获取随机数(可用于生成验证码)
public static String getRandomChar() {
String base = "qwertyuiopasdfghjklzxcvbnmQWERTYUIOPLKJHGFDSAZXCVBNM1234567890";
Random random = new Random();
char ch = base.charAt(Math.abs(random.nextInt()) % base.length());
return ch + "";
}