package org.sw;

import java.util.Random;

/**

 * 得到指定位数的随机数

 * @author mengzw

 * @since 3.0 2014-2-28

 */

public class DemoRandom {

    /**

     * 获取随机数

     * @param length

     * @return

     */

    public String getCharAndNumr(int length)

    {

        String val = "";     

        Random random = new Random();

        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)) // 字符串

            {

                int choice = random.nextInt(2) % 2 == 0 ? 65 : 97; //取得大写字母还是小写字母

                val += (char) (choice + random.nextInt(26));

            }

            else if("num".equalsIgnoreCase(charOrNum)) // 数字

            {

                val += String.valueOf(random.nextInt(10));

            }

        }     

        return val;

    }   

    public static void main(String[] args) {

        DemoRandom dr = new DemoRandom();

        String random = dr.getCharAndNumr(13);

        System.out.println(random);

    }

}