[网络协议]TCP/IP通信

TCP

三次握手，四次挥手

InetAddress可以查看本机ip

发送端：

InetAddress address = InetAddress.getByName("127.0.0.1");
int port = 9999;

Socket socket = new Socket(address, port);

OutputStream os = socket.getOutputStream();

os.write("测试数据".getBytes());


os.close();
socket.close();

接收端：

ServerSocket serverSocket = new ServerSocket(9999);

Socket accept = serverSocket.accept();

InputStream is = accept.getInputStream();

//管道
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
byte[] bytes = new byte[1024];
int len;
while ((len = is.read(bytes))!=-1){
   byteArrayOutputStream.write(bytes,0,len);
}
   System.out.println(byteArrayOutputStream);

UDP

发送端：

DatagramSocket datagramSocket = new DatagramSocket();

String msg = "你好啊";
InetAddress address = InetAddress.getByName("localhost");
int port = 6666;

DatagramPacket datagramPacket = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,address,port);

datagramSocket.send(datagramPacket);

datagramSocket.close();

接收端：

DatagramSocket datagramSocket = new DatagramSocket(6666);

byte[] bytes = new byte[1024];
 
DatagramPacket datagramPacket = new DatagramPacket(bytes,0,bytes.length);

datagramSocket.receive(datagramPacket);

System.out.println(datagramPacket.getAddress()+" : "+datagramPacket.getPort());
        String s = new String(datagramPacket.getData(), 0, datagramPacket.getLength());
        System.out.println(s);

datagramSocket.close();

UPD聊天

send

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.*;

public class Send implements Runnable {

    private int fromPort;
    private String toIP;
    private int toPort;

    DatagramSocket datagramSocket = null;
    BufferedReader reader = null;

    public Send(int fromPort, String toIP, int toPort) {
        this.fromPort = fromPort;
        this.toIP = toIP;
        this.toPort = toPort;

        try {
            datagramSocket = new DatagramSocket(fromPort);
            reader = new BufferedReader(new InputStreamReader(System.in));
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        try {
            while (true) {
                String s = reader.readLine();
                DatagramPacket datagramPacket = new DatagramPacket(
                        s.getBytes(), 0, s.getBytes().length,
                        new InetSocketAddress(this.toIP, this.toPort)
                );

                datagramSocket.send(datagramPacket);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                reader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            datagramSocket.close();
        }
    }
}

receive

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class Receive implements Runnable{

    DatagramSocket datagramSocket = null;

    private int port;
    private String name;

    public Receive(int port,String name) {
        this.port = port;
        this.name = name;

        try {
            datagramSocket = new DatagramSocket(port);
        } catch (SocketException e) {
            e.printStackTrace();
        }

    }

    @Override
    public void run() {
        try {

            while (true){
                byte[] bytes = new byte[1024];

                DatagramPacket datagramPacket = new DatagramPacket(bytes,0,bytes.length);

                datagramSocket.receive(datagramPacket);

                byte[] data = datagramPacket.getData();

                System.out.println(datagramPacket.getAddress()+" : "+datagramPacket.getPort()+" ---> "+
                        name+" : "+new String(data,0,datagramPacket.getLength()));
            }

        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            datagramSocket.close();
        }

    }
}

Student用户

public class Student {

    public static void main(String[] args) {
        new Thread(new Send(7777,"localhost",9999)).start();
        new Thread(new Receive(8888,"老师")).start();
    }
}

Teacher用户

public class Teacher {

    public static void main(String[] args) {
        new Thread(new Send(10001,"localhost",8888)).start();
        new Thread(new Receive(9999,"同学")).start();
    }
}