Customize a simple JSP tag

Web Project, New Java class:

[Java] package leon. webtest. tags;
 
Import java. text. SimpleDateFormat;
Import java. util. Date;
 
Import javax. servlet. jsp. JspException;
Import javax. servlet. jsp. JspWriter;
Import javax. servlet. jsp. tagext. TagSupport;
 
 
Public class DateTime extends TagSupport {
 
Private static final long serialVersionUID = 1L;
 
Public int doStartTag () throws JspException {
Try {
JspWriter out = this. pageContext. getOut ();

SimpleDateFormat sdf = new SimpleDateFormat ("yyyy-MM-dd hh: mm: ss ");

Out. println ("<span> ");
Out. println (sdf. format (new Date ()));
Out. println ("</span> ");
 
} Catch (Exception e ){
Throw new JspException (e. getMessage ());
}
Return SKIP_BODY;
}
}

Package leon. webtest. tags;

Import java. text. SimpleDateFormat;
Import java. util. Date;

Import javax. servlet. jsp. JspException;
Import javax. servlet. jsp. JspWriter;
Import javax. servlet. jsp. tagext. TagSupport;

Public class DateTime extends TagSupport {

Private static final long serialVersionUID = 1L;

Public int doStartTag () throws JspException {
Try {
JspWriter out = this. pageContext. getOut ();

SimpleDateFormat sdf = new SimpleDateFormat ("yyyy-MM-dd hh: mm: ss ");

Out. println ("<span> ");
Out. println (sdf. format (new Date ()));
Out. println ("</span> ");

} Catch (Exception e ){
Throw new JspException (e. getMessage ());
}
Return SKIP_BODY;
}
}
New tld file: WEB-INF/tld/webtest-tags.tld

[Html] <? Xml version = "1.0" encoding = "UTF-8"?>
<Taglib xmlns = "http://java.sun.com/xml/ns/j2ee"
Xmlns: xsi = "http://www.w3.org/2001/XMLSchema-instance"
Xsi: schemalLocation = "http://java.sun.com/xml/ns/j2ee web-jsptaglibrary_2_0.xsd"
Version = "2.0">
 
<Description> A tag library exercising SimpleTag handlers. </description>
<Tlib-version> 1.0 </tlib-version>
<Short-name> Examples </short-name>
<Uri>/MyTags </uri>
<Description> JSP Self-define Tag Library. </description>
 
<Tag>
<Description> This is an date time tag </description>
<Name> datetime </name>
<Tag-class> leon. webtest. tags. DateTime </tag-class>
<Body-content> empty </body-content>
</Tag>
</Taglib>

<? Xml version = "1.0" encoding = "UTF-8"?>
<Taglib xmlns = "http://java.sun.com/xml/ns/j2ee"
Xmlns: xsi = "http://www.w3.org/2001/XMLSchema-instance"
Xsi: schemalLocation = "http://java.sun.com/xml/ns/j2ee web-jsptaglibrary_2_0.xsd"
Version = "2.0">

<Description> A tag library exercising SimpleTag handlers. </description>
<Tlib-version> 1.0 </tlib-version>
<Short-name> Examples </short-name>
<Uri>/MyTags </uri>
<Description> JSP Self-define Tag Library. </description>

<Tag>
<Description> This is an date time tag </description>
<Name> datetime </name>
<Tag-class> leon. webtest. tags. DateTime </tag-class>
<Body-content> empty </body-content>
</Tag>
</Taglib>
Configuration in web. xml:

[Html] <? Xml version = "1.0" encoding = "UTF-8"?>
<Web-app id = "WebApp_ID" version = "2.4"
Xmlns = "http://java.sun.com/xml/ns/j2ee"
Xmlns: xsi = "http://www.w3.org/2001/XMLSchema-instance"
Xsi: schemaLocation = "http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<Display-name> WebTest </display-name>

<Welcome-file-list>
<Welcome-file> index.html </welcome-file>
<Welcome-file> index. jsp </welcome-file>
</Welcome-file-list>

<Jsp-config>
<Taglib>
<Taglib-uri>/MyTags </taglib-uri>
<Taglib-location>/WEB-INF/tld/webtest-tag.tld
</Taglib-location>
</Taglib>
</Jsp-config>
</Web-app>

<? Xml version = "1.0" encoding = "UTF-8"?>
<Web-app id = "WebApp_ID" version = "2.4"
Xmlns = "http://java.sun.com/xml/ns/j2ee"
Xmlns: xsi = "http://www.w3.org/2001/XMLSchema-instance"
Xsi: schemaLocation = "http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
 
<Display-name> WebTest </display-name>
 
<Welcome-file-list>
<Welcome-file> index.html </welcome-file>
<Welcome-file> index. jsp </welcome-file>
</Welcome-file-list>
 
<Jsp-config>
<Taglib>
<Taglib-uri>/MyTags </taglib-uri>
<Taglib-location>/WEB-INF/tld/webtest-tag.tld
</Taglib-location>
</Taglib>
</Jsp-config>
</Web-app>
Use in JSP:

First, import:

<% @ Taglib uri = "/MyTags" prefix = "leon" %>

 

Use tags:

<Leon: datetime/>

 

Enhanced version: The time to be displayed is dynamic and will jump in seconds like a clock.