RecycleView的分割线基础

落日映苍穹つ 2022-05-19 05:42 160阅读 0赞

## RecycleView很多人可能用不习惯，觉得太麻烦了，但是实际上用起来的时候功能非常强大。话不多说开始吧。 ##

## ItemDecoration这个是RecycleView分割线 ##

//自定义一个类继承RecyclerView.ItemDecoration
    public class CustomDividerItem extends RecyclerView.ItemDecoration

> 接下来需要实现的是getItemOffsets这个主要的方法

@Override
        public void getItemOffsets(Rect outRect, View view, RecyclerView parent,RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        //拿到当前RecycleView的布局管理器
        final RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
        //由于每个item都会调用一次这个方法,所以我们需要拿到每个item
        final int current = parent.getChildLayoutPosition(view);
        //拿到总的item数目
        final int lastPosition =  state.getItemCount() - 1;
        //接下来要做的就是在这个方法里面分割

> 分割每个 Item

//在上面的方法中我们有一个参数outRect 我们需要仔细的理解这个参数，这个参数是每个item的边框
    outRect.set(decoration,decoration,decoration,decoration);
    //这个方法有四个参数经过我的测试，可以理解为margin分别是左上右下的margin

## 源码 ##

package com.example.administrator.testactivity.custom;
    
    import android.content.Context;
    import android.graphics.Rect;
    import android.support.v7.widget.GridLayoutManager;
    import android.support.v7.widget.LinearLayoutManager;
    import android.support.v7.widget.RecyclerView;
    import android.util.Log;
    import android.view.View;
    
    
    public class CustomDividerItem extends RecyclerView.ItemDecoration{ 
        private int dividerHeight;
        private static final int HORIZONTAL = LinearLayoutManager.HORIZONTAL;//处于水平状态
        private static final int VERTICAL = LinearLayoutManager.VERTICAL;// 处于垂直状态
        private int orientation; //方向
        private final int decoration;// 边距大小
    
    
        public CustomDividerItem(int orientation, int decoration) {
            this.orientation = orientation;
            this.decoration = decoration;
        }
    
        /** * 这个方法每个item都会调用一次 * @param outRect * @param view * @param parent * @param state */
        @Override
        public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
            super.getItemOffsets(outRect, view, parent, state);
            final RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
            //整个recycleview最后一个item的position, getItemCout数目比实际的item个数多一个
            final int lastPosition = state.getItemCount() - 1;
            //获取当前需要布局的item
            final int current = parent.getChildLayoutPosition(view);
            Log.e("0000", "0000---->" + current);
            Log.e("0000", "0000state.getItemCount()---->" + state.getItemCount());
            Log.e("0000", "0000getTargetScrollPosition---->" + state.getTargetScrollPosition());
            Log.e("0000", "0000state---->" + state.toString());
            if(current == -1) {
                return;
            }
            if (layoutManager instanceof LinearLayoutManager && !(layoutManager instanceof GridLayoutManager)){
                //垂直
                if (orientation == LinearLayoutManager.VERTICAL){
                        outRect.set(decoration,decoration,decoration,decoration);
    
                }else{
       //水平
                    if (current == lastPosition){
                        outRect.set(0,0,0,0);
                    }else{
                        outRect.set(0,0,decoration,0);
                    }
                }
            }
    
        }
    }

## 效果 ##

![这里写图片描述][70]

[70]: /images/20220519/23e53e8fff904a7eb7187b5bda1e315b.png