java随机产生字符串

 今天在做一个注册模块，要求用到验证码。自己就试着写了一个。

/**

   * 产生随机字符串

   * */

private static Random randGen = null;

private static char[] numbersAndLetters = null;

private static Object initLock = new Object();

public static final String randomString(int length) {

         if (length < 1) {

             return null;

         }

         if (randGen == null) {

             synchronized (initLock) {

                 if (randGen == null) {

                     randGen = new Random();

                     numbersAndLetters = ("0123456789abcdefghijklmnopqrstuvwxyz" +

                     "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ").toCharArray();

                 }

             }

         }

         char [] randBuffer = new char[length];

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

             randBuffer[i] = numbersAndLetters[randGen.nextInt(71)];

         }

         return new String(randBuffer);

}

 

 

调用此方法randomString(int),int是字符串的长度，即可产生指定长度的随机字符串。