Android开发-在Activity中，左右平均布局fragment的实现

柔情只为你懂 2023-10-16 19:57 11阅读 0赞

#### 1. 简介： ####

Android Fragment已经被应用程序大量使用。本篇介绍“在Activity中，左右平均布局fragment”的一种实现方式。

#### 2. 效果图： ####

![8ceb590a50fe499cb3ec625bff36f5df.png][]

#### 3. 源代码： ####

**3.1 activity中的布局文件：**

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal" >
    
        <fragment class="com.excelsecu.myfragloadertest.LeftFragment"
            android:id="@+id/left_fragment" android:layout_weight="1"
            android:layout_width="0px" android:layout_height="match_parent"
            />
    
        <fragment class="com.excelsecu.myfragloadertest.RightFragment"
            android:id="@+id/right_fragment" android:layout_weight="1"
            android:layout_width="0px" android:layout_height="match_parent"
            />
    
    </LinearLayout>

说明：

（1）顶层布局文件使用LinearLayout，并且是左右排列：

android:orientation="horizontal"；

（2）直接在xml中定义两个Fragment的布局，需要设置

android:layout\_weight=“1”，平均分割；

**3.2 列表item的布局：**

<?xml version="1.0" encoding="utf-8"?>
    
    
    <TextView xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@android:id/text1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceListItemSmall"
        android:gravity="center_vertical"
        android:paddingStart="?android:attr/listPreferredItemPaddingStart"
        android:paddingEnd="?android:attr/listPreferredItemPaddingEnd"
        android:minHeight="?android:attr/listPreferredItemHeightSmall" />

说明：

item只有一个TextView文本。

**3.3LeftFragment代码：**

package com.excelsecu.myfragloadertest;
    
    import android.app.Activity;
    import android.app.AlertDialog;
    import android.app.FragmentTransaction;
    import android.app.ListFragment;
    import android.os.Bundle;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.ArrayAdapter;
    import android.widget.ListView;
    
    public class LeftFragment extends ListFragment {
        boolean mDualPane;
        int mCurCheckPosition = 0;
    
        private static String[] array = {
                "02-01,", "02-02", "02-03", "02-04", "02-05", "02-06", "02-07",
                "02-08","02-09", "02-10", "02-11", "02-12", "02-13", "02-14",
                "02-15", "02-16","02-17,", "02-18", "02-19", "02-20", "02-21",
                "02-22", "02-23", "02-24","02-25", "02-26", "02-27", "02-28"};
    
        @Override
        public void onCreate(Bundle savedInstanceState) {
            // TODO Auto-generated method stub
            super.onCreate(savedInstanceState);
            System.out.println("Fragment-->onCreate");
        }
    
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            // TODO Auto-generated method stub
            System.out.println("Fragment-->onCreateView");
            return super.onCreateView(inflater, container, savedInstanceState);
        }
    
        @Override
        public void onPause() {
            // TODO Auto-generated method stub
            super.onPause();
            System.out.println("Fragment-->onPause");
        }
    
        @Override
        public void onStop() {
            // TODO Auto-generated method stub
            super.onStop();
    
            System.out.println("Fragment-->onStop");
        }
    
        @Override
        public void onAttach(Activity activity) {
            // TODO Auto-generated method stub
            super.onAttach(activity);
            System.out.println("Fragment-->onAttach");
        }
    
        @Override
        public void onStart() {
            // TODO Auto-generated method stub
            super.onStart();
            System.out.println("Fragment-->onStart");
        }
    
        @Override
        public void onResume() {
            // TODO Auto-generated method stub
            super.onResume();
            System.out.println("Fragment-->onResume");
        }
    
        @Override
        public void onDestroy() {
            // TODO Auto-generated method stub
            super.onDestroy();
            System.out.println("Fragment-->onDestroy");
        }
    
        @Override
        public void onActivityCreated(Bundle savedInstanceState) {
            // TODO Auto-generated method stub
            super.onActivityCreated(savedInstanceState);
            System.out.println("Fragment-->onActivityCreted");
            setListAdapter(new ArrayAdapter<String>(getActivity(),
                    android.R.layout.simple_list_item_1, array));
    
            View detailsFrame = getActivity().findViewById(R.id.details);
    
            mDualPane = detailsFrame != null
                    && detailsFrame.getVisibility() == View.VISIBLE;
    
            if (savedInstanceState != null) {
                mCurCheckPosition = savedInstanceState.getInt("curChoice", 0); // 从保存的状态中取出数据
            }
    
            if (mDualPane) {
                getListView().setChoiceMode(ListView.CHOICE_MODE_SINGLE);
    
                showDetails(mCurCheckPosition);
            }
        }
    
        @Override
        public void onSaveInstanceState(Bundle outState) {
            // TODO Auto-generated method stub
            super.onSaveInstanceState(outState);
    
            outState.putInt("curChoice", mCurCheckPosition);// 保存当前的下标
        }
    
        @Override
        public void onListItemClick(ListView l, View v, int position, long id) {
            // TODO Auto-generated method stub
            super.onListItemClick(l, v, position, id);
            showDetails(position);
        }
    
        void showDetails(int index) {
            mCurCheckPosition = index;
            if (mDualPane) {
                getListView().setItemChecked(index, true);
                DetailsFragment details = (DetailsFragment) getFragmentManager()
                        .findFragmentById(R.id.details);
                if (details == null || details.getShownIndex() != index) {
                    details = DetailsFragment.newInstance(mCurCheckPosition);
    
                    // 得到一个fragment 事务（类似sqlite的操作）
                    FragmentTransaction ft = getFragmentManager()
                            .beginTransaction();
                    ft.replace(R.id.details, details);// 将得到的fragment
                    // 替换当前的viewGroup内容，add则不替换会依次累加
                    ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);// 设置动画效果
                    ft.commit();// 提交
                }
            } else {
                new AlertDialog.Builder(getActivity()).setTitle(
                        android.R.string.dialog_alert_title).setMessage(
                        MyFragmentDemoActivity.array[index]).setPositiveButton(android.R.string.ok,
                        null).show();
            }
        }
    }

说明：

（1）继承自ListFragment；

（2）array定义了数据；

（3）setListAdapter:适配器，用于将数据和ui进行绑定；

（4）onListItemClick：点击iteml时会调用这个方法；

（5）onActivityCreated：Fragment生命周期管理相关的一个方法，当Actiivty被创建后，这个方法会被调用。

**3.4RightFragment代码：**

同“LeftFragment”，只是数据array不一样。

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[8ceb590a50fe499cb3ec625bff36f5df.png]: https://img-blog.csdnimg.cn/8ceb590a50fe499cb3ec625bff36f5df.png