JS代码如下：
/**
* @param
* @arrange (512.笔记) jb51.cc
* param flag 是否是任意长度
* param min 任意长度最小值
* param max 任意长度最大值
*/
function randomStr(flag,min,max) {
var str = "";
var index = "";
var range = min;
var arr = ['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'];
//min,max范围内随机的一个数
if(flag) {
range = Math.floor(Math.random() * (max - min + 1) + min);
}
for(var i = 0; i < range; i++) {
index = Math.round(Math.random() * (arr.length - 1));
str += arr[index];
}
return str;
}
// 来自：编程之家 jb51.cc（jb51.cc）