Question

我正在尝试构建一个程序，该程序能够在一个端口上连接到客户端的TCP服务器，同时还能够在其他端口上传递和侦听UDP数据包中的数据。

我充当TCP服务器并从TCP客户端获取命令，然后通过UDP将它们传递给其他设备。我还必须在UDP中侦听来自设备的响应，然后将它们传递回TCP客户端。我一直试图通过创建2个线程来实现这一点，一个用于连接到TCP客户端，同时在另一个线程上使用不同的端口持续监听UDP数据包。

从TCP客户端获取数据并将其发送到UDP设备时，它可以正常工作。但是当我尝试从UDP设备收集结果并将它们发送回TCP客户端时。该程序无法立即发回数据。它等待TCP客户端发送数据。这意味着我有一个填充结果的向量队列，但我必须等待TCP客户端与我通信才能发回结果。

当向量中有数据时，有没有办法通知TCP线程发送数据？

public class TCPUDP2 {

final protected static char[] hexArray = "0123456789ABCDEF".toCharArray();  
final protected static int udplistenport=1002;
final protected static int tcplistenport=1001;
private static Vector<String> udprecv=new Vector();     //UDP result queue


public static String bytesToHex(byte[] bytes) {   //convert byte[] to string
    char[] hexChars = new char[bytes.length * 2];
    for ( int j = 0; j < bytes.length; j++ ) {
        int v = bytes[j] & 0xFF;
        hexChars[j * 2] = hexArray[v >>> 4];
        hexChars[j * 2 + 1] = hexArray[v & 0x0F];
    }
    return new String(hexChars);
}
public static byte[] hexStringToByteArray(String s) {               //Convert string to byte[]
    int len = s.length();
    byte[] data = new byte[len / 2];
    for (int i = 0; i < len; i += 2) {
        data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
                             + Character.digit(s.charAt(i+1), 16));
    }
    return data;
}

public static void main(String[] args) throws IOException { 

     Thread udplisten = new Thread() {
         public void run() {
                try {


                    DatagramSocket dsocket = new DatagramSocket(udplistenport);
                    System.out.println("UDP Listening");

                    byte[] buffer = new byte[1024];

                    DatagramPacket packet = new DatagramPacket(buffer, buffer.length);


                    while (true) {

                      dsocket.receive(packet);

                      byte[] newbuffer= new byte[packet.getLength()];

                      for(int i =0;i<packet.getLength();i++)
                        newbuffer[i]=buffer[i];


                      System.out.println(" UDP from "+packet.getAddress()+" "+bytesToHex(newbuffer)+" "+new java.util.Date());
                      udprecv.add(bytesToHex(newbuffer));
                      System.out.println(udprecv);


                      //String msg = new String(buffer, 0, packet.getLength());
                      //System.out.println(msg);  


                      // Reset the length of the packet before reusing it.
                      packet.setLength(buffer.length);
                    }
                  } catch (Exception e) {
                    System.err.println(e);
                  }
         }
     }; 

     udplisten.start();

     Thread tcpplisten = new Thread() {
         public void run() {
             System.out.println("TCP Listening");
             ByteArrayOutputStream serverinput=new ByteArrayOutputStream();

             try{

                 ServerSocket ss = new ServerSocket(tcplistenport);     // establish tcp server


                 for(;;) {

                  Socket sc  = ss.accept();               
                 System.out.println(sc.getLocalSocketAddress().toString()+" "+new java.util.Date());   
                 OutputStream os = sc.getOutputStream();    
                 InputStream in = sc.getInputStream(); 
                 int len=0;
                 byte[] buf=new byte[2048];   

                 while( !(udprecv.isEmpty())){
                    String first=udprecv.firstElement();
                    byte[] tcpsend=hexStringToByteArray(first);
                   os.write(tcpsend);//Send to Client
                   os.flush();
                   System.out.println("Sent by TCP "+bytesToHex(tcpsend)+" "+new java.util.Date());
                   udprecv.removeElementAt(0);
                }


                 while ((len = in.read(buf))>=0)
                 {
                     serverinput.write(buf, 0, len);


                    System.out.println("From TCP "+bytesToHex(serverinput.toByteArray())+" "+sc.getLocalSocketAddress().toString());
                    MessageCreator cannonball=new MessageCreator("02","003F", bytesToHex(serverinput.toByteArray()));
                    byte[] cmd= cannonball.create(); 

                    String udpip="127.0.0.1";
                    int udpport=8888;
                    UDPSender cannon =new UDPSender(udpip,udpport,cmd); 
                    System.out.println("Sent by UDP "+bytesToHex(cmd)+" "+udpip+":"+udpport);
                    cannon.fire();


                    serverinput.reset();  

                    while( !(udprecv.isEmpty())){
                        String first=udprecv.firstElement();
                        byte[] tcpsend=hexStringToByteArray(first);
                       os.write(tcpsend);//Send to Client
                       os.flush();
                       System.out.println("Sent by TCP "+bytesToHex(tcpsend));
                       udprecv.removeElementAt(0);                                                                              
                    }

                 }


                // os.close();                                // Close stream
                // sc.close();                                // Shutdown TCP server

             }
             }catch(Exception e){
                 System.err.println(e);

             }


         }
     };
     tcpplisten.start();


   }
   }

Java TCP和UDP服务器同时工作

0 个答案: