一、代码

    @Test
    public void test(){
        //包含数字、大小写字母，长度10-20位     
        String regular = "^(?=.*\\d)(?=.*[a-z])(?=.*[A-Z]).{10,20}$";
        String example1 = "1234567891";
        System.out.println(example1.matches(regular)); //false
        String example2 = "abcdefghjkl";
        System.out.println(example2.matches(regular)); //false
        String example3 = "ABCDEFGHJKL";
        System.out.println(example3.matches(regular)); //false
        String example4 = "1abAb1234564646";
        System.out.println(example4.matches(regular)); //true
    }

 二、测试

 三、其他正则匹配

常用正则表达式-事半功倍利器_1-31的正则表达式_好奇的菜鸟的博客-CSDN博客