以下代码存在bug，请找出：package Y; import java.io.*; import java.net.*; import java.time.*; import java.util.*; public class Shiyan5Server { public static void main(String[] args) { ServerSocket server = null; Sy5ServerThread thread; Socket you = null; while(true) { try { server = new ServerSocket(2010); } catch (IOException e) { System.out.println("正在监听"); // TODO: handle exception } try { System.out.println("等待客户呼叫"); you = server.accept(); System.out.println("客户的地址"+you.getInetAddress()); } catch (Exception e) { // TODO: handle exception System.out.println("正在等待客户"); } if (you!=null) { new Sy5ServerThread(you).start(); } } } } class Sy5ServerThread extends Thread{ Socket socket; DataOutputStream out = null; DataInputStream in = null; String s = null; Sy5ServerThread(Socket t) { socket = t; try { out = new DataOutputStream(socket.getOutputStream()); in = new DataInputStream(socket.getInputStream()); } catch (IOException e) { e.printStackTrace(); // TODO: handle exception } } public void run() { while(true) { try { String S1 = "几点了?"; String S2 = "今天是几号?"; String S3 = "今天是星期几?"; String S4 = "再见"; String st = in.readUTF(); if (st.equals(S1)) { LocalTime time = LocalTime.now(); String Time = String.format("%tR", time); out.writeUTF(Time); } else if(st.equals(S2)) { LocalDate date = LocalDate.now(); String Time = String.format("%tm月%td日", date,date); out.writeUTF(Time); }else if (st.equals(S3)) { LocalDate week = LocalDate.now(); String Time = String.format("%tA", week); out.writeUTF(Time); }else if(st.equals(S4)) { System.out.println("结束服务"); break; } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }

在while(true)循环中，每次循环都会创建一个新的ServerSocket对象，这会导致已经被占用的端口无法再次使用，并抛出BindException异常。正确的做法是将ServerSocket的创建放在while循环外面，只创建一次即可。修改后的代码如下：

package Y;

import java.io.*;
import java.net.*;
import java.time.*;
import java.util.*;

public class Shiyan5Server {
    public static void main(String[] args) {
        ServerSocket server = null;
        Sy5ServerThread thread;
        Socket you = null;
        try {
            server = new ServerSocket(2010);
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        while (true) {
            try {
                System.out.println("等待客户呼叫");
                you = server.accept();
                System.out.println("客户的地址" + you.getInetAddress());
            } catch (Exception e) {
                // TODO: handle exception
                System.out.println("正在等待客户");
            }
            if (you != null) {
                new Sy5ServerThread(you).start();
            }
        }
    }
}

class Sy5ServerThread extends Thread {
    Socket socket;
    DataOutputStream out = null;
    DataInputStream in = null;
    String s = null;

    Sy5ServerThread(Socket t) {
        socket = t;
        try {
            out = new DataOutputStream(socket.getOutputStream());
            in = new DataInputStream(socket.getInputStream());
        } catch (IOException e) {
            e.printStackTrace();
            // TODO: handle exception
        }
    }

    public void run() {
        while (true) {
            try {
                String S1 = "几点了?";
                String S2 = "今天是几号?";
                String S3 = "今天是星期几?";
                String S4 = "再见";
                String st = in.readUTF();
                if (st.equals(S1)) {
                    LocalTime time = LocalTime.now();
                    String Time = String.format("%tR", time);
                    out.writeUTF(Time);
                } else if (st.equals(S2)) {
                    LocalDate date = LocalDate.now();
                    String Time = String.format("%tm月%td日", date, date);
                    out.writeUTF(Time);
                } else if (st.equals(S3)) {
                    LocalDate week = LocalDate.now();
                    String Time = String.format("%tA", week);
                    out.writeUTF(Time);
                } else if (st.equals(S4)) {
                    System.out.println("结束服务");
                    break;
                }
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }
    }
}