发表于2个月前(2014-11-03 22:05) 阅读（37） | 评论（0） 0人收藏此文章, 我要收藏
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摘要 android中广播的作用非常大，对程序的运行起着非常重要的作用
Android中BroadcastReceiver主要用途有
发送通知，更新UI或者数据，应用程序间相互通信，监听系统状态（比如开机，网络等）
Android中BroadcasetReceiver的注册方式
manifest清单文件中的全局注册
按照生命周期，在Service或者Activity中使用代码注册
manifest的注册方式
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<receiver android:name="com.sample.test.MyBroadcastReciever">
<intent-filter>
<action android:name="com.sample.test.ACTION_DO_SOMETHING"></action>
<action android:name="android.intent.ACTION_WIFI_STATE_CHANGED"></action>
</intent-filter>
</receiver>
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使用代码注册
SampleActivity
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private MyReceiver receiver;
@Override public void onStart() {
super.onStart();
receiver = new MyReceiver();
IntentFilter filter = new IntentFilter();
filter.addAction("android.intent.action.MY_BROADCAST");
registerReceiver(receiver, filter);
}@Overridepublic void onStop(){
super.onStop();
unregisterReceiver(receiver);
} |
Android中发送广播的方式
普通广播：无论优先级大小，将发送给所有监听Action="com.test.sample.action"的广播,内容不可被修改，无传递性。
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Intent intent = new Intent( "com.test.sample.action");
sendBroadcast(intent); |
异步（黏性）广播: 当处理完之后的Intent ，依然存在，这时候registerReceiver(BroadcastReceiver, IntentFilter) 还能收到他的值，直到你把它去掉 , 无传递性 , 无法终止(abort())广播。
发这个广播需要权限<uses-permission android:name="android.permission.BROADCAST_STICKY" />
去掉是用这个方法removeStickyBroadcast(intent); 但别忘了在执行这个方法的应用里面 AndroidManifest.xml 同样要加上面的权限；
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sendStickyOrderedBroadcast(intent, resultReceiver, scheduler, initialCode, initialData, initialExtras)
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有序广播：
按照接收者的优先级顺序接收广播 , 优先级别在 intent-filter 中的 priority 中声明 ,-1000 到1000 之间 ，值越大 优先级越高 。可以终止广播意图的继续传播 ， 接收者可以篡改内容，具有传递性。
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sendBroadcast(intent); |
Android中的BroadcastReceiver可以用来发送信息到另一个广播，这种方式可实现程序或者进程间的通行。
上面回顾了一下Android的广播用例，总体来说安全性都不太好，因此只适用于安全性较低的数据传递，或者页面更新。
在android-support-v4.jar中引入了LocalBroadcastManager，称为局部通知管理器，这种通知的好处是安全性高，效率也高，适合局部通信，可以用来代替Handler更新UI
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public class LocalServiceBroadcasterActivity extends Activity {
static final String ACTION_STARTED = "com.example.android.supportv4.STARTED";
static final String ACTION_UPDATE = "com.example.android.supportv4.UPDATE";
static final String ACTION_STOPPED = "com.example.android.supportv4.STOPPED";
LocalBroadcastManager mLocalBroadcastManager;
BroadcastReceiver mReceiver;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final TextView callbackData = (TextView) findViewById(R.id.callback);
callbackData.setText("No broadcast received yet");
mLocalBroadcastManager = LocalBroadcastManager.getInstance(this);
IntentFilter filter = new IntentFilter();
filter.addAction(ACTION_STARTED);
filter.addAction(ACTION_UPDATE);
filter.addAction(ACTION_STOPPED);
mReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(ACTION_STARTED)) {
callbackData.setText("STARTED");
} else if (intent.getAction().equals(ACTION_UPDATE)) {
callbackData.setText("Got update: " + intent.getIntExtra("value", 0));
} else if (intent.getAction().equals(ACTION_STOPPED)) {
callbackData.setText("STOPPED");
}
}
};
mLocalBroadcastManager.registerReceiver(mReceiver, filter);
Button button = (Button) findViewById(R.id.start);
button.setOnClickListener(mStartListener);
button = (Button) findViewById(R.id.stop);
button.setOnClickListener(mStopListener);
}
@Override
protected void onDestroy() {
super.onDestroy();
mLocalBroadcastManager.unregisterReceiver(mReceiver);
}
private OnClickListener mStartListener = new OnClickListener() {
public void onClick(View v) {
startService(new Intent(LocalServiceBroadcasterActivity.this, LocalService.class));
}
};
private OnClickListener mStopListener = new OnClickListener() {
public void onClick(View v) {
stopService(new Intent(LocalServiceBroadcasterActivity.this, LocalService.class));
}
};
public static class LocalService extends Service {
LocalBroadcastManager mLocalBroadcastManager;
int mCurUpdate;
static final int MSG_UPDATE = 1;
Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_UPDATE: {
mCurUpdate++;
Intent intent = new Intent(ACTION_UPDATE);
intent.putExtra("value", mCurUpdate);
mLocalBroadcastManager.sendBroadcast(intent);
Message nmsg = mHandler.obtainMessage(MSG_UPDATE);
mHandler.sendMessageDelayed(nmsg, 1000);
}
break;
default:
super.handleMessage(msg);
}
}
};
@Override
public void onCreate() {
super.onCreate();
mLocalBroadcastManager = LocalBroadcastManager.getInstance(this);
}
public int onStartCommand(Intent intent, int flags, int startId) {
// Tell any local interested parties about the start.
mLocalBroadcastManager.sendBroadcast(new Intent(ACTION_STARTED));
// Prepare to do update reports.
mHandler.removeMessages(MSG_UPDATE);
Message msg = mHandler.obtainMessage(MSG_UPDATE);
mHandler.sendMessageDelayed(msg, 1000);
return ServiceCompat.START_STICKY;
}
@Override
public void onDestroy() {
super.onDestroy();
// Tell any local interested parties about the stop.
mLocalBroadcastManager.sendBroadcast(new Intent(ACTION_STOPPED));
// Stop doing updates.
mHandler.removeMessages(MSG_UPDATE);
}
@Override
public IBinder onBind(Intent intent) {
return null;
}
}
} |
摘自：http://my.oschina.net/ososchina/blog/340339