随机生成数字&字母的字符串

随机生成数字&字母的字符串

import java.util.Random;
import java.util.UUID;

public class CodeUtile {
    //随机生成11为数字
    public static String couponCode(){
        int first = new Random().nextInt(9);
        int rnd = UUID.randomUUID().toString().hashCode();
        if(rnd < 0){
        rnd = -rnd;
    }
    return first+String.format("%010d", rnd);
}
    //根据传如的长度 随机生成数字&字母的字符串
    public static String random1(int l){//传入的字符串的长度
        StringBuilder builder = new StringBuilder(l);
        for(int i = 0; i < l; i++){
            int r = (int) (Math.random()*3);
            int rn1=(int)(48+Math.random()*10);
            int rn2=(int)(65+Math.random()*26);
            int rn3=(int)(97+Math.random()*26);
            switch(r){
                case 0:
                    builder.append((char)rn1);
                    break;
                case 1:
                    builder.append((char)rn2);
                    break;
                case 2:
                    builder.append((char)rn3);
                    break;
            }
        }
        return builder.toString();
    }
}