因此，作为我的项目，我必须编写一个客户机类和一个简单的服务器类来回送客户机编写的消息。
出于某种原因，我要么得到i/o异常，要么得到一个套接字关闭的异常循环。
我真的很感激一些帮助，因为我与这个计划挣扎了两天，连续找不到任何解决办法。
我的服务器类：

import java.io.*;
import java.net.*;
import java.util.regex.Pattern;

public class SimpleServer {
    private ServerSocket ss = null;
    private BufferedReader in = null;
    private PrintWriter out = null;

public SimpleServer(String host, int port) {
    try {
    InetSocketAddress isa = new InetSocketAddress(host, port);
    ss = new ServerSocket();
    ss.bind(isa);
    } catch (IOException exc) {
        System.out.println("Error in constructor");
        System.exit(1);
    }
    System.out.println("Server started.");
    System.out.println("on port: " + ss.getLocalPort());
    System.out.println("bind address: " + ss.getInetAddress());
    serviceConnections();       
}//constructor

private void serviceConnections() {     
    boolean serverRunning = true;

    while(serverRunning) {
        try {
            Socket conn = ss.accept();
            System.out.println("Connection established!");
            serviceRequests(conn);              
        } catch (Exception exc) {
            exc.printStackTrace();
        }

        try { ss.close(); } catch (Exception exc) {}
    }       
}//serviceConnections

private void serviceRequests(Socket connection) throws IOException {
    try {
        in = new BufferedReader(new      InputStreamReader(connection.getInputStream()));
        out = new PrintWriter(connection.getOutputStream(), true);
        String line = in.readLine();            
        out.println(line);
    } catch (Exception exc) {
        exc.printStackTrace();
    } finally {
        try {
            in.close();
            out.close();
            connection.close();
            connection = null;
        } catch(Exception exc) {}
    }
}//serviceReq       

public static void main(String[] args) {

    String host = "localhost";
    int port = 2401;            
    new SimpleServer(host,port);        
}//main 
}//class

我的客户端类：

import java.net.*;
import java.io.*;

public class SimpleServerClient {

    private Socket sock = null;
    private PrintWriter out = null;
    private BufferedReader in = null;

public SimpleServerClient (String host, int port) {     
    try {
        sock = new Socket(host, port);
        out = new PrintWriter(sock.getOutputStream(),true);
        in = new BufferedReader(new InputStreamReader(sock.getInputStream()));
    //  System.out.println("Connected to the: " + sock.getInetAddress() );
        makeRequest("ECHO Howdy boy");      

    } catch (UnknownHostException e) {
        System.err.println("Unknown host: "+host);
        System.exit(2);
    } catch (IOException e) {
        System.err.println("I/O error for");
        System.exit(3);
    } catch (Exception exc) {
        exc.printStackTrace();
        System.exit(4);
    }
}//constructor

private void makeRequest(String req) throws IOException {
    System.out.println("Request: " + req);
    out.println(req);
    String resp = in.readLine();
    System.out.println(resp);
    disconnect();
}//method

public void disconnect() {
    try {
    out.close();
    sock.close();
    in.close();     
    } catch(IOException exc) {
        System.out.println("Error while closing");
        System.exit(5);
    }
}//method

public static void main(String[] args) {
    new SimpleServerClient("localhost", 2401);
}//main
}//class