publicstaticStringgetStringRandom(intlength) {
Stringval="";
Randomrandom=newRandom();
// 参数length，表示生成几位随机数for (inti=0; i<length; i++) {
StringcharOrNum=random.nextInt(2) %2==0?"char" : "num";
// 输出字母还是数字if ("char".equalsIgnoreCase(charOrNum)) {
// 输出是大写字母还是小写字母inttemp=random.nextInt(2) %2==0?65 : 97;
val+= (char) (random.nextInt(26) +temp);
        } elseif ("num".equalsIgnoreCase(charOrNum)) {
val+=String.valueOf(random.nextInt(10));
        }
    }
returnval;
}

publicstaticStringgetOnlyNumRandom(intlength) {
Stringval="";
Randomrandom=newRandom();
for (inti=0; i<length; i++) {
val+=String.valueOf(random.nextInt(10));
    }
returnval;
}