JAVA网络编程入门的两个demo(TCP+UDP)

TCP服务器端

package org.bruce.basic;

import java.io.DataInputStream;
import java.io.IOException;
import java.net.Socket;
import java.net.UnknownHostException;

public class TestClient {

	public static void main(String[] args) {
		Socket s = null;

		try {
			s = new Socket("127.0.0.1", 8888);
			DataInputStream dis = new DataInputStream(s.getInputStream());
			System.out.println(dis.readUTF());
			dis.close();
			s.close();
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

}

TCP客户端

package org.bruce.basic;

import java.io.DataOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

public class TestServer {
	public static void main(String[] args) {
		ServerSocket ss = null;
		
		try {
			ss = new ServerSocket(9999);
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		try {
			while(true) {
				Socket s = ss.accept();
				System.out.println("a client connect!");
				DataOutputStream dos = new DataOutputStream(s.getOutputStream());
				dos.writeUTF("IPAddress = " + s.getInetAddress() + "	Port = " + s.getPort());
				dos.close();
				s.close();		
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

UDP服务器端

package org.bruce.basic;

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

//UDP传输是一种无连接的数据传输方式，相较于TCP传输，它也是有它存在的道理的
public class UDPServer {
	public static void main(String[] args) {
		
		//以 "字节数组" 的形式开辟一块内存用于缓存接收到的UDP数据包
		byte[] buffer = new byte[1024];
		
		//虽然开辟的缓冲内存大小为1024字节，但也可以设置一个小于该值的缓存空间接收数据包
		DatagramPacket dp = new DatagramPacket(buffer, buffer.length);
		DatagramSocket ds = null;
		try {
			//监听在UDP 9999 端口
			ds = new DatagramSocket(9999);
		} catch (SocketException e) {
			e.printStackTrace();
		}
		
		while(true) {
			try {
				//receive() 方法是一个阻塞性方法！
				ds.receive(dp);
			} catch (IOException e) {
				e.printStackTrace();
			}
			//从下一行代码中可以学习到一种用字节数组构造字符串对象的方法
			System.out.println(new String(buffer, 0, dp.getLength()));
		}
	}

}

UDP客户端

package org.bruce.basic;

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

public class UDPClient {

	public static void main(String[] args) {
		//先将 "Hello!" 封装成一个字符串对象，在调用其 getBytes() 方法将其转换成字节数组
		//转换成字节数组是为了方便传输
		byte[] buffer = (new String("Hello!")).getBytes();
		DatagramPacket dp = null;
		try {
			//将要发送的数据、要发送到什么地址设置好并打成一个 DatagramPacket 包
			dp = new DatagramPacket(buffer, buffer.length, new InetSocketAddress("127.0.0.1", 9999));
		} catch (SocketException e) {
			e.printStackTrace();
		}
		
		DatagramSocket ds = null;
		try {
			//new 一个DatagramSocket对象（即打开一个UDP端口准备从此处发出数据包）
			ds = new DatagramSocket(9998);
			ds.send(dp);
			ds.close();
		} catch (SocketException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

}