android进程间服务通信

两个进程间的Service需要进行通信，则需要把对象序列化后进行互相发送。
Android提供了一个 AIDL (Android接口定义语言)工具来处理序列化和通信。这种情况下Service需要以aidl文件的方式提供服务接口，AIDL工具将生成一个相应的java接口，并且在生成的服务接口中包含一个功能调用的stub服务桩类。Service的实现类需要去继承这个 stub服务桩类。Service的onBind方法会返回实现类的对象，之后你就可以使用它了.现在来实现一个HelloWorld级的服务以及在Activity中使用这个服务。步骤如下:

1.编写aidl文件,在这个文件中提供了服务所提供的方法的接口,文件的扩展名为aidl,在我们的示例中命名为IDataTimeService.aidl文件的内容为如下所示:

package com.services.demo2;

// Declare the interface.
interface IDataTimeService {
    String getCurrentDataTime();
}

package com.services.demo2;

// Declare the interface.
interface IDataTimeService {
	String getCurrentDataTime();
}

 

2.编写服务的实现类,在这个示例中为DataTimeService.java,内容如下:

public class DataTimeService extends Service{
    public static final String BROADCAST_ACTION = "com.services.demo2.DataTimeServiceEvent";
    /**
      使用上面定义的字符串常量创建一个Intent的实例,如果服务在运行的过程中发生的事件都可以通过Service的
      sendBroadcast(broadcast)方法来发送一个广播消息通知Activity,然后有Activity注册的接收者进行处理;
      */
    private Intent broadcast = new Intent(BROADCAST_ACTION);
    sendBroadcast(broadcast);
    private final IDataTimeService.Stub binder = new IDataTimeService.Stub() {
        public String getCurrentDataTime() {
            return (getCurrentDataTimeImpl());
        }
    };
    synchronized private String getCurrentDataTimeImpl() {
        Date date=new Date();
        return (date.toLocaleString());
    }
    @Override
    public IBinder onBind(Intent intent) {
        return (binder);
    }
}

public class DataTimeService extends Service{
	public static final String BROADCAST_ACTION = "com.services.demo2.DataTimeServiceEvent";
	/**
	  使用上面定义的字符串常量创建一个Intent的实例,如果服务在运行的过程中发生的事件都可以通过Service的
	  sendBroadcast(broadcast)方法来发送一个广播消息通知Activity,然后有Activity注册的接收者进行处理;
	  */
	private Intent broadcast = new Intent(BROADCAST_ACTION);
	sendBroadcast(broadcast);
	private final IDataTimeService.Stub binder = new IDataTimeService.Stub() {
		public String getCurrentDataTime() {
			return (getCurrentDataTimeImpl());
		}
	};
	synchronized private String getCurrentDataTimeImpl() {
		Date date=new Date();
		return (date.toLocaleString());
	}
	@Override
	public IBinder onBind(Intent intent) {
		return (binder);
	}
}

 

3.现在编写一个Activity,来消费这个服务:

 

public class ServicesDemo2 extends Activity {
    private IDataTimeService service = null;
    private Intent serviceIntent = null;
    private WebView browser;
    private ServiceConnection svcConn = new ServiceConnection() {
        public void onServiceConnected(ComponentName className, IBinder binder) {
            service = IDataTimeService.Stub.asInterface(binder);

            browser.postDelayed(new Runnable() {
                public void run() {
                    updateForecast();
                }
            }, 1000);
        }

        public void onServiceDisconnected(ComponentName className) {
            service = null;
        }
    };

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        browser = (WebView) findViewById(R.id.webkit);
        serviceIntent = new Intent(this, DataTimeServiceImpl.class);
        //绑定一个服务
        bindService(serviceIntent, svcConn, BIND_AUTO_CREATE);
    }

    @Override
    public void onResume() {
        super.onResume();
        /**
          注册广播消息的接收者,在android中服务与Activity的通信依靠广播发送消息,然后由Activity注册的接收者
          接收到消息,进行相应的处理这里使用DataTimeServiceImpl.BROADCAST_ACTION来过滤,表明它只接收
          DataTimeService中的调用sendBroadcast(broadcast)发送的广播消息;
          */
        registerReceiver(receiver, new IntentFilter(
                DataTimeServiceImpl.BROADCAST_ACTION));
    }

    @Override
    public void onPause() {
        super.onPause();
        unregisterReceiver(receiver);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        unbindService(svcConn);
    }

    private void updateForecast() {
        try {
            String page = service.getForecastPage();
            if (page != null) {
                browser.loadDataWithBaseURL(null, page, "text/html", "UTF-8",
                        null);
                browser.postDelayed(new Runnable() {
                    public void run() {
                        updateForecast();
                    }
                }, 1000);
            }
        } catch (final Throwable t) {
            svcConn.onServiceDisconnected(null);
        }
    }

    //接收者实例
    private BroadcastReceiver receiver = new BroadcastReceiver() {
        public void onReceive(Context context, Intent intent) {
            runOnUiThread(new Runnable() {
                public void run() {
                    updateForecast();
                }
            });
        }
    };
}