Service使用方式

 

使用Service的场合：

1.一个或多个Activity需要向同一应用中的Service发出执行某一操作的命令。

PS：不需要绑定

 

 

 

2.某个Activity需要同一应用中的Service为其单独服务，当此Activity消毁时，也将为其服务的Service一并消毁。

PS：需要绑定

 

 

 

3.多个Activity绑定到同一个Service，仅当所有Activity取消了绑定，Service才消毁。

PS：只有第一个Activity绑定时才调用onBind()方法，第二个、第三个....第N个直接取得第一个Activity绑定时onBind()方法返回的IBinder对象

 

 

 

4.即使退出当前应用时，仍希望Service继续运行（如：上传或下载任务）；或者此Service为其他应用提供服务。

PS：需要跨进程通信（IPC）

4.1当远程服务不需要支持多线程时，使用Messager.

 

Server端应用代码

 

public class RemoteServiceProxy extends Service {
    public static final int GET_RESULT = 1;
    private final Messenger mMessenger = new Messenger(new Handler() {
        private int status = 0;
        @Override
        public void handleMessage(Message msg) {
            if (msg.what == GET_RESULT) {
                try {
                    msg.replyTo.send(Message.obtain(null, GET_RESULT, status++, 0));
                } catch (RemoteException e) {
                    e.printStackTrace();
                }
            } else {
                super.handleMessage(msg);
            }
        }
    });
    
    @Override
    public IBinder onBind(Intent intent) {
        return mMessenger.getBinder();
    }
}

 

 

 

<service android:name=".module.photo.RemoteServiceProxy"
                 android:process=":remote" />

 

 

Client端应用代码

 

//开启一个服务
bindService(new Intent(this, RemoteServiceProxy.class), mConnection, BIND_AUTO_CREATE);

private Messenger mService;
private ServiceConnection mConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            mService = new Messenger(service);
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
        }
};

 

private Messenger mMessenger = new Messenger(new Handler() {
        @Override
        public void handleMessage(Message msg) {
            if (msg.what == RemoteServiceProxy.GET_RESULT) {
                Log.i("M", "From Remote Service "+msg.arg1);
            } else {
                super.handleMessage(msg);
            }
        }
});

Message message = Message.obtain(null, RemoteServiceProxy.GET_RESULT);
message.replyTo = mMessenger;
try {
        mService.send(message);
} catch (RemoteException e) {
        e.printStackTrace();
}

 

 

 

4.2当远程服务需要同时响应多个Client的请求，使用AIDL.

注意：一般我们应用中是不需要使用AIDL的，这里仅仅是为了学习和深入理解Android的IPC机制。

 

Server端应用代码

 

在Server端应用新建IRemoteService.aidl和IRemoteCallback.aidl文件，编辑内容如下

 

 

package com.example.aidl;

interface IRemoteCallback {
    void executeCallback(String msg);
}

 

 

package com.example.aidl;

import com.example.aidl.IRemoteCallback;

interface IRemoteService {
    //注册回调
    void register(IRemoteCallback callback);
    //取消注册回调
    void unregister(IRemoteCallback callback);
    //执行回调
    void execute();
    //获取状态
    int getStatus(String flag);
}

 

创建Service类为客户端提供服务

 

 

package com.example.server.service;

import com.example.aidl.IRemoteCallback;
import com.example.aidl.IRemoteService;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.os.RemoteCallbackList;
import android.os.RemoteException;
import android.util.Log;

public class RemoteService extends Service {

	@Override
	public IBinder onBind(Intent intent) {
		return iBinder;
	}
	
	private final RemoteCallbackList<IRemoteCallback> remoteCallbackList = new RemoteCallbackList<IRemoteCallback>(); 
	
	private IRemoteService.Stub iBinder = new IRemoteService.Stub() {
		@Override
		public void register(IRemoteCallback cb) throws RemoteException {
			if (cb != null) remoteCallbackList.register(cb);
		}

		@Override
		public void unregister(IRemoteCallback cb) throws RemoteException {
			if (cb != null) remoteCallbackList.unregister(cb);
		}

		@Override
		public void execute() throws RemoteException {
			int size = remoteCallbackList.beginBroadcast();
			while (size > 0) {
				size--;
				remoteCallbackList.getBroadcastItem(size).executeCallback("Hello, Client.");
			}
			remoteCallbackList.finishBroadcast();
			Log.i("RS", "RemoteService.execute() has done.");
		}

		int status;
		@Override
		public int getStatus(String flag) throws RemoteException {
			Log.i("RS", "RemoteService.getStatus(flag) flag is "+flag);
			if ("reset".equals(flag)) status = 0;
			return status++;
		}
	};
}

 

在AndroidManifast.xml中配置Service，必需设置Action过滤

 

 

<service android:name=".server.service.RemoteService" android:process=":remote">
            <intent-filter>
            	<action android:name="test.remote.service"/>
            </intent-filter>
</service>

 

 

 

Client端应用代码

 

将Server端创建的IRemoteService.aidl和IRemoteCallback.aidl文件copy到Client端应用中

 

在Client端获取Server端的RemoteService对象的引用

 

 

package com.example;

import com.example.aidl.IRemoteCallback;
import com.example.aidl.IRemoteService;

import android.app.Activity;
import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.os.RemoteException;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Toast;

public class ClientActivity extends Activity {
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.client_activity);
		
		/*
		   绑定远程服务，与其他进程Service通信。
		   注意：Client需要通过Action与RemoteService绑定，因为Client端是没有RemoteService.class的
		 */
		this.bindService(new Intent("test.remote.service"), sConnection, BIND_AUTO_CREATE);
		
		this.findViewById(R.id.execute_callback).setOnClickListener(mOnClickListener);
		this.findViewById(R.id.get_status).setOnClickListener(mOnClickListener);
	}

	private OnClickListener mOnClickListener = new OnClickListener() {
		@Override
		public void onClick(View button) {
			try {
				if (button.getId() == R.id.execute_callback) remoteService.execute();
				else {
					int remoteStatus = remoteService.getStatus("set");
					Toast.makeText(getApplicationContext(), "Status: "+remoteStatus+" is from RemoteService", Toast.LENGTH_LONG).show();
				}
			} catch (RemoteException e) {
				e.printStackTrace();
			}
		}
	};
	
	private IRemoteService remoteService;//远程服务
	private ServiceConnection sConnection = new ServiceConnection() {
		@Override
		public void onServiceConnected(ComponentName name, IBinder service) {
			remoteService = IRemoteService.Stub.asInterface(service);
			//注册回调
			try {
				remoteService.register(remoteCallback);
			} catch (RemoteException e) {
				e.printStackTrace();
			}
		}

		@Override
		public void onServiceDisconnected(ComponentName name) {
			//意外断开连接时回调
			remoteService = null;
		}
	};
	
	private IRemoteCallback.Stub remoteCallback = new IRemoteCallback.Stub() {
		@Override
		public void executeCallback(String msg) throws RemoteException {
			Toast.makeText(getApplicationContext(), "ClientActivity: "+msg, Toast.LENGTH_LONG).show();
		}
	};
}

 

 

 

 

评论

3 楼 大智若愚 2013-03-28  

学习一下

2 楼 wangguangji 2011-11-29  

不好意思 是我不会弄！是可以运行的！

1 楼 wangguangji 2011-11-29  

怎么你的这些代码 都编辑不能通过呢！不好意思我是初学android