写了一个获得随机数的类,大家看看!

[filippo1980]

import java.util.*;
import java.security.SecureRandom;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
/**
* 一个获得随机数的类
* <p>Copyright: 2004</p>
* @author Filippo Guan
* @version 1.1
*/

public class RandomStr
{
static String randomstr;
static boolean allchars = false;
//欠缺是8位字符串
static Integer length = new Integer(8);
static HashMap hmap;
static ArrayList lower = null;
static ArrayList upper = null;
static char[] single = null;
static int singlecount = 0;
static boolean singles = false;
static String algorithm = null;
static String provider = null;
static boolean secure = false;
static Random random = null;
static SecureRandom secrandom = null;

private static float getFloat()
{
if (random == null)
{
return secrandom.nextFloat();
}
else
{
return random.nextFloat();
}
}


public static void generateRandomObject() throws Exception
{
// check to see if the object is a SecureRandom object
if (secure)
{
try
{
// get an instance of a SecureRandom object
if (provider != null)
{

random = SecureRandom.getInstance(algorithm, provider);
}
else
{
random = SecureRandom.getInstance(algorithm);
}
}
catch (NoSuchAlgorithmException ne)
{
throw new Exception(ne.getMessage());
}
catch (NoSuchProviderException pe)
{
throw new Exception(pe.getMessage());
}
}
else
{
random = new Random();
}
}

/**
* generate the random string
*/
private static void generaterandom()
{
if (allchars)
{
for (int i = 0; i < length.intValue(); i++)
{
randomstr = randomstr + new Character((char)((int) 34 +((int)(getFloat() * 93)))).toString();
}
}
else if (singles)
{
// check if there are single chars to be included
if (upper.size() == 3)
{
// check for the number of ranges max 3 uppercase lowercase digits build the random string
for (int i = 0; i < length.intValue(); i++)
{
// you have four groups to choose a random number from, to make
// the choice a little more random select a number out of 100 get a random number even or odd
if (((int) (getFloat() * 100)) % 2 == 0)
{
// the number was even get another number even or odd
if (((int) (getFloat() * 100)) % 2 == 0)
{
// choose a random char from the single char group
randomstr = randomstr + randomSingle().toString();
}
else
{
// get a random char from the first range
randomstr = randomstr + randomChar((Character)lower.get(2),(Character)upper.get(2)).toString();
}
}
else
{
// the number was odd

if (((int) (getFloat() * 100)) % 2 == 0)
{
// choose a random char from the second range
randomstr = randomstr + randomChar((Character)lower.get(1),(Character)upper.get(1)).toString();
}
else
{
// choose a random char from the third range
randomstr = randomstr + randomChar((Character)lower.get(0),(Character)upper.get(0)).toString();
}
}
}
}
else if (upper.size() == 2)
{
// single chars are to be included choose a random char from
// two different ranges build the random char from single chars and two ranges
for (int i = 0; i < length.intValue(); i++)
{
// select the single chars or a range to get each random charfrom

if (((int)(getFloat() * 100)) % 2 == 0)
{
// get random char from the single chars
randomstr = randomstr + randomSingle().toString();
}
else if (((int) (getFloat() * 100)) % 2 == 0)
{
// get the random char from the first range
randomstr = randomstr + randomChar((Character)lower.get(1),(Character)upper.get(1)).toString();
}
else
{
// get the random char from the second range
randomstr = randomstr + randomChar((Character)lower.get(0),(Character)upper.get(0)).toString();
}
}
}
else if (upper.size() == 1)
{
// build the random string from single chars and one range
for (int i = 0; i < length.intValue(); i++)
{
if (((int) getFloat() * 100) % 2 == 0)
{
// get a random single char
randomstr = randomstr + randomSingle().toString();
}
else
{
// get a random char from the range
randomstr = randomstr + randomChar((Character)lower.get(0),(Character)upper.get(0)).toString();
}
}
}
else
{
// build the rand string from single chars
for (int i = 0; i < length.intValue(); i++)
{
randomstr = randomstr + randomSingle().toString();
}
}
}
else
{
// no single chars are to be included in the random string
if (upper.size() == 3)
{
// build random strng from three ranges
for (int i = 0; i < length.intValue(); i++)
{
if (((int) (getFloat() * 100)) % 2 == 0)
{
// get random char from first range
randomstr = randomstr + randomChar((Character)lower.get(2),(Character)upper.get(2)).toString();
}
else if (((int) (getFloat() * 100)) % 2 == 0)
{
// get random char form second range
randomstr = randomstr + randomChar((Character)lower.get(1),(Character)upper.get(1)).toString();
}
else
{
// get random char from third range
randomstr = randomstr + randomChar((Character)lower.get(0),(Character)upper.get(0)).toString();
}
}
}
else if (upper.size() == 2)
{
// build random string from two ranges
for (int i = 0; i < length.intValue(); i++)
{
if (((int) (getFloat() * 100)) % 2 == 0)
{
// get random char from first range
randomstr = randomstr + randomChar((Character)lower.get(1),(Character)upper.get(1)).toString();
}
else
{
// get random char from second range
randomstr = randomstr + randomChar((Character)lower.get(0),(Character)upper.get(0)).toString();
}
}
}
else
{
// build random string
for (int i = 0; i < length.intValue(); i++)
{
// get random char from only range
randomstr = randomstr + randomChar((Character)lower.get(0),(Character)upper.get(0)).toString();
}
}
}
}

[filippo1980]

/**
* generate a random char from the single char list
*
* @returns - a randomly selscted character from the single char list
*
*/
private static Character randomSingle()
{
return (new Character(single[(int)((getFloat() * singlecount) - 1)]));
}

/**
* generate a random character
*
* @param lower lower bound from which to get a random char
* @param upper upper bound from which to get a random char
*
* @returns - a randomly generated character
*
*/
private static Character randomChar(Character lower, Character upper)
{
int tempval;
char low = lower.charValue();
char up = upper.charValue();

// get a random number in the range lowlow - lowup
tempval = (int)((int)low + (getFloat() * ((int)(up - low))));

// return the random char
return (new Character((char) tempval));
}

/**
* get the randomly created string for use with the
* <jsp:getProperty name=<i>"id"</i> property="randomstr"/>
*
* @return - randomly created string
*
*/
public static String getRandom()
{
randomstr = new String();
generaterandom(); // generate the first random string

if (hmap != null)
{

while (hmap.containsKey(randomstr))
{
// random string has already been created generate a different one
generaterandom();
}

hmap.put(randomstr, null); // add the new random string
}

return randomstr;
}

/**
* set the ranges from which to choose the characters for the random string
*
* @param low set of lower ranges
* @param up set of upper ranges
*
*/
public static void setRanges(ArrayList low, ArrayList up)
{
lower = low;
upper = up;
}


/**
* set the hashmap that is used to check the uniqueness of random strings
*
* @param map hashmap whose keys are used to insure uniqueness of random strgs
*
*/
public static void setHmap(HashMap map)
{
hmap = map;
}

/**
* set the length of the random string
*
* @param value length of the random string
*
*/
public static void setLength(String value)
{
length = new Integer(value);
}

/**
* set the algorithm name
*
* @param value name of the algorithm to use for a SecureRandom object
*
*/
public static void setAlgorithm(String value)
{
algorithm = value;
secure = true; // a SecureRandom object is to be used
}

/**
* set the provider name
*
* @param value name of the package to check for the algorithm
*
*/
public static void setProvider(String value)
{
provider = value;
}

/**
* set the allchars flag
*
* @param value boolean value of the allchars flag
*
*/
public static void setAllchars(boolean value)
{
allchars = value;
}

/**
* set the array of single chars to choose from for this random string and the
* number of chars in the array
*
* @param chars the array of single chars
* @param value the number of single chars
*
*/
public static void setSingle(char[] chars, int value)
{
single = chars; // set the array of chars
singlecount = value; // set the number of chars in array single
singles = true; // set flag that single chars are in use
}

public static void setCharset(String value)
{
// values tells the method whether or not to check for single chars
boolean more = true;

// create the arraylists to hold the upper and lower bounds for the char
// ranges
lower = new ArrayList(3);
upper = new ArrayList(3);

// user has chosen to use all possible characters in the random string
if (value.compareTo("all") == 0)
{
allchars = true; // set allchars flag
// all chars are to be used so there are no single chars to sort
// through
more = false;
}
else if ((value.charAt(1) == '-') && (value.charAt(0) != '\\'))
{
// run through the ranges at most 3
while (more && (value.charAt(1) == '-'))
{
// check to make sure that the dash is not the single char
if (value.charAt(0) == '\\')
{
break;
}
else
{
// add upper and lower ranges to there list
lower.add(new Character(value.charAt(0)));
upper.add(new Character(value.charAt(2)));
}

// check to see if there is more to the charset
if (value.length() <= 3)
{
more = false;
}
else
{
// create a new string so that the next range if there is one
// starts it
value = value.substring(3);
}
}
}

// if more = false there are no single chars in the charset
if (more)
{
single = new char[30]; // create single

// create a set of tokens from the string of single chars
StringTokenizer tokens = new StringTokenizer(value);

while (tokens.hasMoreTokens())
{
// get the next token from the string
String token = tokens.nextToken();

if (token.length() > 1)
{
// char is a - add it to the list
single[singlecount++] = '-';
}

// add the current char to the list
single[singlecount++] = token.charAt(0);
}
}
if ((lower == null) && (single == null))
setCharset("a-zA-Z0-9");
}
}

[filippo1980]

关于使用:可以获得0-9 a-z A-Z

RandomStr.setCharset("0-9");
RandomStr.setLength("8");
RandomStr.generateRandomObject();
随机数(字符型) = RandomStr.getRandom();

欢迎大家多提建议和意见!

[Minsc79]

不错哦，只得学习

[talent_marquis]

正在研究如何一次取得不定数目个随机数中，一颗星星楼主能给我点提示不？

[aqua_w]

谢谢

[GaryZhu]

up

[xingwensh]

支持楼主，学习！

[lbl512]

看看，研究一下！

[filippo1980]

嘿嘿，自己想想吧！
setLength("i");

[caiyanying732]

学习

[txon]

顶，学习！

[hxg8690]

不错

[filippo1980]

up

[redcard]

up

[filippo1980]

自己顶一下！

[lostyq]

帮你顶一下

[zhaoweiping]

haha.....
good good study
day day up

wo yao xiang luo zhu xue java!!!

[filippo1980]

共同努力，共同学习！