安卓多播地址已在使用中

Question

我有一个简单的 SSDP 搜索，但有时我会收到"使用中的地址"错误

public void search(String service, CallbackContext callbackContext) throws IOException {
final int SSDP_PORT = 1900;
final int SSDP_SEARCH_PORT = 1901;
final String SSDP_IP = "239.255.255.250";
int TIMEOUT = 3000;
InetSocketAddress srcAddress = new InetSocketAddress(SSDP_SEARCH_PORT);
InetSocketAddress dstAddress = new InetSocketAddress(InetAddress.getByName(SSDP_IP), SSDP_PORT);
// Clear the cached Device List every time a new search is called
mDeviceList = new JSONArray();
// M-Search Packet
StringBuffer discoveryMessage = new StringBuffer();
discoveryMessage.append("M-SEARCH * HTTP/1.1rn");
discoveryMessage.append("HOST: " + SSDP_IP + ":" + SSDP_PORT + "rn");
discoveryMessage.append("ST:"+service+"rn");
//discoveryMessage.append("ST:ssdp:allrn");
discoveryMessage.append("MAN: "ssdp:discover"rn");
discoveryMessage.append("MX: 2rn");
discoveryMessage.append("rn");
System.out.println("Request: " + discoveryMessage.toString() + "n");
byte[] discoveryMessageBytes = discoveryMessage.toString().getBytes();
DatagramPacket discoveryPacket = new DatagramPacket(discoveryMessageBytes, discoveryMessageBytes.length, dstAddress);
// Send multi-cast packet
MulticastSocket multicast = null;
try {
multicast = new MulticastSocket(null);
multicast.bind(srcAddress);
multicast.setTimeToLive(4);
multicast.send(discoveryPacket);
} finally {
multicast.disconnect();
multicast.close();
}
// Create a socket and wait for the response
DatagramSocket wildSocket = null;
DatagramPacket receivePacket;
try {
wildSocket = new DatagramSocket(SSDP_SEARCH_PORT);
wildSocket.setSoTimeout(TIMEOUT);
while (true) {
try {
receivePacket = new DatagramPacket(new byte[1536], 1536);
wildSocket.receive(receivePacket);
String message = new String(receivePacket.getData());   
try {
JSONObject device = new JSONObject();
device.put("USN", parseHeaderValue(message, "USN"));
device.put("LOCATION", parseHeaderValue(message, "LOCATION"));
device.put("ST", parseHeaderValue(message, "ST"));
device.put("Server", parseHeaderValue(message, "Server"));
createServiceObjWithXMLData(parseHeaderValue(message, "LOCATION"), device);
} catch (JSONException e) {
e.printStackTrace();
}
} catch (SocketTimeoutException e) {
callbackContext.success(mDeviceList);
break;
}
}
} finally {
if (wildSocket != null) {
wildSocket.disconnect();
wildSocket.close();
}
}
}

如何将其设置为动态端口，而不是 1901？

我尝试做multicast.setReuseAddress(true);但它仍然给出相同的错误

我看了这个SO，它暗示了同样的事情，但就我而言，它没有按预期工作。我不断收到同样的错误。

如何解决此问题？

Answer 1

这一行：

组播 = 新的多播套接字(空(;

应更改为：

multicast = new MulticastSocket();
multicast.setReuseAddress(true);
multicast.bind(srcAddress);    

这将取决于平台。如果 getReuseAddress(( 返回 false，则您的设备不支持。https://developer.android.com/reference/java/net/DatagramSocket.html#setReuseAddress(布尔值(

Note: This functionality is not supported by all existing platforms, so it is implementation specific whether this option will be ignored or not. However, if it is not supported then getReuseAddress() will always return false.