Utils.java

package com.talk.demo.util;

import java.util.Random;

public class Utils {

    public static String uuid() {
        //return UUID.randomUUID().toString().substring(0, 24);
        return myUUID();
      }

      public static String myUUID() {
        StringBuilder sb = new StringBuilder();
        int start = 48, end = 58;
        appendChar(sb, start, end);
        appendChar(sb, 65, 90);
        appendChar(sb, 97, 123);
        String charSet = sb.toString();
        StringBuilder sb1 = new StringBuilder();
        for (int i = 0; i < 24; i++) {
          int len = charSet.length();
          int pos = new Random().nextInt(len);
          sb1.append(charSet.charAt(pos));
        }
        return sb1.toString();
      }
      
      public static void appendChar(StringBuilder sb, int start, int end) {
          int i;
          for (i = start; i < end; i++) {
            sb.append((char) i);
          }
        }
}