利用Math.random()生成字符串随机码

/**
     * 生成字符串随机码
     * <p>Title: getRandomString</p>
     * <p>Description: </p>
     * @param length
     * @return
     */
    public static String getRandomString(int length){
         String str="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
         Random random=new Random();
         StringBuffer sb=new StringBuffer();
         for(int i=0;i<length;i++){
           int number=random.nextInt(62);
           sb.append(str.charAt(number));
         }
         return sb.toString();
     }