Udp协议
1.客户端（与服务器不需建立连接）
//1.建立socket
DatagramSocket datagramSocket = new DatagramSocket();
//2.建立一个包
String msg = "你好！";
InetAddress localhost = InetAddress.getByName("127.0.0.1");
int post = 9000;
//数据，数据起始，数据长度，数据发送地址
DatagramPacket packet = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,localhost,post);
//3.发送包
datagramSocket.send(packet);
//4.关闭流
datagramSocket.close();
2.服务端（等待接受客户数据）
//1.创建一个端口
DatagramSocket datagramSocket = new DatagramSocket(9000);
//2.接受数据包
byte[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);datagramSocket.receive(packet);System.out.println(packet.getAddress().getHostAddress());
System.out.println(new String(packet.getData(),0,packet.getLength()));
//3.关闭资源
datagramSocket.close();
3.Udp聊天
//Sender
DatagramSocket socket = new DatagramSocket(9999);BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));while (true){String data = reader.readLine();byte[] bytes = data.getBytes();DatagramPacket packet = new DatagramPacket(bytes, 0, bytes.length,new InetSocketAddress("localhost",9000));socket.send(packet);if(data.equals("Bye")){break;}
}
socket.close();
//Receiver
DatagramSocket socket = new DatagramSocket(9000);while (true){byte[] container = new byte[1024];DatagramPacket packet = new DatagramPacket(container, 0,container.length);socket.receive(packet);String receiveData = new String(packet.getData(),0, packet.getLength());System.out.println(receiveData);if (receiveData.equals("Bye")){break;}
}
4.Udp多线程在线聊天
//发送
public class TalkSender implements Runnable{DatagramSocket socket;BufferedReader reader;private int fromPort;private int toPort;private String toIP;public TalkSender(int fromPort, int toPort, String toIP) throws SocketException {this.fromPort = fromPort;this.toPort = toPort;this.toIP = toIP;socket = new DatagramSocket(fromPort);reader = new BufferedReader(new InputStreamReader(System.in));}@Overridepublic void run() {try {while (true){String data = reader.readLine();byte[] bytes = data.getBytes();DatagramPacket packet = new DatagramPacket(bytes, 0, bytes.length,new InetSocketAddress(toIP,toPort));socket.send(packet);if(data.equals("Bye")){break;}}} catch (IOException e) {e.printStackTrace();} finally {socket.close();}}
}
//接收
public class TalkReceive implements Runnable{DatagramSocket socket;private int port;public TalkReceive(int port) throws SocketException {this.port = port;socket = new DatagramSocket(port);}@Overridepublic void run() {while (true){try {byte[] container = new byte[1024];DatagramPacket packet = new DatagramPacket(container, 0,container.length);socket.receive(packet);String receiveData = new String(packet.getData(),0, packet.getLength());System.out.println(receiveData);if (receiveData.equals("Bye")){break;}} catch (IOException e) {throw new RuntimeException(e);}}socket.close();}
}
//学生
public class Student {public static void main(String[] args) throws SocketException {new Thread(new TalkSender(9000,9999, "localhost")).start();new Thread(new TalkReceive(8000)).start();}
}
//老师
public class Teacher {public static void main(String[] args) throws SocketException {new Thread(new TalkSender(9900,8000,"localhost")).start();new Thread(new TalkReceive(9999)).start();}
}
URL(统一资源定位符：定位资源的)
DNS 域名解析 www.baidu.com ==>xxx.x.x.x
$$
协议：//IP地址：端口号/项目名/资源
$$
下载网络资源
//下载网易云音乐
//1.下载地址对象
URL url = new URL("\n" +"https://m801.music.126.net/20240626104551/9e6149f5e794ca208ff3364e74f57c51/jdyyaac/obj/w5rDlsOJwrLDjj7CmsOj/20289466004/7191/9c89/dca3/a0d98a2848ee5258b94cbc01a6f889c8.m4a");//2.连接资源的httpHttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();//3.copy资源
InputStream is = urlConnection.getInputStream();
FileOutputStream fileOutputStream = new FileOutputStream("music.m4a");byte[] buffer = new byte[1024];
int len;
while ((len=is.read(buffer)) != -1){fileOutputStream.write(buffer,0,len);
}
//4.关闭连接
is.close();
fileOutputStream.close();
urlConnection.disconnect();
