Java：随机验证码

     @Test
    public void test1() {
        Collection<String> c = new ArrayList<>();
        char[] chars = new char[6];
        for (int i = 0; i < 10; i++) {
            for (int j = 0; j < chars.length; j++) {
               chars[j] = math();
            }
            String str = new String(chars);
            c.add(str);
        }
        Iterator<String> iterator = c.iterator();
        while (iterator.hasNext()) {
            String next = iterator.next();
            System.out.println("随机验证码：" + next);
        }
    }
    public char math() {
        Random random = new Random();
        int j = random.nextInt(26) + 97;
        int i = random.nextInt(10) + 48;
        int k = random.nextInt(26) + 65;
        char c1 = (char) j;
        char c2 = (char) i;
        char c3 = (char) k;
        char[] data = {c1, c2, c3};
        String str = new String(data);
        int x = random.nextInt(3);
        char y = str.charAt(x);
        return y;
    }