Android Fragment和FragmentActivity区别和用法

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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_Second) {                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：

<pre name="code" class="java">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_Second) {                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

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