Android应用开发之（小技巧之LocalBroadcastManager）
Android v4 兼容包提供android.support.v4.content.LocalBroadcastManager工具类，帮助大家在自己的进程内进行局部广播发送与注册，使用它比直接通过sendBroadcast(Intent)发送系统全局广播有以下几点好处。
1 因广播数据在本应用范围内传播，你不用担心隐私数据泄露的问题。
2 不用担心别的应用伪造广播，造成安全隐患。
3 相比在系统内发送全局广播，它更高效。
使用方法 通过getInstance(Contextcontext)获取实例，demo如下：
/**
* Demonstrates the use of a LocalBroadcastManager to easily communicate
* data from a service to any other interested code.
*/
public class LocalServiceBroadcaster 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.local_service_broadcaster);
// This is where we print the data we get back.
final TextView callbackData = (TextView)findViewById(R.id.callback);
// Put in some initial text.
callbackData.setText("No broadcast received yet");
// We use this to send broadcasts within our local process.
mLocalBroadcastManager = LocalBroadcastManager.getInstance(this);
// We are going to watch for interesting local broadcasts.
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);
// Watch for button clicks.
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(LocalServiceBroadcaster.this, LocalService.class));
}
};
private OnClickListener mStopListener = new OnClickListener() {
public void onClick(View v) {
stopService(new Intent(LocalServiceBroadcaster.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;
}
}
}