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:

Java代码


package


com.services.demo2;

// Declare the interface.

interface


IDataTimeService {

String getCurrentDataTime();

}

Java代码

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:

Java代码


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);

}

}

Java代码

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:

Java代码


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();

}

});

}

};

}