Java生成验证码

                Random y=new Random();
		int s=y.nextInt(37);
		String a="s7q8r5s2b1g2d3s6a9f5c1v2f5h6j8g9p6h9f8c1";		
		System.out.println(a.substring(s, s+4));

基本思路：首先插入一段数字与字母的字符串；

              然后利用随机数生成随机数；

              然后用生成的随机数作为索引，截取该数的后面四位。

输出结果：　

　

第二种方法

基本思路

1、定义一个String[]zimu={"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"};

2、生成随机数作为索引

3、生成10以内的数字

4、输出。

String[]zimu={"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"};
	Random suoyin=new Random();
	Random shu=new Random();
	System.out.println(zimu[suoyin.nextInt(27)]+shu.nextInt(10)+zimu[suoyin.nextInt(27)]+shu.nextInt(10));

　　

输出结果