每个客户端请求的Java DatagramSocket不同线程

我正在从事一个Java项目，其中客户端通过DatagramSocket发送一个基本计算（例如5+6），服务器需要回复结果。目标是让不同的线程计算每个不同的客户端请求。到目前为止，我有以下代码：

客户：

import java.net.*;
import java.io.*; 
public class UDPClient {
    public static void main (String args[]){
        DatagramSocket aSocket = null;
        int input=-1;
        String operation=null;
        while(input!=0){
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            System.out.println("Select an option");
            System.out.println("1. Do a basic calculation");
            System.out.println("0. Exit ");
            try{
                input = Integer.parseInt(br.readLine());
                if(input>1 | input<0)throw new Exception("Error");
            }
              catch(Exception e){
                    System.out.println("Wrong selection...Try again \n");
                }
            if(input==1)
            {
                    System.out.println("Give operator symbol (+,-,*,/) ");
                    try{
                        String operator = br.readLine();
                        if(!(operator.matches("[*]|[+]|[/]|[-]")))throw new Exception("Error");
                        System.out.println("Give first number");
                        int first = Integer.parseInt(br.readLine());
                        System.out.println("Give second number");
                        int second = Integer.parseInt(br.readLine());
                        operation =  first+":"+operator+":"+second;
        send:
            try{
                aSocket = new DatagramSocket();
                byte [] m = operation.getBytes();
                InetAddress aHost = InetAddress.getByName(args[1]);
                int serverPort = 6789;
                DatagramPacket request = new DatagramPacket(m, m.length, aHost, serverPort);
                aSocket.send(request);
                aSocket.setSoTimeout(10000); // SocketTimeout happens here
                byte[]buffer = new byte[1000];
                DatagramPacket reply = new DatagramPacket(buffer, buffer.length);
                aSocket.receive(reply);
                System.out.println("Reply:" + new String(reply.getData()));

            }
            catch (SocketTimeoutException e) {
                System.out.println("Server reply timeout");
                break send;  //If Timeout happens, send request again
            }
            catch(SocketException e){
                System.out.println("Socket: " + e.getMessage());
            }
            catch(IOException e){
                    System.out.println("IO: " + e.getMessage());
            }
            finally {if (aSocket!=null) aSocket.close();}
            }
            catch(Exception e){
                System.out.println("Wrong input...Try again \n"); 
            }

        }//End of if
    }//end of while

    }
}

import java.net.*;
import java.io.*; 
public class UDPClient {
    public static void main (String args[]){
        DatagramSocket aSocket = null;
        int input=-1; //User Input from menu
        String operation=null; //keeps the calculation operation in String form
        int resends=0; //NACK counter
        while(input!=0){
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            System.out.println("Select an option");
            System.out.println("1. Do a basic calculation");
            System.out.println("0. Exit ");
            try{
                input = Integer.parseInt(br.readLine());
                if(input>1 | input<0)throw new Exception("Error");
            }
              catch(Exception e){
                    System.out.println("Wrong selection...Try again \n");
                }
            if(input==1)
            {
                    System.out.println("Give operator symbol (+,-,*,/) ");
                    try{
                        String operator = br.readLine();
                        if(!(operator.matches("[*]|[+]|[/]|[-]")))throw new Exception("Error");
                        System.out.println("Give first number");
                        int first = Integer.parseInt(br.readLine());
                        System.out.println("Give second number");
                        int second = Integer.parseInt(br.readLine());
                        operation =  first+":"+operator+":"+second;
                    }
                    catch(Exception e){
                        System.out.println("Wrong input...Try again \n"); 
                        System.out.println(e.getMessage());
                    }
           while(true){
                try{
                    if(resends==3){ // At 3 resends break loop
                        resends=0;
                        break;              
                    }
                    aSocket = new DatagramSocket();
                    byte [] m = operation.getBytes();
                    InetAddress aHost = InetAddress.getByName(args[1]);
                    int serverPort = 6789;
                    DatagramPacket request = new DatagramPacket(m, m.length, aHost, serverPort);
                    aSocket.send(request);
                    resends++;//counting times we send this message
                    aSocket.setSoTimeout(30000); // Setting timeout for socket (30 sec)
                    byte[]buffer = new byte[1000];
                    DatagramPacket reply = new DatagramPacket(buffer, buffer.length);
                    aSocket.receive(reply);
                    System.out.println("Reply:" + new String(reply.getData()));
                    if(reply!=null)break; // If you get a reply, break loop

                }
                catch (SocketTimeoutException e) {
                    System.out.println("Server reply timeout");         

                }
                catch(SocketException e){
                    System.out.println("Socket: " + e.getMessage());
                }
                catch(IOException e){
                        System.out.println("IO: " + e.getMessage());
                }
                finally {if (aSocket!=null) aSocket.close();}              
           }// end of send while loop

        }//End of if
            else if (input==0)
                System.out.println("Exiting UDP Client.....");

     }//end of while
  }//end of main

}//end of Class

我有两个基本问题

1） 如果我从客户端发送第二个请求（第一个请求执行得很好），则会导致服务器输出套接字关闭错误消息

2） 正如您在服务器端看到的，我目前已经对sock.send（reply）进行了注释，以便检查我在客户端添加的超时代码。问题是，在超时发生后（因为从来没有发送回复），代码从开头开始，而不是我在TimeoutException catch（）中指定的发送标签

如果有人能帮我解决这两个问题中的任何一个，我将不胜感激

---

提前感谢您的时间

在循环之前创建套接字。目前你让它被垃圾收集

---

您关于套接字超时发生在

setSoTimeout（）

调用上的声明不正确。它发生在

receive（）。让我知道你对此的看法

客户：

import java.net.*;
import java.io.*; 
public class UDPClient {
    public static void main (String args[]){
        DatagramSocket aSocket = null;
        int input=-1;
        String operation=null;
        while(input!=0){
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            System.out.println("Select an option");
            System.out.println("1. Do a basic calculation");
            System.out.println("0. Exit ");
            try{
                input = Integer.parseInt(br.readLine());
                if(input>1 | input<0)throw new Exception("Error");
            }
              catch(Exception e){
                    System.out.println("Wrong selection...Try again \n");
                }
            if(input==1)
            {
                    System.out.println("Give operator symbol (+,-,*,/) ");
                    try{
                        String operator = br.readLine();
                        if(!(operator.matches("[*]|[+]|[/]|[-]")))throw new Exception("Error");
                        System.out.println("Give first number");
                        int first = Integer.parseInt(br.readLine());
                        System.out.println("Give second number");
                        int second = Integer.parseInt(br.readLine());
                        operation =  first+":"+operator+":"+second;
        send:
            try{
                aSocket = new DatagramSocket();
                byte [] m = operation.getBytes();
                InetAddress aHost = InetAddress.getByName(args[1]);
                int serverPort = 6789;
                DatagramPacket request = new DatagramPacket(m, m.length, aHost, serverPort);
                aSocket.send(request);
                aSocket.setSoTimeout(10000); // SocketTimeout happens here
                byte[]buffer = new byte[1000];
                DatagramPacket reply = new DatagramPacket(buffer, buffer.length);
                aSocket.receive(reply);
                System.out.println("Reply:" + new String(reply.getData()));

            }
            catch (SocketTimeoutException e) {
                System.out.println("Server reply timeout");
                break send;  //If Timeout happens, send request again
            }
            catch(SocketException e){
                System.out.println("Socket: " + e.getMessage());
            }
            catch(IOException e){
                    System.out.println("IO: " + e.getMessage());
            }
            finally {if (aSocket!=null) aSocket.close();}
            }
            catch(Exception e){
                System.out.println("Wrong input...Try again \n"); 
            }

        }//End of if
    }//end of while

    }
}

import java.net.*;
import java.io.*; 
public class UDPClient {
    public static void main (String args[]){
        DatagramSocket aSocket = null;
        int input=-1; //User Input from menu
        String operation=null; //keeps the calculation operation in String form
        int resends=0; //NACK counter
        while(input!=0){
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            System.out.println("Select an option");
            System.out.println("1. Do a basic calculation");
            System.out.println("0. Exit ");
            try{
                input = Integer.parseInt(br.readLine());
                if(input>1 | input<0)throw new Exception("Error");
            }
              catch(Exception e){
                    System.out.println("Wrong selection...Try again \n");
                }
            if(input==1)
            {
                    System.out.println("Give operator symbol (+,-,*,/) ");
                    try{
                        String operator = br.readLine();
                        if(!(operator.matches("[*]|[+]|[/]|[-]")))throw new Exception("Error");
                        System.out.println("Give first number");
                        int first = Integer.parseInt(br.readLine());
                        System.out.println("Give second number");
                        int second = Integer.parseInt(br.readLine());
                        operation =  first+":"+operator+":"+second;
                    }
                    catch(Exception e){
                        System.out.println("Wrong input...Try again \n"); 
                        System.out.println(e.getMessage());
                    }
           while(true){
                try{
                    if(resends==3){ // At 3 resends break loop
                        resends=0;
                        break;              
                    }
                    aSocket = new DatagramSocket();
                    byte [] m = operation.getBytes();
                    InetAddress aHost = InetAddress.getByName(args[1]);
                    int serverPort = 6789;
                    DatagramPacket request = new DatagramPacket(m, m.length, aHost, serverPort);
                    aSocket.send(request);
                    resends++;//counting times we send this message
                    aSocket.setSoTimeout(30000); // Setting timeout for socket (30 sec)
                    byte[]buffer = new byte[1000];
                    DatagramPacket reply = new DatagramPacket(buffer, buffer.length);
                    aSocket.receive(reply);
                    System.out.println("Reply:" + new String(reply.getData()));
                    if(reply!=null)break; // If you get a reply, break loop

                }
                catch (SocketTimeoutException e) {
                    System.out.println("Server reply timeout");         

                }
                catch(SocketException e){
                    System.out.println("Socket: " + e.getMessage());
                }
                catch(IOException e){
                        System.out.println("IO: " + e.getMessage());
                }
                finally {if (aSocket!=null) aSocket.close();}              
           }// end of send while loop

        }//End of if
            else if (input==0)
                System.out.println("Exiting UDP Client.....");

     }//end of while
  }//end of main

}//end of Class

在客户端，args[1]表示服务器的IP地址。如果您的服务器在本地主机上运行，您可以使用“127.0.0.1”。
很久没有看到有人在java代码中使用标签了！我也不推荐它。对于点
code
操作符处的正则表达式，匹配（“[*].[+].[/].[-]”
code
您可以使用
code
操作符。匹配（[*+/-]”
code
代替。很抱歉，刚刚获得了“到处注释”特权，了解如何使用标签。谢谢大家抽出时间，我会尝试你们建议的更正。谢谢你们抽出时间，但我无法理解你们的更正。你能说得更具体些吗？