android ContentObserver,BroadcastReceiver，Handler各自用法

今天在修改bug时，找到一文件packages\apps\Settings\src\com\android\settings\notification\NotificationSettings.java这个类经常修改，但之前都是有什么问题就修改一下问题，并未对该文件做仔细阅读，今天一个bug原本只需要在类中现有的一广播中注册广播动作（AudioManager.RINGER_MODE_CHANGED_ACTION），然后在接收到该广播时做相应的处理即可，但在系统发出广播后死活接收到不该 广播，就这问题弄了一个上午，最后还是一个同事帮忙解决，文件中原有的广播注册：

final IntentFilter filter = new IntentFilter();
filter.addAction(NotificationManager.ACTION_EFFECTS_SUPPRESSOR_CHANGED);
filter.addAction(AudioManager.INTERNAL_RINGER_MODE_CHANGED_ACTION);

filter.addDataScheme("file");
mContext.registerReceiver(this, filter);

我添加后：

 final IntentFilter filter = new IntentFilter();
filter.addAction(NotificationManager.ACTION_EFFECTS_SUPPRESSOR_CHANGED);
filter.addAction(AudioManager.INTERNAL_RINGER_MODE_CHANGED_ACTION);filter.addAction(AudioManager.RINGER_MODE_CHANGED_ACTION);

filter.addDataScheme("file");
mContext.registerReceiver(this, filter);

就这么简单加入一个系统铃声模式的改变广播，弄了一上午都接收不到系统发出的该广播事件，且确认系统有发出该广播，该广播也成功注册了，但就是接收到不广播，一同事说要不你把：

filter.addDataScheme("file");

去掉看看，抱着试试看的心态一试，果然可以了，后面百度才知道加入与不加入filter.addDataScheme("file");有区别的，联系到广播的显式广播与隐式广播，广播的这两个方式区别这里就不做详细说明的，大家可以自己百度了解一下，

（2）ContentObserver,BroadcastReceiver，Handler各自用法，感觉下面这代码写的很不错，现记录下来，声明：private final H mHandler = new H();private final SettingsObserver mSettingsObserver = new SettingsObserver();private final Receiver mReceiver = new Receiver();调用：@Overridepublic void onResume() {super.onResume();refreshNotificationListeners();lookupRingtoneNames();mSettingsObserver.register(true);mReceiver.register(true);updateRingOrNotificationPreference();updateEffectsSuppressor();for (VolumeSeekBarPreference volumePref : mVolumePrefs) {volumePref.onActivityResume();}}@Overridepublic void onPause() {super.onPause();mVolumeCallback.stopSample();mSettingsObserver.register(false);mReceiver.register(false);}实现private final class SettingsObserver extends ContentObserver {private final Uri VIBRATE_WHEN_RINGING_URI =Settings.System.getUriFor(Settings.System.VIBRATE_WHEN_RINGING);private final Uri NOTIFICATION_LIGHT_PULSE_URI =Settings.System.getUriFor(Settings.System.NOTIFICATION_LIGHT_PULSE);private final Uri LOCK_SCREEN_PRIVATE_URI =Settings.Secure.getUriFor(Settings.Secure.LOCK_SCREEN_ALLOW_PRIVATE_NOTIFICATIONS);private final Uri LOCK_SCREEN_SHOW_URI =Settings.Secure.getUriFor(Settings.Secure.LOCK_SCREEN_SHOW_NOTIFICATIONS);public SettingsObserver() {super(mHandler);}public void register(boolean register) {final ContentResolver cr = getContentResolver();if (register) {cr.registerContentObserver(VIBRATE_WHEN_RINGING_URI, false, this);cr.registerContentObserver(NOTIFICATION_LIGHT_PULSE_URI, false, this);cr.registerContentObserver(LOCK_SCREEN_PRIVATE_URI, false, this);cr.registerContentObserver(LOCK_SCREEN_SHOW_URI, false, this);} else {cr.unregisterContentObserver(this);}}@Overridepublic void onChange(boolean selfChange, Uri uri) {super.onChange(selfChange, uri);if (VIBRATE_WHEN_RINGING_URI.equals(uri)) {updateVibrateWhenRinging();}if (NOTIFICATION_LIGHT_PULSE_URI.equals(uri)) {updatePulse();}if (LOCK_SCREEN_PRIVATE_URI.equals(uri) || LOCK_SCREEN_SHOW_URI.equals(uri)) {updateLockscreenNotifications();}}}private final class H extends Handler {private static final int UPDATE_PHONE_RINGTONE = 1;private static final int UPDATE_NOTIFICATION_RINGTONE = 2;private static final int STOP_SAMPLE = 3;private static final int UPDATE_EFFECTS_SUPPRESSOR = 4;private static final int UPDATE_RINGER_MODE = 5;private H() {super(Looper.getMainLooper());}@Overridepublic void handleMessage(Message msg) {switch (msg.what) {case UPDATE_PHONE_RINGTONE:mPhoneRingtonePreference.setSummary((CharSequence) msg.obj);break;case UPDATE_NOTIFICATION_RINGTONE:mNotificationRingtonePreference.setSummary((CharSequence) msg.obj);break;case STOP_SAMPLE:mVolumeCallback.stopSample();break;case UPDATE_EFFECTS_SUPPRESSOR:updateEffectsSuppressor();break;case UPDATE_RINGER_MODE:updateRingerMode();break;}}}private class Receiver extends BroadcastReceiver {private boolean mRegistered;public void register(boolean register) {if (mRegistered == register) return;if (register) {final IntentFilter filter = new IntentFilter(); filter.addAction(NotificationManager.ACTION_EFFECTS_SUPPRESSOR_CHANGED); filter.addAction(AudioManager.INTERNAL_RINGER_MODE_CHANGED_ACTION);mContext.registerReceiver(this, filter);} else {mContext.unregisterReceiver(this);}mRegistered = register;}@Overridepublic void onReceive(Context context, Intent intent) {final String action = intent.getAction();if (NotificationManager.ACTION_EFFECTS_SUPPRESSOR_CHANGED.equals(action)) {mHandler.sendEmptyMessage(H.UPDATE_EFFECTS_SUPPRESSOR);} else if (AudioManager.INTERNAL_RINGER_MODE_CHANGED_ACTION.equals(action)) {mHandler.sendEmptyMessage(H.UPDATE_RINGER_MODE);}}}