How to Access Static Resources with a Global Front Controller Servlet Mapped to /*?

Accessing Static Resources when Mapping Global Front Controller Servlet on /*

Mapping a global front controller servlet on /* can prevent the access to static resources such as CSS, JS, and images. To resolve this, consider the following steps:

Map the Controller Servlet on a More Specific URL Pattern

Instead of mapping the servlet on /, use a more specific pattern like /pages/. This allows static content to be stored in a separate folder, such as /static.

Create a Filter for Handling Static Content

Create a filter that listens on /* and transparently handles requests for static content by forwarding them to the default servlet. For any other requests, the filter should dispatch to the controller servlet.

Here's an example of a filter configuration:

<filter>
    <filter-name>filter</filter-name>
    <filter-class>com.example.Filter</filter-class>
</filter>
<filter-mapping>
    <filter-name>filter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

Filter Implementation:

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;

public class Filter implements Filter {

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws ServletException, IOException {
        HttpServletRequest req = (HttpServletRequest) request;
        String path = req.getRequestURI().substring(req.getContextPath().length());

        if (path.startsWith("/static")) {
            chain.doFilter(request, response); // Goes to default servlet.
        } else {
            request.getRequestDispatcher("/pages" + path).forward(request, response);
        }
    }

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }

    @Override
    public void destroy() {
    }
}

Controller Servlet Mapping:

<servlet>
    <servlet-name>controller</servlet-name>
    <servlet-class>com.example.Controller</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>controller</servlet-name>
    <url-pattern>/pages/*</url-pattern>
</servlet-mapping>

This approach allows static content to be served transparently while directing other requests to the controller servlet.

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