生成字母加数字字符串方法

/** * 获得随意长度数字加字母验证码字符串 * @param length 随意长度 * @return 字符串 */ public static String getCharacterAndNumber(int length){     String val = "";     Random random = new Random();      for (int i = 0; i < length; i++) {         String charOrNum = random.nextInt(2)%2==0?"char":"num";          if ("char".equalsIgnoreCase(charOrNum))          {            int choice =random.nextInt(2)%2==0?65:97;             val +=(char)(choice+random.nextInt(26));          } else if("num".equalsIgnoreCase(charOrNum)){          val += String.valueOf(random.nextInt(10));         }       }      return val;  }