java-五位元驗證碼

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package com._520it_char_sequence;

import java.util.Random;
import java.util.UUID;
public class RandomCodeDemo {
public static void main(String[] args) {
//產生一個5位元的隨機數
String code = UUID.randomUUID().toString().substring(0,5);
System.out.println(code);
//產生一個5位元的隨機數
String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
str+=str.toLowerCase();
str+="0123456789";
System.out.println(str);
StringBuilder sb = new StringBuilder(5);
for (int i = 0; i < 5; i++) {
char ch = str.charAt(new Random().nextInt(str.length()));
sb.append(ch);
}
System.out.println(sb);
}
}

java-五位元驗證碼