客户端

1. 连接服务器Socket
2. 发送消息

package top.ltyzqhh.Net;

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

//客户端
public class TCPClientDemo01 {
    public static void main(String[] args) {
        Socket socket=null;
        OutputStream os =null;
        try {
             //1.要知道服务器地址
            InetAddress serverIP = InetAddress.getByName("127.0.0.1");
            //2.端口号
            int port =19999;
            //3,创建一个socket链接
             socket = new Socket(serverIP,port);
            //4.发送消息 IO流
            os = socket.getOutputStream();

            os.write("你好,欢迎学习狂神说java".getBytes());

        }
         catch (IOException e) {
            e.printStackTrace();
        }finally {
            if (os!=null) {
            try {
                os.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
                        }
            if (socket!=null) {
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

        }
    }
}

服务器

1. 建立服务的端口 ServerSocket
2. 等待用户的链接→accept
3. 接收用的消息

package top.ltyzqhh.Net;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;

//服务端
public class TCPServiceDemo01 {
    public static void main(String[] args) {
        ServerSocket serverSocket=null;
        Socket socket=null;
        InputStream is=null;
        ByteArrayOutputStream baos=null;
        try {
            //1.我得有一个地址
             serverSocket = new ServerSocket(19999);
            //2.等待客户端链接
             socket = serverSocket.accept();
            //3.读取客户端的消息
             is = socket.getInputStream();
            //4.管道流
             baos = new ByteArrayOutputStream();
            byte[] buffer = new byte[1024];
            int len;
            while((len=is.read(buffer))!=-1){
                baos.write(buffer,0,len);
            }
            System.out.println(baos.toString());

        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            //关闭资源
                if(baos!=null){
                    try {
                        baos.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                if (is!=null)
                {
                    try {
                        is.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }if (socket!=null)
                {
                    try {
                        socket.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }if (serverSocket!=null)
                {
                    try {
                        serverSocket.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }