java 模拟多个客户端与服务器建立UDP连接

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Client.java

import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.InetSocketAddress;public class Client implements Runnable {private String ip;private int port;private String message;public Client() {}public Client(String ip, int port, String message) {super();this.ip = ip;this.port = port;this.message = message;}public void run() {try {DatagramSocket client = new DatagramSocket();byte[] messageBytes = Util.hexStringToBytes(message);InetSocketAddress socketAddress = new InetSocketAddress(ip, port);DatagramPacket sendData = new DatagramPacket(messageBytes,messageBytes.length);DatagramPacket receiveData = new DatagramPacket(new byte[25], 25);sendData.setSocketAddress(socketAddress);System.out.println("send:" + message);client.send(sendData);client.receive(receiveData);byte[] receiveMessage = receiveData.getData();System.out.println("received:"+ Util.bytesToHexString(receiveMessage));client.close();} catch (Exception e) {e.printStackTrace();}}}

Util.java

public class Util {/** * Convert byte[] to hex string.这里我们可以将byte转换成int， * 然后利用Integer.toHexString(int)来转换成16进制字符串。 *  * @param src *            byte[] data * @return hex string */public static String bytesToHexString(byte[] src) {StringBuilder stringBuilder = new StringBuilder("");if (src == null || src.length <= 0) {return null;}for (int i = 0; i < src.length; i++) {int v = src[i] & 0xFF;String hv = Integer.toHexString(v);if (hv.length() < 2) {stringBuilder.append(0);}stringBuilder.append(hv);}return stringBuilder.toString().toUpperCase();}/** * Convert byte to hex string *  * @param src * @return */public static String byteToHexString(byte src) {StringBuilder stringBuilder = new StringBuilder("");int v = src & 0xFF;String hv = Integer.toHexString(v);if (hv.length() < 2) {stringBuilder.append(0);}stringBuilder.append(hv);return stringBuilder.toString().toUpperCase();}/** * Convert hex string to byte[] *  * @param hexString *            the hex string * @return byte[] */public static byte[] hexStringToBytes(String hexString) {if (hexString == null || hexString.equals("")) {return null;}hexString = hexString.toUpperCase();int length = hexString.length() / 2;char[] hexChars = hexString.toCharArray();byte[] d = new byte[length];for (int i = 0; i < length; i++) {int pos = i * 2;d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));}return d;}/** * Convert char to byte *  * @param c *            char * @return byte */private static byte charToByte(char c) {return (byte) "0123456789ABCDEF".indexOf(c);}/** * 获取校验码 *  * @param hexStr * @return */public static String getChecksum(String hexStr) {byte[] message = hexStringToBytes(hexStr);byte temp = message[0];for (int i = 1; i < message.length; i++) {temp = (byte) (temp ^ message[i]);}return byteToHexString(temp);}}

3.Main.java

public class Main {public static void main(String[] args) throws InterruptedException {String ip = "127.0.0.1";int port = 9999;String messageFlag = "7E";for (int i = 100; i < 999; i++) {String messageBody = "F55509000018710438" + i;String checksum = Util.getChecksum(messageBody);String message = messageFlag + messageBody + checksum + messageFlag;new Thread(new Client(ip, port, message)).start();}}}

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