JAVA编程实现随机生成指定长度的密码功能【大小写和数字组合】

import java.util.Random;public class PassWordCreate {  /**   * 获得密码   * @param len 密码长度   * @return   */  public String createPassWord(int len){    int random = this.createRandomInt();    return this.createPassWord(random, len);  }  public String createPassWord(int random,int len){    Random rd = new Random(random);    final int maxNum = 62;    StringBuffer sb = new StringBuffer();    int rdGet;//取得随机数    char[] str = { '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', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };    int count=0;    while(count < len){      rdGet = Math.abs(rd.nextInt(maxNum));//生成的数最大为62-1      if (rdGet >= 0 && rdGet < str.length) {        sb.append(str[rdGet]);        count ++;      }    }    return sb.toString();  }  public int createRandomInt(){    //得到0.0到1.0之间的数字，并扩大100000倍    double temp = Math.random()*100000;    //如果数据等于100000，则减少1    if(temp>=100000){      temp = 99999;    }    int tempint = (int)Math.ceil(temp);    return tempint;  }  public static void main(String[] args){    PassWordCreate pwc = new PassWordCreate();    System.out.println(pwc.createPassWord(8));  }}