网络编程UDP/TCP（Java）

UDP通信，多发多收
客户端代码：

//客户端代码
package network;
import java.net.*;
import java.util.Scanner;

public class Client {
    public static void main(String[] args) throws Exception{

        //创建Client对象
        DatagramSocket socket = new DatagramSocket(); //括号内可以指定端口号，不指定则默认为随机端口
        //将要发送的字符串数据转换成字节流
        Scanner sc = new Scanner(System.in);
        while(true){
            String temp = sc.nextLine();
            byte[] bytes = temp.getBytes();

            if (temp.equals("exit")){
                System.out.println("-----EXIT SUCCESSFULLY!-----");
                break;
            }
            //创建packet对象，参数依次为：1.要发送的数据，2.发送数据的大小，3.Server的IP地址，4.Server端程序的端口。
            DatagramPacket packet = new DatagramPacket(bytes,bytes.length, InetAddress.getLocalHost(),6666);

            //发送packet
            socket.send(packet);
            System.out.println("Client had sent packet over!");
        }
        //释放资源
        socket.close();
    }
}

服务端代码：

//服务端代码
package network;

import java.net.DatagramPacket;
import java.net.DatagramSocket;


public class Server {
    public static void main(String[] args) throws Exception {
        //创建服务端对象
        DatagramSocket socket = new DatagramSocket(6666);
        System.out.println("-----Server had started-----");

        while(true){
            //创建数据包对象
            byte[] buffer = new byte[1024 * 64];
            DatagramPacket packet = new DatagramPacket(buffer, buffer.length);

            //等待接收数据
            socket.receive(packet);

            int len = packet.getLength();
            String rs = new String(buffer,0,len); //转换字节流数据为字符

            System.out.println(rs);
            System.out.println(packet.getAddress().getHostAddress());
            System.out.println(packet.getPort());
            System.out.println("----------------------------");
        }

    }
}

TCP通信
客户端代码

//客户端
package TCP_demo;

import java.io.DataOutputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.util.Scanner;

public class Client {
    public static void main(String[] args) throws Exception {
        //创建Socket对象，并同时请求与服务端程序进行连接
        Socket socket  = new Socket("127.0.0.1",8888);

        //从socket通信管道中得到一个字节输出流，用来发数据给服务端程序
        OutputStream os = socket.getOutputStream();

        //把低级的字节输出流包装成数据输出流
        DataOutputStream dos = new DataOutputStream(os);
        Scanner sc = new Scanner(System.in);
        while(true){
            //写入字符数据
            String temp = sc.nextLine();
            if (temp.equals("exit")){
                break;
            }
            dos.writeUTF(temp);
            dos.flush();
        }
        dos.close();

        //释放连接资源
        socket.close();
    }
}

服务端代码

//服务端代码
package TCP_demo;

import java.io.DataInputStream;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class Server {
    public static void main(String[] args) throws Exception{
        //创建Serversocket对象，同时为服务端注册端口
        ServerSocket serversocket = new ServerSocket(8888);
        System.out.println("-------服务端已启动-------");
        //调用accept方法，阻塞等待客户端的连接请求，返回socket通信管道对象
        Socket socket = serversocket.accept();

        //从socket通信管道中得到一个字节输入流
        InputStream is = socket.getInputStream();

        //将原始的字节输入流包装成数据输入流
        DataInputStream dis = new DataInputStream(is);

        while(true){
            //读取字符数据
            try{
                String rs = dis.readUTF();
                System.out.println(rs);
            }catch (Exception e){
                System.out.println(socket.getRemoteSocketAddress()+"离线了.");
                dis.close();
                socket.close();
                break;
            }

            //获取客户端的IP地址
            System.out.println(socket.getRemoteSocketAddress());
        }

    }
}