否则没有动画效果。  
> 上述为adapter中添加了两个方法：
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">public void addData(int position) {
> mDatas.add(position, "Insert One");
> notifyItemInserted(position);
> }
> 
> public void removeData(int position) {
> mDatas.remove(position);
> notifyItemRemoved(position);
> }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul>
> 
> Activity中点击MenuItem触发：
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"> @Override
> public boolean onCreateOptionsMenu(Menu menu)
> {
> getMenuInflater().inflate(R.menu.main, menu);
> return super.onCreateOptionsMenu(menu);
> }
> 
> @Override
> public boolean onOptionsItemSelected(MenuItem item)
> {
> switch (item.getItemId())
> {
> case R.id.id_action_add:
> mAdapter.addData(1);
> break;
> case R.id.id_action_delete:
> mAdapter.removeData(1);
> break;
> }
> return true;
> }</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li></ul>
> 
> 好了，到这我对这个控件已经不是一般的喜欢了~~~
> 
> 当然了只提供了一种动画，那么我们肯定可以去自定义各种nice的动画效果。  
> 高兴的是，github上已经有很多类似的项目了，这里我们直接引用下：[RecyclerViewItemAnimators][]，大家自己下载查看。  
> 提供了`SlideInOutLeftItemAnimator`,`SlideInOutRightItemAnimator`,  
> `SlideInOutTopItemAnimator`,`SlideInOutBottomItemAnimator`等动画效果。
> 
> ### Click and LongClick ###
> 
> 不过一个挺郁闷的地方就是，系统没有提供ClickListener和LongClickListener。  
> 不过我们也可以自己去添加，只是会多了些代码而已。  
> 实现的方式比较多，你可以通过mRecyclerView.addOnItemTouchListener去监听然后去判断手势，  
> 当然你也可以通过adapter中自己去提供回调，这里我们选择后者，前者的方式，大家有兴趣自己去实现。
> 
> 那么代码也比较简单：
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">class HomeAdapter extends RecyclerView.Adapter<HomeAdapter.MyViewHolder>
> {
> 
> //...
> public interface OnItemClickLitener
> {
> void onItemClick(View view, int position);
> void onItemLongClick(View view , int position);
> }
> 
> private OnItemClickLitener mOnItemClickLitener;
> 
> public void setOnItemClickLitener(OnItemClickLitener mOnItemClickLitener)
> {
> this.mOnItemClickLitener = mOnItemClickLitener;
> }
> 
> @Override
> public void onBindViewHolder(final MyViewHolder holder, final int position)
> {
> holder.tv.setText(mDatas.get(position));
> 
> // 如果设置了回调，则设置点击事件
> if (mOnItemClickLitener != null)
> {
> holder.itemView.setOnClickListener(new OnClickListener()
> {
> @Override
> public void onClick(View v)
> {
> int pos = holder.getLayoutPosition();
> mOnItemClickLitener.onItemClick(holder.itemView, pos);
> }
> });
> 
> holder.itemView.setOnLongClickListener(new OnLongClickListener()
> {
> @Override
> public boolean onLongClick(View v)
> {
> int pos = holder.getLayoutPosition();
> mOnItemClickLitener.onItemLongClick(holder.itemView, pos);
> return false;
> }
> });
> }
> }
> //...
> }
> </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li></ul>
> 
> adapter中自己定义了个接口，然后在onBindViewHolder中去为holder.itemView去设置相应  
> 的监听最后回调我们设置的监听。
> 
> 最后别忘了给item添加一个drawable:
> 
> <code class="language-xml hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><?xml version="1.0" encoding="utf-8"?>
> <selector xmlns:android="http://schemas.android.com/apk/res/android" >
> <item android:state_pressed="true" android:drawable="@color/color_item_press"></item>
> <item android:drawable="@color/color_item_normal"></item>
> </selector>
> </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li></ul>
> 
> Activity中去设置监听：
> 
> <code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">
> mAdapter.setOnItemClickLitener(new OnItemClickLitener()
> {
> 
> @Override
> public void onItemClick(View view, int position)
> {
> Toast.makeText(HomeActivity.this, position + " click",
> Toast.LENGTH_SHORT).show();
> }
> 
> @Override
> public void onItemLongClick(View view, int position)
> {
> Toast.makeText(HomeActivity.this, position + " long click",
> Toast.LENGTH_SHORT).show();
> mAdapter.removeData(position);
> }
> });
> </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li></ul>
> 
> 测试效果：
> 
> ![20150415194800546][]
> 
> ok，到此我们基本介绍了RecylerView常见用法，包含了：
> 
> * 系统提供了几种LayoutManager的使用；
> * 如何通过自定义ItemDecoration去设置分割线，或者一些你想作为分隔的drawable，注意这里  
> 巧妙的使用了系统的listDivider属性，你可以尝试添加使用divider和dividerHeight属性。
> * 如何使用ItemAnimator为RecylerView去添加Item移除、添加的动画效果。
> * 介绍了如何添加ItemClickListener与ItemLongClickListener。
> 
> 可以看到RecyclerView可以实现：
> 
> * ListView的功能
> * GridView的功能
> * 横向ListView的功能，参考[Android 自定义RecyclerView 实现真正的Gallery效果][DividerItemDecoration]
> * 横向ScrollView的功能
> * 瀑布流效果
> * 便于添加Item增加和移除动画
> 
> 整个体验下来，感觉这种插拔式的设计太棒了，如果系统再能提供一些常用的分隔符，多添加些动画效果就更好了。
> 
> 通过简单改变下LayoutManager，就可以产生不同的效果，那么我们可以根据手机屏幕的宽度去动态设置LayoutManager，屏幕宽度一般的，显示为ListView；宽度稍大的显示两列的GridView或者瀑布流（或者横纵屏幕切换时变化，有点意思~）；显示的列数和宽度成正比。甚至某些特殊屏幕，让其横向滑动~~再选择一个nice的动画效果，相信这种插件式的编码体验一定会让你迅速爱上RecyclerView。
> 
> ### 参考资料 ###
> 
> [Android 自定义RecyclerView 实现真正的Gallery效果][DividerItemDecoration]
> 
> [A First Glance at Android’s RecyclerView][A First Glance at Android_s RecyclerView]
> 
> [https://github.com/gabrielemariotti/RecyclerViewItemAnimators][RecyclerViewItemAnimators]
> 
> [DividerItemDecoration][DividerItemDecoration 1]
> 
> 
>

[http_blog.csdn.net_lmj623565791_article_details_45059587]: http://blog.csdn.net/lmj623565791/article/details/45059587
[Link 1]: http://blog.csdn.net/lmj623565791/
[20150415145840351]: /images/20220731/300d2a9c730543abb6b23f2206e1a86d.png
[DividerItemDecoration]: http://blog.csdn.net/lmj623565791/article/details/38173061
[20150415145931083]: /images/20220731/176f128e87c34c6aa13fce46a008bb80.png
[20150415151013289]: /images/20220731/d29a183e4ba843088b262798045c5176.png
[20150415150026088]: /images/20220731/600ee0870b8b4c28adfbc7159d69495e.png
[20150415150125431]: /images/20220731/a86f904ea8994f13b66b763f76e10dc2.png
[20150415193645985]: /images/20220731/07e5f6dab4a945138af519aff5ab254f.png
[20150415194114149]: /images/20220731/f5c29c33879244ca946e20577ba689ea.png
[20150415150130083]: /images/20220731/0a691729e4d74fd4bcfc1d5270e5d56c.png
[RecyclerViewItemAnimators]: https://github.com/gabrielemariotti/RecyclerViewItemAnimators
[20150415194800546]: /images/20220731/e015d5e34f0f4f10b307532db79c4e08.png
[A First Glance at Android_s RecyclerView]: https://www.grokkingandroid.com/first-glance-androids-recyclerview/
[DividerItemDecoration 1]: https://gist.github.com/alexfu/0f464fc3742f134ccd1e