Android使用Fragment实现标签页

Fragment的概念是从Android3.0开始引入的，直译为碎片、片段，目的是为不同屏幕大小的设备(手机、平板等)创建灵活动态的UI。诚如其名，你可以把Fragment当作是Activity的模块化组件，它拥有自己的生命周期和UI，接受自身的处理事件，可以在Activity运行中被动态的添加、移除、替换。

Fragment必须被写成可重用的模块，你可以将多个Fragment组合到一个Activity中创建一个多模块界面，也可以在多个Activity中包含同一个Fragment的不同实例，这对于你的界面在不同屏幕尺寸下都能给用户完美的体验至关重要。

Fragment不能独立存在，它必须嵌入到Activity中，因此 Fragment的生命周期也依赖于Activity的生命周期，当其依赖的Activity的某个生命周期方法被调用时，该Activity下包含的所有Fragment的相应生命周期方法也将被调用，如onPause()，onStop()，onDestroy()等。

代码如下：

一、layout

1、主窗口

</FrameLayout>

</LinearLayout>

2、第一个Fragement

<?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="vertical" >

</LinearLayout>
3、第二个Fragement

</LinearLayout>
4、第三个Fragement

</LinearLayout>

二、源代码

1、fragmentActity1

package com.example.fragmentdemo;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class fragmentActity1 extends Fragment {

   @Override
   public View onCreateView(LayoutInflater inflater, ViewGroup container,
   Bundle savedInstanceState){
   return inflater.inflate(R.layout.fragment1, container, false);
   }

}

2、fragmentActity2

package com.example.fragmentdemo;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class fragmentActity2 extends Fragment {

   @Override
   public View onCreateView(LayoutInflater inflater, ViewGroup container,
   Bundle savedInstanceState){
   return inflater.inflate(R.layout.fragment2, container, false);
   }

}

3、fragmentActity3

package com.example.fragmentdemo;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class fragmentActity3 extends Fragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState){
return inflater.inflate(R.layout.fragment3, container, false);
}

}

4、主窗口

package com.example.fragmentdemo;

import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends FragmentActivity implements OnClickListener {

   private Button button1 ,button2,button3;
   private FragmentTransaction fragmentTransaction;
   private fragmentActity1 frame1;
   private fragmentActity2 frame2;
   private fragmentActity3 frame3;

   private int currentTabIndex = 0;
   private final int TAB_INDEX1 = 0;
   private final int TAB_INDEX2 = 1;
   private final int TAB_INDEX3 = 2;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

initViews();
}

   private void initViews() {

       button1 = (Button) findViewById(R.id.button1);
button2 = (Button) findViewById(R.id.button2);
button3 = (Button) findViewById(R.id.button3);

button1.setOnClickListener(this);
button2.setOnClickListener(this);
button3.setOnClickListener(this);

       setTabSelected(TAB_INDEX1);

   }

   private void hideFragment(FragmentTransaction fragment) {
       if (frame1 != null)
           fragment.hide(frame1);
       if (frame2 != null)
           fragment.hide(frame2);
       if (frame3 != null)
           fragment.hide(frame3);
   }

   private void setTabSelected(int i) {
       fragmentTransaction = getFragmentManager().beginTransaction();

       hideFragment(fragmentTransaction);
       clearSelectedState();

       switch (i) {
       case TAB_INDEX1:
           button1.setSelected(true);

           if (frame1 == null) {
               frame1 = new fragmentActity1();
               fragmentTransaction.add(R.id.framelayout, frame1);
           } else {
               fragmentTransaction.show(frame1);
           }

           break;
       case TAB_INDEX2:
           button1.setSelected(true);

           if (frame2 == null) {
               frame2 = new fragmentActity2();
               fragmentTransaction.add(R.id.framelayout, frame2);
           } else {
               fragmentTransaction.show(frame2);
           }

           break;
       case TAB_INDEX3:
           button1.setSelected(true);

           if (frame3 == null) {
               frame3 = new fragmentActity3();
               fragmentTransaction.add(R.id.framelayout, frame3);
           } else {
               fragmentTransaction.show(frame3);
           }
           break;
       }

       fragmentTransaction.commit();

   }

   private void clearSelectedState() {
       button1.setSelected(false);
       button2.setSelected(false);
       button3.setSelected(false);
   }

   @Override
   public void onClick(View v) {
       hideFragment(fragmentTransaction);

       switch (v.getId()) {
       case R.id.button1:
           setTabSelected(TAB_INDEX1);
           break;
       case R.id.button2:
           setTabSelected(TAB_INDEX2);
           break;
       case R.id.button3:
           setTabSelected(TAB_INDEX3);
           break;
       }


   }

}

运行效果如下：

Android使用Fragment实现标签页