选项卡样式的fragment

Fragment其实就是一个小的Activity，他的生命周期和Activity差不多。Fragment概念的提出就是因为平板编程的需要，Fragment使得UI设计得以模块化，平板等大屏设备的UI设计得到了很好的技术支持。然而Fragment概念的提出是因为大屏UI设计的需求，但是使用并不局限于平板设计。下面这坨代码（的确是坨。。）实现的是一个类似微信的选项卡切换界面的功能，全局只有一个Activity，真正改变的只是Fragment。

Activity:

package com.example.myfragment;

import android.os.Bundle;
import android.app.Activity;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.TextView;

public class MainActivity extends Activity implements OnClickListener {
private TextView tv1;
private TextView tv2;
private TextView tv3;
private TextView tv4;

private FragmentManager fm;
private Fragment1 fragment1;
private Fragment2 fragment2;
private Fragment3 fragment3;
private Fragment4 fragment4;

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

tv1 = (TextView) findViewById(R.id.text1);
tv2 = (TextView) findViewById(R.id.text2);
tv3 = (TextView) findViewById(R.id.text3);
tv4 = (TextView) findViewById(R.id.text4);

tv1.setOnClickListener(this);
tv2.setOnClickListener(this);
tv3.setOnClickListener(this);
tv4.setOnClickListener(this);

fm = getFragmentManager();
FragmentTransaction ft = fm.beginTransaction();

fragment1 = new Fragment1();
fragment2 = new Fragment2();
fragment3 = new Fragment3();
fragment4 = new Fragment4();

ft.replace(R.id.content, fragment1);
ft.commit();
}

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
FragmentTransaction ft = fm.beginTransaction();
switch (v.getId()) {
case R.id.text1:
ft.replace(R.id.content, fragment1);
break;
case R.id.text2:
ft.replace(R.id.content, fragment2);
break;
case R.id.text3:
ft.replace(R.id.content, fragment3);
break;
case R.id.text4:
ft.replace(R.id.content, fragment4);
break;
}
ft.commit();
}
}


activity xml:
<LinearLayout 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:orientation="vertical" >

<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >

<TextView
android:id="@+id/text1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:gravity="center"
android:text="Text1" />

<TextView
android:id="@+id/text2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:gravity="center"
android:text="Text2" />

<TextView
android:id="@+id/text3"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:gravity="center"
android:text="Text3" />

<TextView
android:id="@+id/text4"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:gravity="center"
android:text="Text4" />
</LinearLayout>

<RelativeLayout
android:id="@+id/content"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
</RelativeLayout>

</LinearLayout>

fragment1:

package com.example.myfragment;

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

public class Fragment1 extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment1, null);
return view;
}
}

f1 xml:

<?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" >

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Fragment1"
android:textSize="20dp" >
</TextView>

</LinearLayout>

fragment2到fragment4的定义方式和fragment1类似，这里就不贴出来了。