基于Java随机生成手机短信验证码的实例代码

/**   * 产生4位随机数(0000-9999)

    *

    * @return 4位随机数

    */

   public static string getfourrandom() {

     return stringutils.leftpad( new random().nextint( 10000 ) + "" , 4 , "0" );

   }

/**

    * 创建指定数量的随机字符串

    * @param numberflag 是否是数字

    * @param length

    * @return

    */

   public static string createrandom( boolean numberflag, int length){

     string retstr = "" ;

     string strtable = numberflag ? "1234567890" : "1234567890abcdefghijkmnpqrstuvwxyz" ;

     int len = strtable.length();

     boolean bdone = true ;

     do {

       retstr = "" ;

       int count = 0 ;

       for ( int i = 0 ; i < length; i++) {

         double dblr = math.random() * len;

         int intr = ( int ) math.floor(dblr);

         char c = strtable.charat(intr);

         if (( '0' <= c) && (c <= '9' )) {

           count++;

         }

         retstr += strtable.charat(intr);

       }

       if (count >= 2 ) {

         bdone = false ;

       }

     } while (bdone);

     return retstr;

   }