关于Intent.FLAG_RECEIVER_REPLACE_PENDING

本文探讨了BroadcastReceiver中FLAG_RECEIVER_REPLACE_PENDING标记的使用及其对Intent处理的影响。解释了该标记如何使后续Intent覆盖之前已有的Intent,并分析了FLAG_RECEIVER_REGISTERED_ONLY标记对AndroidManifest.xml中定义的Receiver接收特定Intent的影响。

 /**

     * If set, when sending a broadcast the new broadcast will replace

     * any existing pending broadcast that matches it.  Matching is defined

     * by {@link Intent#filterEquals(Intent) Intent.filterEquals} returning

     * true for the intents of the two broadcasts.  When a match is found,

     * the new broadcast (and receivers associated with it) will replace the

     * existing one in the pending broadcast list, remaining at the same

     * position in the list.

     *

     * <p>This flag is most typically used with sticky broadcasts, which

     * only care about delivering the most recent values of the broadcast

     * to their receivers.

     */

    public static final int FLAG_RECEIVER_REPLACE_PENDING = 0x20000000;

 

前段时间在开发的过程中发现了一个很奇怪的问题, 就是在一个BroadcastReceiver里 接收一个Intent 的消息, 但是并不是这个Intent 的所有消息都可以接收得到。

后来查了一下发送Intent 的地方, 才发现这个Intent 加了一个Flag ,FLAG_RECEIVER_REPLACE_PENDING, 这个flag 将会将之前的Intent 替代掉。加了这个flag,在发送一系列的这样的Intent 之后, 中间有些Intent 有可能在你还没有来得及处理的时候, 就被替代掉了。

 

另外, 还有一个Flag: FLAG_RECEIVER_REGISTERED_ONLY

如果Intent 加了这个Flag, 那么在Androidmanifest.xml 里定义的Receiver 是接收不到这样的Intent 的。

956 protected void updateUsbStateBroadcastIfNeeded(long functions) { 957 // send a sticky broadcast containing current USB state 958 Intent intent = new Intent(UsbManager.ACTION_USB_STATE); 959 intent.addFlags(Intent.FLAG_RECEIVER_REPLACE_PENDING 960 | Intent.FLAG_RECEIVER_INCLUDE_BACKGROUND 961 | Intent.FLAG_RECEIVER_FOREGROUND); 962 //#ifdef OPLUS_FEATURE_BROADCAST_OPTIMIZE 963 //PeiRunsheng@ANDROID.AMS.1051046, 2016/05/12, Add for optimize broadcast: 964 intent.addFlags(IIntentExt.FLAG_RECEIVER_QUEUE_PRIOR); 965 //#endif /* OPLUS_FEATURE_BROADCAST_OPTIMIZE */ 966 intent.putExtra(UsbManager.USB_CONNECTED, mConnected); 967 intent.putExtra(UsbManager.USB_HOST_CONNECTED, mHostConnected); 968 intent.putExtra(UsbManager.USB_CONFIGURED, mConfigured); 969 intent.putExtra(UsbManager.USB_DATA_UNLOCKED, 970 isUsbTransferAllowed() && isUsbDataTransferActive(mCurrentFunctions)); 971 972 long remainingFunctions = functions; 973 while (remainingFunctions != 0) { 974 intent.putExtra(UsbManager.usbFunctionsToString( 975 Long.highestOneBit(remainingFunctions)), true); 976 remainingFunctions -= Long.highestOneBit(remainingFunctions); 977 } 978 979 // send broadcast intent only if the USB state has changed 980 if (!isUsbStateChanged(intent)) { 981 if (DEBUG) { 982 Slog.d(TAG, "skip broadcasting " + intent + " extras: " + intent.getExtras()); 983 } 984 return; 985 } 986 987 if (DEBUG) Slog.d(TAG, "broadcasting " + intent + " extras: " + intent.getExtras()); 988 sendStickyBroadcast(intent); 989 mBroadcastedIntent = intent; 990 }
最新发布
07-30
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