package lesson02;

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

/**
 * 客户端
 */
public class TcpClientDemo1 {

    public static void main(String[] args) {

        Socket socket = null;
        OutputStream os = null;

        try {
            //1、要知道服务器的地址 端口号
            InetAddress serverIP = InetAddress.getByName("127.0.0.1");
            int port = 9999;
            //2、创建一个 socket 连接
            socket = new Socket(serverIP, port);
            //3、发送消息 IO流
            os = socket.getOutputStream();
            os.write("你好，欢迎学习狂神学Java".getBytes());

        } catch (Exception 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();
                }
            }
        }
    }

}

服务端

1、建立服务的端口 ServerSocket

2、等待用户的连接 accept

3、接收用户的消息

package lesson02;

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 TcpServerDemo1 {

    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(9999);

            while (true){
                //2、等待客户端连接过来
                socket = serverSocket.accept();
                //3、读取客户端的消息
                is = socket.getInputStream();

                //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());
            }

            /*
            byte[] buffer = new byte[1024];
            int len;
            while ((len = is.read(buffer)) != -1){
                String msg = new String(buffer, 0, len);
                System.out.println(msg);
            }
            */

        } 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();
                }
            }
        }
    }

}