#IDEA 小技巧

  • cmd + shift + enter代码自动补全。
  • cmd + p参数提示。
  • psvm等价于public static void main(String[] args) {}。
  • sout等价于System.out.println();。
  • cmd + alt + t可以在代码块外面添加：
    1. if
    2. if / else
    3. while
    4. do / while
    5. for
    6. try / catch
  • alt + enter 在 new MyClass();后会自动填充为MyClass myclass = new MyClass();。
  • cmd + alt + shift + l格式化代码。

#UDP 发送端

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package xyz.onns.chat;

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

public class MySender implements Runnable {
    DatagramSocket socket = null;
    BufferedReader reader = null;
    private String toIP;
    private int fromPort;
    private int toPort;

    public MySender(String toIP, int fromPort, int toPort) {
        this.toIP = toIP;
        this.fromPort = fromPort;
        this.toPort = toPort;
        try {
            socket = new DatagramSocket(fromPort);
            reader = new BufferedReader(new InputStreamReader(System.in));
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        while (true) {
            try {
                String data = reader.readLine();
                byte[] buffer = data.getBytes();
                DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length, new InetSocketAddress(toIP, toPort));
                socket.send(packet);
                if (data.trim().equals("bye")) {
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

#UDP 接收端

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package xyz.onns.chat;

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

public class MyReceiver implements Runnable {
    DatagramSocket socket = null;
    private int port;
    private String from;

    public MyReceiver(int port, String from) {
        this.port = port;
        this.from = from;
        try {
            socket = new DatagramSocket(port);
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }


    @Override
    public void run() {
        while (true) {
            try {
                byte[] buffer = new byte[1024];
                DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
                socket.receive(packet);
                byte[] data = packet.getData();
                String message = new String(data, 0, data.length);
                System.out.println(from + " : " + message);
                if (message.trim().equals("bye")) {
                    break;
                }

            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

#测试类

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package xyz.onns.chat;

public class TalkStudent {
    public static void main(String[] args) {
        new Thread(new MySender("localhost",7777,9999)).start();
        new Thread(new MyReceiver(8888,"teacher")).start();
    }
}
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package xyz.onns.chat;

public class TalkTeacher {
    public static void main(String[] args) {
        new Thread(new MySender("localhost",5555,8888)).start();
        new Thread(new TalkReceiver(9999,"student")).start();
    }
}