Android下实现程序关闭后，监听取消

原文地址::http://www.cnblogs.com/tt_mc/archive/2010/03/03/1677474.html





在先前的文章中，接收短信的监听器会一直活在后台，哪怕程序被关闭，监听器会一直存在并在收到消息时激活主程序。在一般的设计中，都不会这么做，因为这是浪费资源且得不到良好用户体验的。因此需要在自己的程序并闭后，将监听器取消。前文链接（点击进入）

一、建立一个后台服务，该服务用于接收消息并将消息广播给BroadcastReceiver。由于服务可以被终止，终止时不再转发消息，后台的BroadcastReceiver也因此不再生效，会自动被GC回收。程序的目标也达到了

package com.demo;

import android.app.Service;

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.content.IntentFilter;

import android.os.Bundle;

import android.os.IBinder;

import android.telephony.gsm.SmsMessage;

public class ListenService
extends Service {

public static final String SvrId =
"RARNU.SERVICE.DEMO";

public static final String strACT =
"android.provider.Telephony.SMS_RECEIVED";

private SMSMsgReceiver recv;

@Override

public void onStart(Intent intent,
int startId) {

super.onStart(intent, startId);

}

@Override

public void onCreate() {

IntentFilter filter = new IntentFilter(strACT);

recv = new SMSMsgReceiver();

registerReceiver(recv, filter);

super.onCreate();

}

@Override

public IBinder onBind(Intent intent) {

return null;

}

@Override

public void onDestroy() {

unregisterReceiver(recv);

super.onDestroy();

}

public class SMSMsgReceiver
extends BroadcastReceiver {

@Override

public void onReceive(Context context, Intent intent) {

if (intent.getAction().equals(strACT)) {

StringBuilder sb = new StringBuilder();

Bundle bundle = intent.getExtras();

if (bundle != null) {

Object[] pdus = (Object[]) bundle.get("pdus");

SmsMessage[] msg = new SmsMessage[pdus.length];

for (int i = 0; i < pdus.length; i++) {

msg[i] = SmsMessage.createFromPdu((byte[]) pdus[i]);

}

for (SmsMessage currMsg : msg) {

sb.append("From:");

sb.append(currMsg.getDisplayOriginatingAddress());

sb.append("/nMessage:");

sb.append(currMsg.getDisplayMessageBody());

}

}

Intent i = new Intent(SvrId);

i.putExtra("PARAM", sb.toString());

sendBroadcast(i);

}

}

}

}

可以看到，前文中接收短信的代码被原封不动的复制到服务的代码内，唯一不同的就是服务中多了sendBroadcast()

二、修改BroadcastReceiver

package com.demo;

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.os.Bundle;

import android.widget.Toast;

public class MessageReceiver
extends BroadcastReceiver {

public static final String SvrId =
"RARNU.SERVICE.DEMO";

@Override

public void onReceive(Context context, Intent intent) {

if (intent.getAction().toString().equals(SvrId)) {

Bundle bund = intent.getExtras();

String strParam = "";

if (bund != null) {

strParam = bund.getString("PARAM");

}

Intent i = new Intent(context, MsgListen.class);

i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

Toast.makeText(context, strParam, Toast.LENGTH_SHORT).show();

context.startActivity(i);

}

}

}

收短信的代码被移到服务中了，那么BroadcastReceive自然也不再需要那段代码，直接从Extras中取得服务传来的字符串即可。

三、启动和终止

package com.demo;

import android.app.Activity;

import android.content.Intent;

import android.os.Bundle;

public class MsgListen
extends Activity {

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

}

@Override

protected void onResume() {

Intent i = new Intent(MsgListen.this, ListenService.class );

i.setFlags( Intent.FLAG_ACTIVITY_NEW_TASK );

startService(i);

super.onResume();

}

@Override

protected void onPause() {

Intent i = new Intent(MsgListen.this, ListenService.class);

stopService(i);

super.onPause();

}

}

在程序的onResume()事件中启动服务，在onPause()事件中停止服务

然后就可以尝试测试一下程序了，看看是不是程序关闭后，收到短信不会再弹提示了呢？