Java 生成随机字符的示例代码

import java.util.Random;

import java.util.UUID;

public class Dept {

     /**

      * 生成随机字符串 uuid

      */

     public static String getUUID() {

         return UUID.randomUUID().toString();

     }

     /**

      * 生成随机字符串 uuid 将"-"替换为""

      */

     public static String getUUNUM() {

         return UUID.randomUUID().toString().replace( "-" , "" );

     }

     /**

      * 生成指定位数的随机数

      * @param n 生成的随机数的位数

      */

     public static String getRandom(int n) {

         Random r = new Random();

         Long b = Math.abs(r.nextLong());

         return b.toString().substring(0, n);

     }

     public static void main(String[] args) {

         System.out.println(getUUNUM());

         System.out.println(getUUID());

         System.out.println(getRandom(6));

     }

}

//length用户要求产生字符串的长度

  public static String getRandomString( int length){

    String str= "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789" ;

    Random random= new Random();

    StringBuffer sb= new StringBuffer();

    for ( int i= 0 ;i<length;i++){

     int number=random.nextInt( 62 );

     sb.append(str.charAt(number));

    }

    return sb.toString();

  }

//可以指定字符串的某个位置是什么范围的值

  public static String getRandomString2( int length){

   Random random= new Random();

   StringBuffer sb= new StringBuffer();

   for ( int i= 0 ;i<length;i++){

     int number=random.nextInt( 3 );

     long result= 0 ;

     switch (number){

      case 0 :

        result=Math.round(Math.random()* 25 + 65 );

        sb.append(String.valueOf(( char )result));

        break ;

      case 1 :

        result=Math.round(Math.random()* 25 + 97 );

        sb.append(String.valueOf(( char )result));

        break ;

      case 2 :  

        sb.append(String.valueOf( new Random().nextInt( 10 )));

        break ;

     }

    }

    return sb.toString();

  }

String filename=RandomStringUtils.randomAlphanumeric( 10 );