优化下面代码package Y; import java.io.*; import java.net.*; import java.util.*; public class Shiyan5Client { public static void main(String[] args) { Scanner sc = new Scanner(System.in); Socket mysocket = null; DataInputStream in = null; DataOutputStream out = null; Thread timeData; TellTime time = null; try { mysocket = new Socket(); time = new TellTime(); timeData = new Thread(time); System.out.println("输入服务器IP:"); String IP = sc.nextLine(); System.out.println("输入端口号:"); int port = sc.nextInt(); if (mysocket.isConnected()) {} else { InetAddress address = InetAddress.getByName(IP); InetSocketAddress socketAddress = new InetSocketAddress(IP, port); mysocket.connect(socketAddress); in = new DataInputStream(mysocket.getInputStream()); out = new DataOutputStream(mysocket.getOutputStream()); time.setDataInputStream(in); timeData.start(); } } catch (Exception e) { System.out.println("服务器已断开:"+e); // TODO: handle exception } System.out.println("请输入服务:"); while (sc.hasNext()) { try { String service = sc.next(); out.writeUTF(service); } catch (Exception e) { // TODO: handle exception } } } }

下面是优化后的代码：

package Y;

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

public class Shiyan5Client {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        Socket mysocket = null;
        DataInputStream in = null;
        DataOutputStream out = null;
        Thread timeData;
        TellTime time = null;

        try {
            System.out.println("输入服务器IP:");
            String IP = sc.nextLine();
            System.out.println("输入端口号:");
            int port = sc.nextInt();
            sc.nextLine(); // 读取换行符

            mysocket = new Socket(IP, port);
            in = new DataInputStream(mysocket.getInputStream());
            out = new DataOutputStream(mysocket.getOutputStream());

            time = new TellTime();
            time.setDataInputStream(in);
            timeData = new Thread(time);
            timeData.start();
        } catch (Exception e) {
            System.out.println("连接服务器失败：" + e);
            return;
        }

        System.out.println("请输入服务:");
        while (sc.hasNext()) {
            try {
                String service = sc.next();
                out.writeUTF(service);
            } catch (Exception e) {
                System.out.println("发送数据失败：" + e);
                return;
            }
        }

        try {
            mysocket.close();
        } catch (IOException e) {
            System.out.println("关闭套接字失败：" + e);
        }
    }
}

主要改进如下：

1. 将连接服务器的代码放在 try 块中，如果连接失败直接返回，避免出现空指针异常。
2. 读取完端口号后需要调用 `sc.nextLine()` 读取掉换行符，否则下一个读取字符串操作会读到空字符串。
3. 当发送数据失败时应该直接返回，避免继续执行程序出现异常。
4. 在程序结束时应该关闭套接字。