java的TCP和UDP编程

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

public class MyClient {

    public static void main(String[] args) throws Exception{
        
        Socket socket = null;
        BufferedReader in = null;
        PrintWriter out = null;
        
        BufferedReader input = null;
        // 请求指定ip和端口号的服务器
        socket = new Socket("127.0.0.1",3333);
        
        while(true){

            in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            
            out = new PrintWriter(socket.getOutputStream(), true);
            // 接收控制台的输入
            input = new BufferedReader(new InputStreamReader(System.in));
            // out.println("this is client info!");
            String info = input.readLine();
            
            out.println(info);
            
            String str = in.readLine();
            
            System.out.println("客户端显示--》服务器的信息：" + str);
        }
        //in.close();
        //out.close();
    }

}

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class MyServices {

    public static void main(String[] args) throws Exception{
        ServerSocket ss = null;
        Socket socket = null;
        BufferedReader in = null;
        PrintWriter out = null;
        BufferedReader input = null;
        
        // 监听3333端口
        ss = new ServerSocket(3333);
        // 等待接收客户端的请求
        socket = ss.accept();
        while(true){
            // 获取连接对象的输入流
            in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            // 获取客户端的输入信息
            String str = in.readLine();
            
            input = new BufferedReader(new InputStreamReader(System.in));
            
            System.out.println("服务器显示-->客户端输入数据：" + str);
            
            out = new PrintWriter(socket.getOutputStream(),true);
            // 将数据输出到客户端
            // out.println("hehe");
            String info = input.readLine();
            
            out.println(info);
        }
//        in.close();
//        out.flush();
//        out.close();
    }

}

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

public class UDPClient {

    public static void main(String[] args) throws Exception {
        
        DatagramSocket ds = null;
        DatagramPacket dp = null;
        byte[] buf = new byte[1024];
        
        ds = new DatagramSocket(3333);
        dp = new DatagramPacket(buf, 1024);
        
        // 接收数据，放入数据报
        ds.receive(dp);
        // 从数据报中取出数据
        String info = new String(dp.getData(),0, dp.getLength());
        System.out.println("接收到的信息是：" + info);
    }

}

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

public class UDPServer {

    public static void main(String[] args) throws Exception {
        DatagramSocket ds = null;
        DatagramPacket dp = null;
        
        // 构建发送对象
        ds = new DatagramSocket();
        // 将数据打包-->打成数据报
        String info = "hello world!";
        
        dp = new DatagramPacket(info.getBytes(), info.length(), InetAddress.getByName("localhost"),3333);
        
        // 发出数据报
        ds.send(dp);
        
    }

}