【学习】Service与Activity之间通信的几种方式

原文地址

通过broadcast(广播)的形式

当我们的进度发生变化的时候我们发送一条广播，然后在Activity的注册广播接收器，接收到广播之后更新ProgressBar,代码如下

package com.example.communication;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;

public class MainActivity extends Activity {
private ProgressBar mProgressBar;
private Intent mIntent;
private MsgReceiver msgReceiver;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

//动态注册广播接收器
msgReceiver = new MsgReceiver();
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction("com.example.communication.RECEIVER");
registerReceiver(msgReceiver, intentFilter);

mProgressBar = (ProgressBar) findViewById(R.id.progressBar1);
Button mButton = (Button) findViewById(R.id.button1);
mButton.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
//启动服务
mIntent = new Intent("com.example.communication.MSG_ACTION");
startService(mIntent);
}
});

}

@Override
protected void onDestroy() {
//停止服务
stopService(mIntent);
//注销广播
unregisterReceiver(msgReceiver);
super.onDestroy();
}

/**
* 广播接收器
* @author len
*
*/
public class MsgReceiver extends BroadcastReceiver{

@Override
public void onReceive(Context context, Intent intent) {
//拿到进度，更新UI
int progress = intent.getIntExtra("progress", 0);
mProgressBar.setProgress(progress);
}
}
}

package com.example.communication;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;

public class MsgService 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;

private Intent intent = new Intent("com.example.communication.RECEIVER");

/**
* 模拟下载任务，每秒钟更新一次
*/
public void startDownLoad(){
new Thread(new Runnable() {

@Override
public void run() {
while(progress < MAX_PROGRESS){
progress += 5;

//发送Action为com.example.communication.RECEIVER的广播
intent.putExtra("progress", progress);
sendBroadcast(intent);

try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}

}
}
}).start();
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
startDownLoad();
return super.onStartCommand(intent, flags, startId);
}

@Override
public IBinder onBind(Intent intent) {
return null;
}

}

总结:

Activity调用bindService (Intent service, ServiceConnection conn, int flags)方法，得到Service对象的一个引用，这样Activity可以直接调用到Service中的方法，如果要主动通知Activity，我们可以利用回调方法

Service向Activity发送消息，可以使用广播，当然Activity要注册相应的接收器。比如Service要向多个Activity发送同样的消息的话，用这种方法就更好