获取随机字符以及获取随机数

/**
 * 获取随机字符
 *
 * @param length
 * @return java.lang.String
 **/
public static String getStringRandom(int length) {
    String val = "";
    Random random = new Random();

    // 参数length，表示生成几位随机数
    for (int i = 0; i < length; i++) {

        String charOrNum = 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
            int temp = random.nextInt(2) % 2 == 0 ? 65 : 97;
            val += (char) (random.nextInt(26) + temp);
        } else if ("num".equalsIgnoreCase(charOrNum)) {
            val += String.valueOf(random.nextInt(10));
        }
    }
    return val;
}

/**
 * 获取三位随机数
 *
 * @return
 */
public static int getThreeRandomNumber(){
    Random random = new Random();
    return random.nextInt(900)+100;
}