A custom tag: empty with attributes
///
<!-- this must be added to the web application's web.xml -->
<taglib>
<taglib-uri>/java2s</taglib-uri>
<taglib-location>/WEB-INF/java2s.tld</taglib-location>
</taglib>
// create File:java2s.tld in the /WEB-INF/
<!DOCTYPE taglib
PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN"
"http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd">
<!-- a tab library descriptor -->
<taglib xmlns="http://java.sun.com/JSP/TagLibraryDescriptor">
<tlib-version>1.0</tlib-version>
<jsp-version>1.2</jsp-version>
<short-name>Java2s Simple Tags</short-name>
<!-- this tag lists random numbers; the HTML is hard-coded within
the tag handler
-->
<tag>
<name>emptyTagWithAttrs</name>
<tag-class>com.java2s.EmptyTagWithAttrs</tag-class>
<body-content>empty</body-content>
<attribute>
<name>howMany</name>
</attribute>
</tag>
</taglib>
//compile the following code into WEB-INF\classes\com\java2s
package com.java2s;
import java.io.IOException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.TagSupport;
/* This tag handler generates the random numbers. The "howMany" attribute
specifies how many numbers to generate and display.
*/
public class EmptyTagWithAttrs extends TagSupport
{
// Code to implement the "howMany" attribute
private int howMany;
public int getHowMany()
{
return howMany;
}
public void setHowMany(int i)
{
howMany = i;
}
public int doStartTag() throws JspException
{
try
{
JspWriter out = pageContext.getOut();
for ( int i=0; i<this.howMany; i++ )
{
int nextNumber = (int) (Math.random() * 10);
out.println("<li>" + nextNumber + "</li>");
} // end of for ()
}
catch (IOException e)
{
System.out.println("Error in EmptyTagWithAttrs.doStartTag()");
e.printStackTrace();
throw new JspException(e); // throw the error to the error page (if set)
} // end of try-catch
return SKIP_BODY;
}
}
// start comcat and load the following jsp page in browser
<%@ taglib uri="/java2s" prefix="java2s" %>
<html>
<head>
<title>A custom tag: empty with attributes</title>
</head>
<body>
This page uses a custom tag that has no body content, but takes
an attribute called "howMany" that specifies how many random
numbers to generate. Here is its output:
<ul>
<java2:emptyTagWithAttrs howMany="5" />
</ul>
</body>
</html>
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