UDP

消息发送

发送端

​
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
​
//不需要连接服务器
public class UdpClientDemo01 {public static void main(String[] args) throws Exception {//1. 建立一个SocketDatagramSocket socket = new DatagramSocket();
​//2. 建个包String msg = "你好啊，服务器！";InetAddress localhost = InetAddress.getByName("localhost");int port = 9090;
​// 数据，数据的长度起始，要发送给谁DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);//3. 发送包socket.send(packet);
​//4. 关闭流socket.close();}
}

接收端

import java.net.DatagramPacket;
import java.net.DatagramSocket;
​
//还是要等待客户端的链接！
public class UdpServerDemo01 {public static void main(String[] args) throws Exception {//开放端口DatagramSocket socket = new DatagramSocket(9090);// 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()));
​//关闭连接socket.close();}
}

实现聊天

发送端

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketException;
​
public class UdpSenderDemo01 {public static void main(String[] args) throws Exception {DatagramSocket socket = new DatagramSocket(8888);
​// 准备数据：控制台读取 System.inBufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
​while (true) {String data = reader.readLine();byte[] datas = data.getBytes();DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress("localhost", 6666));
​socket.send(packet);if (data.equals("bye")) {break;}}
​socket.close();}
}

接受端

import javax.xml.stream.FactoryConfigurationError;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
​
public class UdpReceiveDemo01 {public static void main(String[] args) throws Exception {DatagramSocket socket = new DatagramSocket(6666);
​while (true) {// 准备接收包裹byte[] container = new byte[1024];DatagramPacket packet = new DatagramPacket(container, 0, container.length);socket.receive(packet); // 阻塞式接收包裹
​// 断开连接 byebyte[] data = packet.getData();String receiveData = new String(data, 0, packet.getLength());
​System.out.println(receiveData);
​if (receiveData.equals("bye")) {break;}}
​socket.close();}
}

在线咨询

在线咨询:两个人都可以是发送方，也都可以是接收方

TalkSend

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{private DatagramSocket socket = null;private BufferedReader reader = null;private int fromPort;private String toIP;private int toPort;
​public TalkSend(int formPort,String toIP,int toPort) {this.fromPort = formPort;this.toIP = toIP;this.toPort = toPort;
​try {socket = new DatagramSocket(fromPort);reader = new BufferedReader(new InputStreamReader(System.in));} catch (Exception e) {e.printStackTrace();}}
​@Overridepublic void run() {
​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();//reader.close();}
}
​

TalkReceive

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
​
public class TalkReceive implements Runnable{
​DatagramSocket socket = null;private int port;private String msgFrom;
​public TalkReceive(int port,String msgFrom){this.port = port;this.msgFrom = msgFrom;try {socket = new DatagramSocket(port);}catch (SocketException e){e.printStackTrace();}}@Overridepublic void run() {while (true){try {byte[] container = new byte[1024];DatagramPacket packet = new DatagramPacket(container,0,container.length);socket.receive(packet);//阻塞式接受包裹
​//断开连接byebyte[]data = packet.getData();String receiveData = new String(data,0,packet.getLength());System.out.println(msgFrom+""+receiveData);
​if (receiveData.equals("bye")){break;}
​}catch (IOException e){e.printStackTrace();}}socket.close();}
}

TalkStudent

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

TalkTeacher

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

统一资源定位符：定位资源，定位互联网上的某一个资源

URL下载

import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
​
public class UrlDown {public static void main(String[] args) throws Exception {// 1. 下载地址URL url = new URL("https://kkimgs.yisou.com/ims?kt=url&at=ori&key=aHR0cDovL3BpYzEuYXJrb28uY29tLzNBM0U3MTY5OTgzNDQ4NDI4MzU2M0JDNDdFOEE4RTY5L3BpY3R1cmUvb18xZmxzZnUxa2kxcW0xYm9oMXZhMjEzc3IxYWZhOC5qcGc=&sign=yx:tcu8a4v4pgux8UURHzXuKCIyTMo=&tv=0_0");
​// 2. 连接到这个资源 HTTPHttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
​InputStream inputStream = urlConnection.getInputStream();
​FileOutputStream fos = new FileOutputStream("d://SecurityFile.jpg");
​byte[] buffer = new byte[1024];int len;while ((len = inputStream.read(buffer)) != -1) {fos.write(buffer, 0, len); // 写出这个数据}
​fos.close();inputStream.close();urlConnection.disconnect(); // 断开连接}
}