android - 同时在同一个端口上使用 UDP server-client

Question

我有一个应用程序可以处理 UDP 数据包。所以我想在同一个应用程序中同时发送和接收 UDP 数据包。这是真的吗？现在它完美地工作，但分开。 代码 fragment : UDP 服务器:

public class UDPServer {    
DatagramPacket packet;  
DatagramSocket socket;      
static int port = 11111;    
private boolean isRun = false;
private String message = "";
private int broadcastInterval;  
private Context context;

public boolean IsRunUDPServer(){
    return isRun;
}
public void StopBroadcasting(){
    isRun = false;      
}
public void StartBroadcasting(String message, int broadcastInterval){
    isRun = true;
    this.message = message;
    this.broadcastInterval = broadcastInterval;     
    new Thread(runner).start();     
}

Runnable runner = new Runnable() {      
    public void run() {
        while(isRun){               
            try {
                //Sending(message);
                SendBroadcastMessageOverWiFi(message);
                Thread.sleep(broadcastInterval);
                Log.e("SendBroadcastMessageOverWiFi", message);
            } catch (InterruptedException e) {                  
                e.printStackTrace();
            } catch (IOException e) {                   
            }
        }
        if(socket!=null){
            socket.disconnect();
            socket.close();             
        }           
    }
};

public UDPServer(Context context) {
    this.context=context;       
}

private InetAddress getBroadcastAddress() throws IOException {      
    WifiManager wifi = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
    DhcpInfo dhcp = wifi.getDhcpInfo();
    // handle null somehow
    if(dhcp==null){ return null; }
    int broadcast = (dhcp.ipAddress & dhcp.netmask) | ~dhcp.netmask;
    byte[] quads = new byte[4];
    for (int k = 0; k < 4; k++)
      quads[k] = (byte) ((broadcast >> k * 8) & 0xFF);
    return InetAddress.getByAddress(quads);
}

private void SendBroadcastMessageOverWiFi(String message) throws IOException{
    InetAddress addr = getBroadcastAddress();
    if(addr!=null){
        if(socket==null){
            socket = new DatagramSocket(port);          
            socket.setBroadcast(true);              
        }
        DatagramPacket packet = new DatagramPacket(message.getBytes(), message.getBytes().length,
            addr, port);
        socket.send(packet);                
    }       
}}

UDP 客户端:

public class UDPClient {
MulticastSocket socket;
InetAddress groupAddress;
DatagramPacket packet;
byte[] buffer;

private static final int UDP_SERVER_PORT = 11111;
private static final int MAX_UDP_DATAGRAM_LEN = 32768;      

public interface OnReceiveDataListener{
    public abstract void onReceiveData(String data);
}

private OnReceiveDataListener ReceiveDataListener = null;   

public void setReceiveDataListener(OnReceiveDataListener ReceiveDataListener) {
    this.ReceiveDataListener = ReceiveDataListener;
}

public OnReceiveDataListener getReceiveDataListener() {
    return ReceiveDataListener;
}

private boolean isRun = false;  
private Thread broadcastReceiver;
public void StopReceiving(){
    isRun = false;      
}
public void StartReceiving(){
    isRun = true;           
    buffer = new byte[4096];
    broadcastReceiver = new Thread(runner);     
    broadcastReceiver.start();
}
Runnable runner = new Runnable() {      
    @Override
    public void run() {
        while(isRun){               

            String lText;
            packet = new DatagramPacket(buffer, buffer.length);             
            DatagramSocket ds = null;
            try {
                ds = new DatagramSocket(UDP_SERVER_PORT);                   
                ds.receive(packet);
                lText = new String(packet.getData(), 0, packet.getLength());
                Log.i("UDP packet received", lText+"  "+packet.getLength()+"  "+packet.getData().length);
                if(getReceiveDataListener()!=null)
                    getReceiveDataListener().onReceiveData(lText);

            } catch (SocketException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if (ds != null) {
                    ds.close();
                }
            }
        }           
    }
};}

如果我启动服务器，客户端将无法接收 udp 数据包。 请帮我。谢谢。

Answer 1

一次只有一个套接字(在一个进程中)可以绑定(bind)到给定的 UDP 端口。不允许两个套接字绑定(bind)到同一个 UDP 端口号。

在大多数情况下，没有理由将客户端绑定(bind)到特定端口。相反，指定端口 0 (INADDR_ANY)，系统将分配一个未使用的动态端口。