Jakarta Project: RANDOM JSP Tag Library

Version 1.0

Table of Contents

Overview
Requirements
Configuration
Tag Summary
Tag Reference
Examples
Javadocs
Revision History

Overview

The Random tag library creates random strings and random numbers. You may specify a set of allowable characters as well as the length for randomly generated strings. You may specify a range of allowable integers or a random floating point number between zero and one for randomly generated numbers.

Requirements

This custom tag library requires no software other than a servlet container that supports the JavaServer Pages Specification, version 1.1.

Configuration

Follow these steps to configure your web application with this tag library:

To use the tags from this library in your JSP pages, add the following directive at the top of each page: 

<%@ taglib uri="random.jar" prefix="rand" %>

where "rand" is the tag name prefix you wish to use for tags from this library. You can change this value to any prefix you like. The prefix rand is used in the examples below.

Tag Summary
Random Tags
string
number

Tag Reference
 string Availability: version 1.0 
Set the properties of a variable length random string generator. A new random string will be created every time the jsp:getProperty tag is used to access the generator.
 
Tag Body empty
Script Variable Yes
Restrictions None
Attributes  
 
Name Required Runtime Expression Evaluation
 id  Yes  No
Script variable for use with the standard jsp:getProperty tag.
 length  No  No
The length of the random string. Defaults to a length of 8.
 map  No  No
Attribute name of a Bean or Script variable which is a Java HashMap object. The random string generated will be a new unique key for use as a key for the HashMap.
 charset  No  No
The set of characters to use when creating the random string. The following characters can be used as a
charset a-zA-Z0-9 ! @ # $ % ^ & * ( ) _ \- + = { } [ ] \\ | : ; \" ' < > , . ? /
The backslash, hyphen, and double quotes characters must be escaped with a \: like this \\, \-, and \". Lowercase alpha characters can be specified using a range like "a-z" or "f-r", the same can be done with uppercase letters A-Z and digits 0-9. To use the entire character set, set charset="all". Single characters must be separated by a space. Charset defaults to a value of a-zA-Z0-9.
Properties
 
Name Get Set
 random  Yes  No
Returns the variable length randomly generated string from the named generator.
Example 
<!-- Create a random string that is 8 characters long and that -->
<!-- uses a charset of all characters -->
<rand:string id="random1" charset="all"/>

<!-- Get the random string that was set up above, with a -->
<!--jsp:getProperty tag -->
<jsp:getProperty name="random1" property="random"/>

<!-- Create a random string that only uses uppercase letters -->
<rand:string id="random2" charset="A-Z"/>

<!-- Get the random string that was set up above, with a -->
<!--jsp:getProperty tag -->
<jsp:getProperty name="random2" property="random"/>

<!-- Create the same random string as above only make it -->
<!-- 15 character long -->
<rand:string id="random3" charset="A-Z" length="15"/>

<!-- Get the random string that was set up above, with a -->
<!--jsp:getProperty tag -->
<jsp:getProperty name="random3" property="random"/>

<!-- Create a random string that uses the following charset -->
<!-- A-Z ! @ # \\ \- + ? & $
<rand:string id="random4" charset="A-Z ! @ # \\ \- + ? & $"/>

<!-- Get the random string that was set up above, with a -->
<!--jsp:getProperty tag -->
<jsp:getProperty name="random4" property="random"/>

<!-- Create the default random string that uses a hashmap named -->
<!-- passkeys to make sure each randomly created string is unique. -->
<!-- This string defaults to a charset of a-zA-Z0-9. -->
<rand:string id="random5" map="passkeys"/>

<!-- Get the random string that was set up above, with a -->
<!--jsp:getProperty tag -->
<jsp:getProperty name="random5" property="random"/>
 number Availability: version 1.0 
Set the properties of a random number generator. A new random number will be generated each time the jsp:getProperty tag is used to access the generator .
 
Tag Body JSP
Script Variable Yes
Restrictions None
Attributes  
 
Name Required Runtime Expression Evaluation
 id  Yes  No
Script variable for use with the standard jsp:getProperty tag.
 range  No  No
This parameter determines the lower and upper bound from which to select the random number. If a range of 0-1 is selected, the tag will automatically create a float value between 0 and 1. The default range is the digits 0 to 100. Max size of the random number is limited by the size of the primitive data type of long.
Properties
 
Name Get Set
 random  Yes  No
Returns the randomly generated number as a Java Number object. In a JSP page the number is printed out as a string.
Example 
<!-- Create a default random number in the range 10000000-99999999. -->
<rand:number id="random1" range="10000000-99999999"/>

<!-- Get the random number, that was set up above,  using the -->
<!-- jsp:getProperty tag. -->
<jsp:getProperty name="random1" property="random"/>

<!-- Create a random number that is a float value by setting the -->
<!-- range to 0-1 -->
<rand:number id="random2" range="0-1"/>

<!-- Get the random number, that was set up above,  using the -->
<!-- jsp:getProperty tag. -->
<jsp:getProperty name="random2" property="random"/>

Examples

See random-examples.war for examples that use tags from this custom tag library.

Javadocs

Java programmers can view the java class documentation for this tag library as javadocs.

Revision History

Review the complete revision history of this tag library.