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

/**
 * @author Lenovo
 * @date 2020/12/2
 */

public class Client{
    public void RunClient() throws IOException {
        //创建一个Socket对象
        Socket client = new Socket("localhost",9999);
        // 创建发送的线程类对象
        Send send = new Send(client);
        // 创建接收的线程类对象
        Receive receive = new Receive(client);
        new Thread(send).start();
        new Thread(receive).start();
    }
    public static void main(String[]args) throws IOException {
        new Client().RunClient();
    }
}

class Send implements  Runnable{// 实现发送功能
    // 从键盘获取数据
    private BufferedReader br;

    // 发送数据的数据流
    DataOutputStream dos ;

    private boolean flag = true;    //是否正常

    public Send(){
        br = new BufferedReader(new InputStreamReader(System.in));
    }

    public Send(Socket client){
        this(); //调用本类无参方法
        try{
            dos = new DataOutputStream(client.getOutputStream());
        } catch (IOException e) {
            e.printStackTrace();
            flag = false;
            CloseUtil.closeAll(dos,client);
        }
    }

    private String getMessage(){
        String str = "";
        try{
            str = br.readLine();
        } catch (IOException e) {
            e.printStackTrace();
            flag = false;
            CloseUtil.closeAll(br);
        }
        return  str;
    }

    private void send(String str){
        try{
            dos.writeUTF(str);
            dos.flush();
        } catch (IOException e) {
            e.printStackTrace();
            flag = false;
            CloseUtil.closeAll(dos);
        }
    }

    @Override
    public void run() {
        while(flag){
            //循环调用发送信息方法
            this.send(getMessage());

        }
    }
}

class  Receive implements Runnable{
    //用于接收数据的数据流
    private DataInputStream dis ;
    private boolean flag =true;

    public Receive(Socket client){
        try{
            dis  = new DataInputStream(client.getInputStream());
        } catch (IOException e) {
            e.printStackTrace();
            flag = false;
            CloseUtil.closeAll(dis,client);
        }
    }
    private  String getMessage(){
        String str ="";
        try{
            str = dis.readUTF();
        } catch (IOException e) {
            e.printStackTrace();
            flag = false;
            CloseUtil.closeAll(dis);
        }
        return str;
    }
    @Override
    public void run() {
        while(flag){
            System.out.println(this.getMessage());
        }
    }
}

1.2、关闭类

import java.io.Closeable;
import java.io.IOException;

/**
 * @author Lenovo
 * @date 2020/12/2
 */
public class CloseUtil {
    public  static void closeAll(Closeable... able){
        for(Closeable c:able){
            if(c!=null){
                try{
                    c.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

}

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * @author Lenovo
 * @date 2020/12/2
 */
public class Server {
    // 创建一个 ServerSocket类对象
    ServerSocket server;
    Socket socket;

    // 监听客户端是否有连接
    // 获取输入输出流接收数据
    DataInputStream dis ;
    DataOutputStream dos;

    public Server() throws IOException {
        server = new ServerSocket(9999);
    }

    public void RunServer() throws IOException {
        socket = server.accept();
        dis = new DataInputStream(socket.getInputStream());
        dos =new DataOutputStream(socket.getOutputStream());
        while(true) {
            String str = dis.readUTF();
            System.out.println("客户端发送的数据是" + str);

            dos.writeUTF("服务器端收到了" + str);
        }
        // 关闭所有流
        // CloseUtil.closeAll(dos,dis,socket);
    }
    public static void main(String[]args) throws IOException {
        new Server().RunServer();
    }
}

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

/**
 * @author Lenovo
 * @date 2020/12/2
 */

public class Client{
    public void RunClient() throws IOException {
        //创建一个Socket对象
        Socket client = new Socket("localhost",9999);
        // 创建发送的线程类对象
        Send send = new Send(client);
        // 创建接收的线程类对象
        Receive receive = new Receive(client);
        new Thread(send).start();
        new Thread(receive).start();
    }
}

class Send implements  Runnable{// 实现发送功能
    // 从键盘获取数据
    private BufferedReader br;

    // 发送数据的数据流
    DataOutputStream dos ;

    private boolean flag = true;    //是否正常

    public Send(){
        br = new BufferedReader(new InputStreamReader