如何在android上接收广播数据包
我正在尝试实现我的应用程序能够接收一些广播消息。一台设备向192.168.2.255发送消息。我在Wireshark上看到了这一点。我的应用程序应该会收到这些消息,但尚未运行。这是我的代码:如何在android上接收广播数据包,android,broadcast,Android,Broadcast,我正在尝试实现我的应用程序能够接收一些广播消息。一台设备向192.168.2.255发送消息。我在Wireshark上看到了这一点。我的应用程序应该会收到这些消息,但尚未运行。这是我的代码: int port = 3123; // Create a socket to listen on the port. DatagramSocket dsocket = new DatagramSocket(port); dsocket.setBroadcas
int port = 3123;
// Create a socket to listen on the port.
DatagramSocket dsocket = new DatagramSocket(port);
dsocket.setBroadcast(true);
// Create a buffer to read datagrams into. If a
// packet is larger than this buffer, the
// excess will simply be discarded!
byte[] buffer = new byte[1024];
// Create a packet to receive data into the buffer
DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
// Now loop forever, waiting to receive packets and printing them.
while (true) {
// Wait to receive a datagram
dsocket.receive(packet);
// Convert the contents to a string, and display them
String msg = new String(buffer, 0, packet.getLength());
System.out.println(packet.getAddress().getHostName() + ": " + msg);
// Reset the length of the packet before reusing it.
packet.setLength(buffer.length);
res = msg;
Log.d("mainGate_bc", res);
}
} catch (Exception e) {
System.err.println(e);
}
该程序卡在dsocket.receive(数据包)线上。当另一台设备发送数据包时,我的应用程序中没有任何内容
我尝试了以下权限:
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>
知道它为什么不起作用吗?还有其他权限吗?Android设备上的设置?这个问题与 显然,除非获得多播锁,否则广播数据包都会被过滤掉 因此,您需要以下代码:
WifiManager wm = null;
MulticastLock multicastLock = null;
@Override
protected void onResume() {
super.onResume();
if(wm == null)wm = (WifiManager)getSystemService(Context.WIFI_SERVICE);
if(multicastLock == null){
multicastLock = wm.createMulticastLock("stackoverflow for the win");
multicastLock.setReferenceCounted(true);
}
if(multicastLock != null && !multicastLock.isHeld()) multicastLock.acquire();
}
@Override
protected void onPause() {
super.onPause();
if(multicastLock != null && multicastLock.isHeld()) multicastLock.release();
}
<uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
WifiManager wm=null;
MulticastLock MulticastLock=null;
@凌驾
受保护的void onResume(){
super.onResume();
if(wm==null)wm=(WifiManager)getSystemService(Context.WIFI_服务);
if(多播锁==null){
multicastLock=wm.createMulticastLock(“stackoverflow for the win”);
multicastLock.setReferenceCounted(真);
}
if(multicastLock!=null&&!multicastLock.ishell())multicastLock.acquire();
}
@凌驾
受保护的void onPause(){
super.onPause();
if(multicastLock!=null&&multicastLock.ishell())multicastLock.release();
}
谢谢,但结果相同。代码是否克服了对receive()
的阻塞调用?如果没有,请查看以定期中断阻塞调用。它不会。但我也不想打断你的接收。我想接收似乎没有到达我的应用程序的现有消息。请尝试DatagramSocket dsocket=new DatagramSocket(null);dsocket.setReuseAddress(真);dsocket.Roadcast(真实);绑定(新的InetSocketAddress(端口))代码>很遗憾,没有更改。