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。