网络编程（2）

UDP

发短信：不用连接，但需要知道对方的地址

发送消息

• 发送端

package Address;

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

public class UDPClient1 {

	public static void main(String[] args) throws Exception {
		
		/* 1.建立一个Socket */
		DatagramSocket socket = new DatagramSocket();
				
		/* 2.建个包 */
		String msg = "HELLO";
		InetAddress localhost = InetAddress.getByName("localhost");
		int port = 9090;
		
		DatagramPacket packet = new DatagramPacket(msg.getBytes(),
				msg.getBytes().length,localhost,port);
		
		/* 3.发送包 */
		socket.send(packet);
		
		/* 4.关闭流 */
		socket.close();
	}
}

• 接收端

package Address;

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

/* 还是要等待客户端的连接 */
public class UDPServer1 {

	public static void main(String[] args) throws Exception {
		/* 1.开发端口 */
		DatagramSocket socket = new DatagramSocket(9090);
		
		/* 2.接收数据包 */
		byte[] buffer = new byte[1024];
		DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);
		socket.receive(packet);//阻塞接收
		
		System.out.println(packet.getAddress().getHostAddress());
		System.out.println(new String(packet.getData(),0,packet.getLength()));
		
		/* 3.关闭连接 */
		socket.close();
	}
}

实现多线程通信

package chat;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;

public class TalkSend implements Runnable {

	DatagramSocket socket = null;
	BufferedReader reader = null;
	
	@SuppressWarnings("unused")
	private int fromPort;
	private String toIP;
	private int toPort;
	
	public TalkSend(int fromPort, String toIp, int toPort) {
		this.fromPort = fromPort;
		this.toIP = toIp;
		this.toPort = toPort;
		
		try {
			socket = new DatagramSocket(fromPort);
			reader = new BufferedReader(new InputStreamReader(System.in));
		}catch (Exception e) {
			e.printStackTrace();
		}
		
	}
	
	@Override
	public void run() {
		// TODO Auto-generated method stub
		
		
		while(true) {
			try {
				String data = reader.readLine();
				byte[] datas = data.getBytes();
				DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress(this.toIP,this.toPort));
				
				socket.send(packet);
				
				if(data.equals("bye")) {
					break;
				}
			}catch (Exception e) {
				e.printStackTrace();
			}
		
		}
		
		socket.close();
	
	}

}

package chat;

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

public class TalkReceive implements Runnable{

	DatagramSocket socket = null;
	
	@SuppressWarnings("unused")
	private int port;
	private String msgFrom;
	
	public TalkReceive(int port, String msgFrom) {
		this.port = port;
		this.msgFrom = msgFrom;
		
		try {
			socket = new DatagramSocket(6666);
		} catch (SocketException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}
	
	@Override
	public void run() {
		// TODO Auto-generated method stub
		
		while(true) {
			
			try {
				/* 准备接收包裹 */
				byte[] container = new byte[1024];
				
				DatagramPacket packet = new DatagramPacket(container,0,container.length);

				/* 阻塞式接收包裹 */
				socket.receive(packet);
				
				/* 断开连接 */
				byte[] data= packet.getData();
				String receiveData = new String(data,0,data.length);
				
				System.out.println(msgFrom+":"+receiveData);
				
				if(receiveData.equals("bye")) {
					break;
				}
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
		}
		socket.close();
	
	}

}

package chat;

public class TalkStudent {

	public static void main(String[] args) {
		
		/* 开启两个线程 */
		new Thread(new TalkSend(7777,"localhost",9999)).start();
		new Thread(new TalkReceive(8888,"老师")).start();
		
	}
}

package chat;

public class TalkTeacher {

	public static void main(String[] args) {
		new Thread(new TalkSend(5555,"localhost",8888)).start();
		new Thread(new TalkReceive(9999,"学生")).start();
	}
}

URL

• URL：统一资源定位符，定位互联网上的某一个资源
• 协议：//IP地址：端口号/项目名

package Address;

import java.net.MalformedURLException;
import java.net.URL;

public class URLTest1 {

	public static void main(String[] args) throws MalformedURLException {
		
		URL url = new URL("http://localhost:8080/helloworld/index.jsp?user");
		
		System.out.println(url.getProtocol());//协议
		System.out.println(url.getHost());//主机IP
		System.out.println(url.getPort());//端口
		System.out.println(url.getPath());//文件
		System.out.println(url.getFile());//全路径
		System.out.println(url.getQuery());//参数
		
	}
}