Android udp多播失败，权限被拒绝

Question

尝试广播udp数据包时遇到问题。

08-22 16:36:13.359 E/UDPTester.UDPEndpoint(3657): IOException : Permission denied 
08-22 16:36:13.359 W/System.err(3657): java.net.SocketException: Permission denied 
08-22 16:36:13.369 W/System.err(3657):  at org.apache.harmony.luni.platform.OSNetworkSystem.send(Native Method) 
08-22 16:36:13.369 W/System.err(3657):  at dalvik.system.BlockGuard$WrappedNetworkSystem.send(BlockGuard.java:308) 
08-22 16:36:13.369 W/System.err(3657):  at org.apache.harmony.nio.internal.DatagramChannelImpl.send(DatagramChannelImpl.java:359) 
08-22 16:36:13.369 W/System.err(3657):  at zexing.udptester.UDPEndpoint.broadcast(UDPEndpoint.java:151) 
08-22 16:36:13.369 W/System.err(3657):  at zexing.udptester.MainActivity.onClickBroadcast(MainActivity.java:162) 
08-22 16:36:13.369 W/System.err(3657):  at java.lang.reflect.Method.invokeNative(Native Method) 
08-22 16:36:13.369 W/System.err(3657):  at java.lang.reflect.Method.invoke(Method.java:507) 
08-22 16:36:13.369 W/System.err(3657):  at android.view.View$1.onClick(View.java:2155) 
08-22 16:36:13.369 W/System.err(3657):  at android.view.View.performClick(View.java:2501) 
08-22 16:36:13.369 W/System.err(3657):  at android.view.View$PerformClick.run(View.java:9107) 
08-22 16:36:13.369 W/System.err(3657):  at android.os.Handler.handleCallback(Handler.java:587) 
08-22 16:36:13.369 W/System.err(3657):  at android.os.Handler.dispatchMessage(Handler.java:92) 
08-22 16:36:13.369 W/System.err(3657):  at android.os.Looper.loop(Looper.java:130) 
08-22 16:36:13.369 W/System.err(3657):  at android.app.ActivityThread.main(ActivityThread.java:3835) 
08-22 16:36:13.369 W/System.err(3657):  at java.lang.reflect.Method.invokeNative(Native Method) 
08-22 16:36:13.369 W/System.err(3657):  at java.lang.reflect.Method.invoke(Method.java:507) 
08-22 16:36:13.369 W/System.err(3657):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:847) 
08-22 16:36:13.369 W/System.err(3657):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605) 
08-22 16:36:13.369 W/System.err(3657):  at dalvik.system.NativeStart.main(Native Method) 

在AndroidManifest.xml中，我已经添加了这些权限。

<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/> 
<uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE"/> 
<uses-permission android:name="android.permission.INTERNET"/> 

另外，我播出前得到的组播锁

//创建组播锁@ Activity.onCreate

mcastLock = wifiManager.createMulticastLock("zexing.udptester.Multicast"); 

//广播中获取组播锁

mcastLock.acquire(); 
if (mcastLock.isHeld()) { 
    Log.i(TAG, "held multicast lock"); 
} 
udpEndpoint.broadcast(msg, port); 
Log.v(TAG, "broadcast " + msg + " to port : " + port); 
Log.d(TAG, "Release wifi Multicast lock to enable wifi UDP broadcast"); 
mcastLock.release(); 

// UdpEndpoint.broadcast

public void broadcast(String msg, int port) { 
    try { 
     if (broadcastChannel == null) { 
      Log.v(TAG, "opening write DatagramChannel"); 
      broadcastChannel = DatagramChannel.open(); 
      Log.v(TAG, "config write channel to non-blocking"); 
      broadcastChannel.configureBlocking(false); 
      Log.v(TAG, "reuse address"); 
      broadcastChannel.socket().setReuseAddress(true); 
      Log.v(TAG, "set broadcast to true"); 
      broadcastChannel.socket().setReuseAddress(true); 
      Log.v(TAG, "register broadcast Channel"); 
      broadcastChannel.register(selector, SelectionKey.OP_READ); 
      Log.v(TAG, "register broadcast channel successfully"); 
     } 
     if (msg.length() == 0) { 
      Log.w(TAG, "message to broadcast is null, skip sending"); 
     } 
     SocketAddress addr = new InetSocketAddress(InetAddress.getByName("255.255.255.255"), port); 
     Log.v(TAG, "allocate " + msg.length() + " bytes. msg.getBytes().length = " + msg.getBytes().length); 
     ByteBuffer bb = ByteBuffer.allocate(msg.length()); 
     bb.clear(); 
     bb.put(msg.getBytes()); 
     bb.flip(); 
     Log.v(TAG, "write channel broadcast " + msg + " to " + addr); 
     int bytes = broadcastChannel.send(bb, addr); 
     Log.v(TAG, "broadcast " + bytes + " bytes to " + addr); 
    } catch (UnknownHostException uhe) { 
     Log.e(TAG, "UnknownHostException : " + uhe.getMessage()); 
    } catch (IOException e) { 
     Log.e(TAG, "IOException : " + e.getMessage()); 
     e.printStackTrace(); 
    } 
} 

Answer 1

尝试发送广播subnet's广播地址例如：192.168.1.255，而不是255.255 ....方法，另外请确保您的端口超过1024个主要或仅仅端口0，系统将选择一个适合你