Service和Activity通讯的3种常用方式示例

一般的Android业务开发中，Service的使用十分常见。稍微复杂点的业务逻辑，都需要Serivice在执行某些耗时操作后通知Activity。总结常见的三种方法。

分别是：（1）binder持有Activity的Handler对象，或者持有一个Activity的callbackInterface.

（2）AIDL实现，完美支持IPC。

（3）startService+broadcastReceiver实现。

另外还有几种不推荐的方式，都有很高的局限性。比如Service执行后的结果持久化，通过startActivity在目标Activity中的OnNewIntent()处理（需要Activity是单例的)。

（1）Binder持有Activity的Handler，这里推荐Handler弱引用Activity实现。

关键代码如下：

public class WeakReferenceHandlerActivity extends Activity {private MyHandler mHandler;public static int FLAG = 10;public ProgressBar progressBar;private Button bindButton;private Button nextButton;private UseHandlerService.MyBinder myBinder;  @Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.handler_layout);progressBar = (ProgressBar)this.findViewById(R.id.progress);bindButton = (Button)this.findViewById(R.id.bind);nextButton = (Button)this.findViewById(R.id.next);mHandler = new MyHandler(this);bindButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {bindService();Log.d("","startDownLoad() --> click");}});nextButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {startActivity(new Intent(WeakReferenceHandlerActivity.this,AndroidAidlActivity.class));}});}      private ServiceConnection connection = new ServiceConnection() {            @Override          public void onServiceDisconnected(ComponentName name) {                  }            @Override          public void onServiceConnected(ComponentName name, IBinder service) {         Log.d("","startDownLoad() --> onbind");            myBinder = (UseHandlerService.MyBinder) service;              myBinder.setCallBackHandler(mHandler);            myBinder.startDownLoad();                    }      };      @Overrideprotected void onResume() {    super.onResume();}        @Overrideprotected void onPause() {    unBindService();super.onPause();}        public void bindService(){    Intent bindIntent = new Intent(this, UseHandlerService.class);          bindService(bindIntent, connection, BIND_AUTO_CREATE);      }        public void unBindService(){    unbindService(connection);    }    @Overrideprotected void onDestroy() {// Remove all Runnable and Message.mHandler.removeCallbacksAndMessages(null);super.onDestroy();}public MyHandler getHandler(){return mHandler;}public class MyHandler extends Handler {// WeakReference to the outer class's instance.private WeakReference mOuter;public MyHandler(WeakReferenceHandlerActivity activity) {mOuter = new WeakReference(activity);}@Overridepublic void handleMessage(Message msg) {WeakReferenceHandlerActivity outer = mOuter.get();if (outer != null) {// Do something with outer as your wish.if(!outer.isFinishing()){int progress = msg.what;progressBar.setProgress(progress);}}}}}

public class UseHandlerService extends Service{/** * 进度条的最大值 */public static final int MAX_PROGRESS = 100; /** * 进度条的进度值 */private int progress = 0;/** * 更新进度的回调接口 */private MyHandler myHandler;private MyBinder mBinder = new MyBinder();  private String TAG = "UseHandlerService";/** * 注册回调接口的方法，供外部调用 * @param onProgressListener */public void setHandler(MyHandler handler) {myHandler = handler;}/** * 增加get()方法，供Activity调用 * @return 下载进度 */public int getProgress() {return progress;}@Override      public void onCreate() {          super.onCreate();          Log.d(TAG, "onCreate() executed");      }        @Override      public int onStartCommand(Intent intent, int flags, int startId) {          Log.d(TAG, "onStartCommand() executed");          return super.onStartCommand(intent, flags, startId);      }        @Override      public void onDestroy() {          super.onDestroy();          Log.d(TAG, "onDestroy() executed");      }  /** * 返回一个Binder对象 */@Overridepublic IBinder onBind(Intent intent) {return mBinder;}public class MyBinder extends Binder{/** * 获取当前Service的实例 * @return */public UseHandlerService getService(){return UseHandlerService.this;}public void setCallBackHandler(MyHandler handler){myHandler = handler;}public void startDownLoad(){Log.d("","startDownLoad() inBinder-->");new Thread(new Runnable() {public void run() {while(progress < MAX_PROGRESS){progress += 5;Log.d("","startDownLoad() run-->");//进度发生变化通知调用方if(myHandler != null){myHandler.sendEmptyMessage(progress);}try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();}}}}).start();}}}

弱引用的实现，是出于防止Service不销毁，一直导致目标Activity也不能会回收的考虑。

（2）AIDL实现，同样还是进度条的UI更新。

public class AndroidAidlActivity extends Activity {    /** Called when the activity is first created. */public static final int MAX_PROGRESS = 100; /** * 进度条的进度值 */private int progress = 0;public ProgressBar progressBar;private Button bindButton;private MyAIDLService mService;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.handler_layout);                progressBar = (ProgressBar)this.findViewById(R.id.progress);        bindButton = (Button)this.findViewById(R.id.bind);bindButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {bindService();Log.d("","startDownLoad() --> click");}});this.findViewById(R.id.next).setVisibility(View.GONE);    }        private ICallBack.Stub mCallback = new ICallBack.Stub() {              @Override         public void showResult(final int result) {             Log.d("", "showresult -->" + result);             progressBar.setProgress(result);         }    };        private ServiceConnection connection = new ServiceConnection() {          @Override          public void onServiceDisconnected(ComponentName name) {          mService = null;        }          @Override          public void onServiceConnected(ComponentName name, IBinder service) {         Log.d("","startDownLoad() --> onbind");        mService = MyAIDLService.Stub.asInterface(service);        try {            mService.registerCallback(mCallback);            mService.startDownload();        } catch (RemoteException e) {            Log.e("", "", e);        }                    }      };      @Overrideprotected void onResume() {super.onResume();}        @Overrideprotected void onPause() {    unBindService();super.onPause();}        public void bindService(){    Intent bindIntent = new Intent(this, AidlService.class);          bindService(bindIntent, connection, BIND_AUTO_CREATE);      }        public void unBindService(){    unbindService(connection);    }    @Overrideprotected void onDestroy() {// Remove all Runnable and Message.super.onDestroy();}}public class AidlService extends Service {private RemoteCallbackList mCallbacks = new RemoteCallbackList();MyAIDLService.Stub mBinder = new Stub() {@Overridepublic void registerCallback(ICallBack cb) throws RemoteException {if(cb != null) {                    mCallbacks.register(cb);}}@Overridepublic void unregisterCallback(ICallBack cb) throws RemoteException {if(cb != null) {                    mCallbacks.unregister(cb);}}@Overridepublic void startDownload() throws RemoteException {Log.d("","startDownLoad() inBinder-->");new Thread(new Runnable() {public void run() {while(progress < MAX_PROGRESS){progress += 5;Log.d("","startDownLoad() run-->");//进度发生变化通知调用方if(mHandler != null){//TODOmHandler.sendEmptyMessage(progress);}try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();}}}}).start();}};/** * 进度条的最大值 */public static final int MAX_PROGRESS = 100; /** * 进度条的进度值 */private int progress = 0;/** * 更新进度的回调接口 */private String TAG = "UseHandlerService";/** * 增加get()方法，供Activity调用 * @return 下载进度 */public int getProgress() {return progress;}@Override      public void onCreate() {          super.onCreate();          //mHandler.sendEmptyMessageDelayed(0, 1000);        Log.d(TAG, "onCreate() executed");      }  private void callBack(Message msg) {int N = mCallbacks.beginBroadcast();try {    for (int i = 0; i < N; i++) {    Log.d("","mCallbacks -->progress"+msg.what);        mCallbacks.getBroadcastItem(i).showResult(msg.what);    }} catch (RemoteException e) {      Log.e(TAG, "", e);}mCallbacks.finishBroadcast();}private Handler mHandler = new Handler() {       @Override      public void handleMessage(Message msg) {           callBack(msg);           super.handleMessage(msg);      }};    @Override      public int onStartCommand(Intent intent, int flags, int startId) {          Log.d(TAG, "onStartCommand() executed");          return super.onStartCommand(intent, flags, startId);      }        @Override      public void onDestroy() {          super.onDestroy();          Log.d(TAG, "onDestroy() executed");      }  /** * 返回一个Binder对象 */@Overridepublic IBinder onBind(Intent intent) {return mBinder;}}还有两个AIDL文件package com.banking.hello;interface ICallBack {    void showResult(int result);} package com.banking.hello;import com.banking.hello.ICallBack;interface MyAIDLService {void registerCallback(ICallBack cb);    void unregisterCallback(ICallBack cb);    void startDownload();}

这种方式，无论Service是否是remote，都可以实现高效率通讯。

（3）第三种通过Receiver非常简单，就不上代码了。
sendBroadCast,然后在Activity中注册一个相对应的内部receiver接受就可以了.

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