Java_随机生成4位验证码

import java.util.*;//导入java.util包下的类

public class JavaDemo10
{
	public static void main(String args[])
	{
		String str = "0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";
		String str2[] = str.split(",");//将字符串以,分割
		int sum = 0;//计数器
		for (int i=0; i<str2.length; ++i)
		{
			++sum;
			if (0 == sum % 10)
			{
				System.out.println("");//没十个数据换行
			}
			System.out.print(str2[i] + " ");
		}
		System.out.println("");
		Random rand = new Random();//创建Random类的对象rand
		int index = 0;
		String randStr = "";//创建内容为空字符串对象randStr
		Scanner scan = new Scanner(System.in);//创建Scanner类的对象
		while (!scan.next().equals("#"))//判断从键盘输入的是否是字符#
		{
			randStr = "";//清空字符串对象randStr中的值
			for (int i=0; i<4; ++i)
			{
				index = rand.nextInt(str2.length-1);//在0到str2.length-1生成一个伪随机数赋值给index
				randStr += str2[index];//将对应索引的数组与randStr的变量值相连接
			}
			System.out.println("验证码：" + randStr);//输出所求的验证码的值
		}
	}
	/*
	 *0 1 2 3 4 5 6 7 8
	 *9 a b c d e f g h i
	 *j k l m n o p q r s
	 *t u v w x y z A B C
	 *D E F G H I J K L M
	 *N O P Q R S T U V W
	 *X Y Z
	 *a
	 *验证码：u8rg
	 *#
	 *
	 * */
}