JSP Tag Files: A Powerful Tool for Template Inheritance

For simple static JSP projects, JSP Tag Files offer an ingenious solution for template inheritance.

JSP 2.0 Tag Files

Create a JSP Tag File with the .tag extension in your WEB-INF/tags directory. For example, wrapper.tag:

  <dobody></dobody>

Usage in JSP Page

In your .jsp file, include the tag file and use it as a custom tag:

<wrapper>
    <h1 id="Welcome">Welcome</h1>
</wrapper>

Generic Page Template

For more complex templates, consider a genericpage.tag:

  
    <div>
<p><strong>Usage of Generic Page Template</strong></p>
<p>This tag allows for header and footer customization:</p>
<pre class="brush:php;toolbar:false">


<genericpage>
    <attribute name="header">
      <h1 id="Welcome">Welcome</h1>
    </attribute>
    <attribute name="footer">
      <p></p></attribute></genericpage>

Custom User Page Template

Extending the generic page template, you can create a userpage.tag:

<genericpage>
    <attribute name="header">
      <h1 id="Welcome-userName">Welcome ${userName}</h1>
    </attribute>
    <attribute name="footer">
      <p></p></attribute></genericpage>

Usage of User Page Template

This tag enables customized headers with user data:

<userpage username="${user.fullName}">
  <p>
    First Name: ${user.firstName} <br>
    Last Name: ${user.lastName} <br>
    Phone: ${user.phone}<br>
  </p>
</userpage>

Reusable UserDetails Fragment

To make reusable fragments, create userdetail.tag:

First Name: ${user.firstName} <br>
Last Name: ${user.lastName} <br>
Phone: ${user.phone}<br>

Refactored User Page Template

With this fragment, the user page template can be refactored:

<userpage username="${user.fullName}">
  <p>
    <userdetail user="${user}"></userdetail>
  </p>
</userpage>

Conclusion

JSP Tag Files provide immense flexibility, allowing for the creation of custom templates, reusable components, and complex layouts. They empower developers to refactor and customize markup efficiently, resulting in a clean and maintainable codebase.