Android Fragment和FragmentActivity区别和用法

Android Fragment是Android4.0以上才有的；而FragmentActivity是为了兼容4.0以下版本的Fragment使用的。

所以如果你想兼容4.0以下Android版本使用Fragment的话，框架Activity需要继承FragmentActivity，FragmentActivity这个类是在android.support.v4.app.FragmentActivity里的。

下面介绍2种用法：

1、继承Activity的。

（这个只针对4.0以上的Android平台使用Fragment）。

框架Activity：

package com.tandong.fragment;

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

/**
* 不兼容4.0以下模式Fragment
*
* @author tandong
*
*/

public class Mt_Activity extends Activity implements OnClickListener {
private Button btn_first, btn_second;
private Fragment Fragment_first, Fragment_Second;
private FragmentTransaction fragmentTransaction;
private FragmentManager fragmentManager;

@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment);
initView();

Fragment_Second = new Fragment_Second();
fragmentManager = this.getFragmentManager();
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.main_fragment_layout, Fragment_Second,"second_Fragment");
fragmentTransaction.commit();
}

private void initView() {
btn_first = (Button) this.findViewById(R.id.btn_first);
btn_second = (Button) this.findViewById(R.id.btn_second);
btn_first.setOnClickListener(this);
btn_second.setOnClickListener(this);
}

@Override
public void onClick(View arg0) {
switch (arg0.getId()) {
case R.id.btn_first:
// 加载不同的Fragment
if (null == Fragment_first) {
Fragment_first = new Fragment_first();
}
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.main_fragment_layout, Fragment_first, "fist_Fragment");
fragmentTransaction.commit();
break;
case R.id.btn_second:
if (null == Fragment_first) {
Fragment_Second = new Fragment_Second();
}
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.main_fragment_layout, Fragment_Second, "second_Fragment");
fragmentTransaction.commit();
break;
default:
break;
}

}

}

Fragment代码：

package com.tandong.fragment;

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

public class Fragment_Second extends Fragment {
private View rootView;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
if(container==null)
return null;
rootView = inflater.inflate(R.layout.fragment_two, container,false);

return rootView;
}
}

2.继承FragmentActivity的（向下兼容4.0以下版本使用Fragment，导入的是android.support.v4包里的内容）

框架Activity：

package com.tandong.fragment;

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

/**
* 兼容4.0以下模式Fragment
*
* @author tandong
*
*/

public class Mt_Activity extends FragmentActivity implements OnClickListener {
private Button btn_first, btn_second;
private Fragment Fragment_first, Fragment_Second;
private FragmentTransaction fragmentTransaction;
private FragmentManager fragmentManager;

@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment);
initView();

Fragment_first = new Fragment_first();
fragmentManager = this.getSupportFragmentManager();
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.main_fragment_layout, Fragment_first,"first_Fragment");
fragmentTransaction.commit();
}

private void initView() {
btn_first = (Button) this.findViewById(R.id.btn_first);
btn_second = (Button) this.findViewById(R.id.btn_second);
btn_first.setOnClickListener(this);
btn_second.setOnClickListener(this);
}

@Override
public void onClick(View arg0) {
switch (arg0.getId()) {
case R.id.btn_first:
// 加载不同的Fragment
if (null == Fragment_first) {
Fragment_first = new Fragment_first();
}
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.main_fragment_layout, Fragment_first, "fist_Fragment");
fragmentTransaction.commit();
break;
case R.id.btn_second:
if (null == Fragment_first) {
Fragment_Second = new Fragment_Second();
}
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.main_fragment_layout, Fragment_Second, "second_Fragment");
fragmentTransaction.commit();
break;
default:
break;
}

}

}

Fragment代码：

package com.tandong.fragment;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class Fragment_first extends Fragment {
private View rootView;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
if(container==null)
return null;
rootView = inflater.inflate(R.layout.fragment_first, container,false);

return rootView;
}
}

最后再说一句布局：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<LinearLayout
android:id="@+id/top_bar_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:orientation="horizontal" >

<Button
android:id="@+id/btn_one"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:background="@drawable/top_bar_bg"
android:text="按钮一" />

<Button
android:id="@+id/btn_two"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:background="@drawable/top_bar_bg"
android:text="按钮二" />

</LinearLayout>

<LinearLayout
android:id="@+id/fragment_replace_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@id/top_bar_layout"
android:background="#ff0000" >
</LinearLayout>

</RelativeLayout>

布局类似这种布局即可，并不是一定非要FrameLayout