How to Customize Servlet Mapping for Efficient Static Content Serving?

Customizing Servlet Mapping for Static Content Serving

Background:

When deploying web applications on different containers, variations in default servlets that handle static content handling can arise. This can lead to conflicts with the desired URL structure.

Servlet Requirements:

To address this issue, a custom servlet is desired with the following characteristics:

• No external dependencies
• Simple and reliable
• Supports If-Modified-Since header (customizable getLastModified method)
• Optional support for gzip encoding, etags, etc.

Mapping Considerations:

To achieve the desired URL structure (detailed in the question), the servlet mapping should resemble the following:

<servlet-mapping>
    <servlet-name>main</servlet-name>
    <url-pattern>/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>default</servlet-name>
    <url-pattern>/static/*</url-pattern>
</servlet-mapping>

Proposed Solution:

While external servlets meeting the requirements are available, a simpler approach has been devised. By mapping content files by extension to the default servlet and everything else to a custom servlet named "myAppServlet," the desired functionality can be achieved. The resulting mapping would be:

<servlet-mapping>
    <servlet-name>default</servlet-name>
    <url-pattern>*.html</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>default</servlet-name>
    <url-pattern>*.jpg</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>default</servlet-name>
    <url-pattern>*.png</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>default</servlet-name>
    <url-pattern>*.css</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>default</servlet-name>
    <url-pattern>*.js</url-pattern>
</servlet-mapping>

<servlet-mapping>
    <servlet-name>myAppServlet</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>

Advantages:

This approach ensures that requests for static content (images, CSS, etc.) are handled by the default servlet, while all other requests are routed to the custom servlet. It works seamlessly with both Jetty and Tomcat containers.

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