一、什么是socket编程

socket编程，是在不同的进程间进行网络通讯的一种协议，在socket编程中基于TCP、UDP等协议做的一层封装，是一套系统所提供的的用于进行网络通信的编程接口。

二、 java实现socket代码

客户端java代码：

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.Socket;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.Scanner;

public class TcpSocketClient {

    /**
     * 客户端程序
     */
    public void client() throws IOException {
        Scanner scanner = new Scanner(System.in);
        System.out.println("等待连接服务端！");
        Socket socket = new Socket("127.0.0.1", 2111);
        System.out.println("连接服务端成功！");
        while (true) {
            // 给服务端发信息
            System.out.print("请输入：");
            String s = scanner.next();
            if ("out".equals(s)) {
                break;
            }
            OutputStream outputStream = socket.getOutputStream();
            outputStream.write(s.getBytes(StandardCharsets.UTF_8));
            byte[] bytes = new byte[1024];

            // 读一下服务端发来的信息
            InputStream inputStream = socket.getInputStream();
            int read = inputStream.read(bytes);
            System.out.println("服务端：" + new String(bytes, 0, read, Charset.defaultCharset()));
        }
    }

    public static void main(String[] args) throws IOException {
        TcpSocketClient tcpSocketServer = new TcpSocketClient();
        tcpSocketServer.client();
    }
}

服务端java代码：

import java.io.IOException;
import java.io.InputStream;
import java.ServerSocket;
import java.Socket;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.Scanner;

public class TcpSocketServer {

    /**
     * 服务端程序
     */
    public void server() throws IOException {

        Scanner scanner = new Scanner(System.in);

        // 服务端监听 1111 端口
        ServerSocket serverSocket = new ServerSocket(1111);
        System.out.println("等待连接");
        Socket client = serverSocket.accept();
        System.out.println("连接成功！");
        while (true) {
            // 获取客户端输入流
            InputStream inputStream = client.getInputStream();
            byte[] bytes = new byte[1024];
            int read = inputStream.read(bytes);
            // 客户端发来的消息
            System.out.println("客户端：" + new String(bytes, 0, read, Charset.defaultCharset()));

            // 给客户端发端消息
            System.out.print("请输入：");
            String nextLine = scanner.next();
            if ("out".equals(nextLine)) {
                break;
            }
            client.getOutputStream().write(nextLine.getBytes(StandardCharsets.UTF_8));
        }
    }
    public static void main(String[] args) throws IOException {
        TcpSocketServer tcpSocketServer = new TcpSocketServer();
        tcpSocketServer.server();;
    }
}