安卓Fragment的用法

一、程序图

二、布局文件

（1）main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical" >    <FrameLayout        android:id="@+id/contain"        android:layout_width="fill_parent"        android:layout_height="20px"        android:layout_weight="9" >    </FrameLayout>    <LinearLayout        android:layout_width="fill_parent"        android:layout_height="20px"        android:layout_weight="1"        android:orientation="horizontal" >        <Button            android:id="@+id/fg_one_btn"            android:layout_width="20px"            android:layout_height="fill_parent"            android:layout_margin="3px"            android:layout_weight="1"            android:text="First" />        <Button            android:id="@+id/fg_two_btn"            android:layout_width="20px"            android:layout_height="fill_parent"            android:layout_weight="1"            android:layout_margin="3px"            android:text="Second" />        <Button            android:id="@+id/fg_three_btn"            android:layout_width="20px"            android:layout_height="fill_parent"            android:layout_margin="3px"            android:layout_weight="1"             android:text="Three"/>    </LinearLayout></LinearLayout>

  (2) first.xml

<?xml version="1.0" encoding="UTF-8"?><LinearLayout     xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_height="fill_parent"    android:layout_width="fill_parent"    android:background="#123"    android:gravity="center"    android:orientation="vertical">        <TextView         android:layout_height="wrap_content"        android:layout_width="wrap_content"        android:text="FirstFragment"/>        <Button         android:id="@+id/hello"        android:layout_height="wrap_content"        android:layout_width="wrap_content"        android:text="点击"/>    </LinearLayout>

 (3) second.xml

<?xml version="1.0" encoding="UTF-8"?><LinearLayout     xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_height="fill_parent"    android:layout_width="fill_parent"    android:background="#000"    android:gravity="center">        <TextView         android:layout_height="wrap_content"        android:layout_width="wrap_content"        android:text="SecondFragment"        android:textColor="#fff"/>        </LinearLayout>

(4) three.xml

<?xml version="1.0" encoding="UTF-8"?><LinearLayout     xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_height="fill_parent"    android:layout_width="fill_parent"    android:background="#bd0708"    android:gravity="center">        <TextView         android:layout_height="wrap_content"        android:layout_width="wrap_content"        android:text="ThreeFragment"/>        </LinearLayout>

三、程序

（1）FragmentActivity.java

import com.liu.cn.fragment.FirstFragment;import com.liu.cn.fragment.SecondFragment;import com.liu.cn.fragment.ThirdFragment;import android.app.Activity;import android.app.Fragment;import android.content.Context;import android.graphics.Color;import android.os.Bundle;import android.view.LayoutInflater;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class FragmentActivity extends Activity implements OnClickListener{   Button one,two,three;   LayoutInflater inflater;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        inflater=(LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);        init();    }    public View getLayoutView(int layoutId){    View v=inflater.inflate(layoutId, null);    return v;    }    private void init(){    one=(Button) this.findViewById(R.id.fg_one_btn);    two=(Button) this.findViewById(R.id.fg_two_btn);    three=(Button) this.findViewById(R.id.fg_three_btn);    one.setOnClickListener(this);    two.setOnClickListener(this);    three.setOnClickListener(this);    normalColor();    //初始化第一个fragment    FirstFragment ff=new FirstFragment();    switchView(ff, one);    }    //正常颜色    private void normalColor(){    one.setBackgroundColor(Color.BLUE);    two.setBackgroundColor(Color.BLUE);    three.setBackgroundColor(Color.BLUE);    }    //fragment之间的转换，并且改变对应的按钮颜色    private void switchView(Fragment fg,View v){    v.setBackgroundColor(Color.GRAY);    getFragmentManager().beginTransaction().    replace(R.id.contain, fg).commit();    }public void onClick(View v) {normalColor();int id=v.getId();switch (id) {case R.id.fg_one_btn:FirstFragment ff=new FirstFragment();switchView(ff, v);break;case R.id.fg_two_btn:SecondFragment sf=new SecondFragment();switchView(sf, v);break;case R.id.fg_three_btn:ThirdFragment tf=new ThirdFragment();switchView(tf, v);break;default:break;}}}

(2)   BaseFragment .java

import com.liu.cn.R.layout;import android.R.integer;import android.app.Fragment;import android.os.Bundle;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;//定义一个抽象基类BaseFragment,当3个fragment之间有公用的方法时，可把方法写在这里，其他fragment继承//Basefragment，方法可以之间调用，好处就在这儿，用的久了就体现出来了public abstract class BaseFragment extends Fragment{private FragmentActivity activity;public  View LayoutView;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);//强转，调用fragmentActivity中的getLayoutView方法；activity=(FragmentActivity) getActivity();//下面俩行不能颠倒，否则空指针错误，原因是找不到布局文件LayoutView=activity.getLayoutView(getLayoutId());createChild(savedInstanceState);}@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {return LayoutView;}public abstract void createChild( Bundle savedInstanceState);public abstract int getLayoutId();}

(3)  FirstFragment.java

import com.liu.cn.BaseFragment;import com.liu.cn.R;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.Toast;//在找布局文件中的组件时，可按下面的按钮示例初始化，并做其他的事情，其他的fragment初始化都一样//在这里就不多啰嗦了,剩下的俩个fragment中你们可以练习下public class FirstFragment extends BaseFragment{@Overridepublic void createChild(Bundle savedInstanceState) {Button firstBtn=(Button) LayoutView.findViewById(R.id.hello);firstBtn.setOnClickListener(new OnClickListener() {public void onClick(View v) {Toast.makeText(getActivity(),"点击了第一个Framgment中的按钮", 0).show();}});}@Overridepublic int getLayoutId() {// TODO Auto-generated method stubreturn R.layout.first;}}

(4) Secondfragment.java

import android.os.Bundle;import com.liu.cn.BaseFragment;import com.liu.cn.R;public class SecondFragment extends BaseFragment{@Overridepublic void createChild(Bundle savedInstanceState) {}@Overridepublic int getLayoutId() {// TODO Auto-generated method stubreturn R.layout.second;}}

(5) ThirdFragment,java

import android.os.Bundle;import com.liu.cn.BaseFragment;import com.liu.cn.R;public class ThirdFragment extends BaseFragment {@Overridepublic void createChild(Bundle savedInstanceState) {}@Overridepublic int getLayoutId() {// TODO Auto-generated method stubreturn R.layout.three;}}