In Spring MVC, when the DispatcherServlet is mapped to /, it intercepts all incoming requests, including those for static assets like JavaScript, CSS, and images. Since no default handler mappings exist for static resources, such requests often result in 404 errors unless explicitly configured.

Registering a Resource Handler via Bean Definitions

A manual approach involves defining a ResourceHttpRequestHandler bean along with a SimpleUrlHandlerMapping to associate URL patterns with the handler:

<bean id="staticFileHandler" class="org.springframework.web.servlet.resource.ResourceHttpRequestHandler">
    <property name="locations" value="classpath:/static-assets/"></property>
</bean>

<bean class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
    <property name="mappings">
        <props>
            <prop key="/assets/**">staticFileHandler</prop>
        </props>
    </property>
</bean>

Here, requests matching /assets/** are served from the classpath:/static-assets/ directory. This method is less common now, having been superseded by annotation-based or namespace configurations.

Using the MVC Namespace for Simplified Configuration

The <mvc:resources> tag streamlines resource handling by internal registering a ResourceHttpRequestHandler with a SimpleUrlHandlerMapping:

<mvc:resources mapping="/assets/**" location="/static-content/" />

This maps URLs under /assets/ to files located in the web application's /static-content/ folder, offering concise setup.

Leveraging the Container’s Default Servlet

For a DispatcherServlet mapped to /, Spring MVC provides <mvc:default-servlet-handler/>. It registers DefaultServletHttpRequestHandler with a catch-all pattern /** and the lowest precedence, delegating requests to the servlet container’s default servlet:

<mvc:default-servlet-handler />

If the container uses a non-standard default servlet name, specify it explicitly:

<mvc:default-servlet-handler default-servlet-name="customDefault"/>

Because delegation relies on the container’s default servlet, its name and behavior vary by server (e.g., Tomcat, Jety). This approach avoids extra forwarding steps, improving performance, but cannot serve classpath-resident resources.

Direct Default Servlet Mapping in web.xml

To bypass Spring MVC entirely for static content, map the container’s default servlet directly in web.xml, placing it before other servlet mappings to ensure earliest matching:

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

This yields optimal performance for publicly accessible static paths but does not resolve resources bundled in the classpath.

Each strategy involves trade-offs: direct default servlet usage maximizes speed but limits resource scope; <mvc:resources> balances simplicity and flexibility; explicit handler mappings offer fine-grained control at the cost of verbosity.