摘要

本文介绍了Android中一个Activity中有多个Fragment的情况下，Fragment之间如何通过Activity进行互操作。

源代码

源代码地址为：http://download.csdn.net/detail/logicteamleader/8931199
源代码使用ADT编写，ADT版本为2014，Android版本为android-22。

技术要点

1.在Activity中的多个Fragment之间要互操作，一定要通过此Activity，不能直接通信；
2.在Activity中添加Fragment可以使用id或者Tag，建议使用Tag，这样无论该Fragment有没有界面，都可以被Activity使用findFragmentByTag方法找到；
3.在Fragment中定义回调接口，让Activity实现此回调接口，这样就能让Activity响应Fragment中的消息；
4.不同的Fragment之间要互操作，还是通过Activity实现回调接口来实现，例如FragmentA中回调MainActivity中的OnBtnAClicked方法，而OnBtnAClicked方法中又调用了FragmentB的changeB方法，达到了两个Fragment之间的互操作。

FragmentA的源代码

package com.apkkids.fragmentinactivityexample;import android.app.Activity;import android.os.Bundle;import android.support.annotation.Nullable;import android.support.v4.app.Fragment;import android.view.LayoutInflater;import android.view.View;import android.view.View.OnClickListener;import android.view.ViewGroup;import android.widget.Button;import android.widget.TextView;public class FragmentA extends Fragment {    private static int iChange = 1;    private TextView tvA;    //回调接口，此接口必须被MainActivity实现，并通过此接口回调来进行Fragment和Activity之间的互操作    public OnFragmentABtnClickedListener mCallback = null;    public interface OnFragmentABtnClickedListener{        public void OnBtnAClicked();    }    @Override    public void onAttach(Activity activity) {        super.onAttach(activity);        try{            mCallback = (OnFragmentABtnClickedListener)activity;        }catch(ClassCastException e){            throw new ClassCastException(activity.toString() + " must implement OnFragmentABtnClickedListener");        }    }    @Override    @Nullable    public View onCreateView(LayoutInflater inflater,            @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {        View v = inflater.inflate(R.layout.fragmenta_layout, container, false);        tvA = (TextView) v.findViewById(R.id.tvA);        Button btnA = (Button) v.findViewById(R.id.buttonA);        //点击此按钮，通过回调接口，使得FragmentB中的textView改变        btnA.setOnClickListener( new OnClickListener() {            @Override            public void onClick(View v) {                if(mCallback != null){                    mCallback.OnBtnAClicked();                }            }        });        return v;    }    public void changeA() {        if (tvA != null) {            tvA.setText("TextView in FragmentA changed by FragmentB :"                    + iChange++);        }    }}

FragmentB的源代码

package com.apkkids.fragmentinactivityexample;import android.app.Activity;import android.os.Bundle;import android.support.annotation.Nullable;import android.support.v4.app.Fragment;import android.view.LayoutInflater;import android.view.View;import android.view.View.OnClickListener;import android.view.ViewGroup;import android.widget.Button;import android.widget.TextView;public class FragmentB extends Fragment {    private static int iChange = 1;    private TextView tvB;    // 回调接口，此接口必须被MainActivity实现，并通过此接口回调来进行Fragment和Activity之间的互操作    public OnFragmentBBtnClickedListener mCallback = null;    public interface OnFragmentBBtnClickedListener {        public void OnBtnBClicked();    }    @Override    public void onAttach(Activity activity) {        super.onAttach(activity);        try {            mCallback = (OnFragmentBBtnClickedListener) activity;        } catch (ClassCastException e) {            throw new ClassCastException(activity.toString()                    + " must implement OnFragmentBBtnClickedListener");        }    }    @Override    @Nullable    public View onCreateView(LayoutInflater inflater,            @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {        View v = inflater.inflate(R.layout.fragmentb_layout, container, false);        tvB = (TextView) v.findViewById(R.id.tvB);        Button btnB = (Button) v.findViewById(R.id.buttonB);        btnB.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                if (mCallback != null) {                    mCallback.OnBtnBClicked();                }            }        });        return v;    }    /**     * 改变Text的值     */    public void changeB() {        if (tvB != null) {            tvB.setText("TextView in FragmentB changed by FragmentA :"                    + iChange++);        }    }}

MainActivity的源代码

package com.apkkids.fragmentinactivityexample;import android.os.Bundle;import android.support.v4.app.FragmentActivity;import android.support.v4.app.FragmentManager;import android.support.v4.app.FragmentTransaction;import android.view.Menu;import android.view.MenuItem;/** * @author wxb * Description:Activity中多个Fragment之间互操作的示例，主要使用回调接口方法实现。 *             注意：Fragment之间是不能直接通信的，一定要通过它们附着的Activity进行 * * 2015-7-24 * 下午10:02:45 */public class MainActivity extends FragmentActivity  implements FragmentA.OnFragmentABtnClickedListener,FragmentB.OnFragmentBBtnClickedListener {    private static final String FRAGMENT_A_TAG = "com.apkkids.fragmentA";    private static final String FRAGMENT_B_TAG = "com.apkkids.fragmentB";    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        FragmentA fragmentA = new FragmentA();        FragmentB fragmentB = new FragmentB();        FragmentManager fragmentManager  = getSupportFragmentManager();        FragmentTransaction  transaction = fragmentManager.beginTransaction();        //使用Tag方式添加Fragment，此外还可以用id方式添加        transaction.add(R.id.containerA, fragmentA, FRAGMENT_A_TAG);        transaction.add(R.id.containerB, fragmentB, FRAGMENT_B_TAG);        transaction.commit();    }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        getMenuInflater().inflate(R.menu.main, menu);        return true;    }    @Override    public boolean onOptionsItemSelected(MenuItem item) {        int id = item.getItemId();        if (id == R.id.action_settings) {            return true;        }        return super.onOptionsItemSelected(item);    }    /* (non-Javadoc)     * @see com.apkkids.fragmentinactivityexample.FragmentA.OnAClickedListener#OnAClicked()     * FragmentA中定义的回调接口的方法，通过此方法修改FragmentB中的UI     */    @Override    public void OnBtnAClicked() {        //得到FragmentB的实例         FragmentManager fragmentManager  = getSupportFragmentManager();         FragmentB fragmentB = (FragmentB) fragmentManager.findFragmentByTag(FRAGMENT_B_TAG);         if(fragmentB != null)             fragmentB.changeB();    }    @Override    public void OnBtnBClicked() {        //得到FragmentA的实例         FragmentManager fragmentManager  = getSupportFragmentManager();         FragmentA fragmentA = (FragmentA) fragmentManager.findFragmentByTag(FRAGMENT_A_TAG);         if(fragmentA != null)             fragmentA.changeA();    }}

程序执行界面

小结

其他界面代码请从源代码包下载，都是不需要积分的。