Spring MVC - Enabling RequestMappingHandlerMapping#useRegisteredSuffixPatternMatch in Spring 6.x

The useRegisteredSuffixPatternMatch configuration option allows you to map requests based on a file extension appended to the URL path (for example, /users.json or /data.xml) while restricting this behavior to only the extensions you have explicitly registered for content negotiation. In older Spring MVC applications, this was a common technique for content negotiation, enabling a single endpoint to serve different formats based on the URL suffix.

Check out this example to understand how it works .

A Brief History: Why Is It Disabled?

The feature was deprecated as of Spring Framework 5.2.4 and subsequently removed in later versions (including Spring 6.x) in order to discourage the use of path extensions for both request mapping and content negotiation[reference:0][reference:1]. The primary motivation behind this change is security. Using path extensions for content negotiation can lead to ambiguous and potentially dangerous request mappings. For instance, a path like /users/{id} could be misinterpreted if the {id} value itself contains a dot (e.g., /users/John.Doe). This ambiguity can create vulnerabilities, such as path traversal or unexpectedly matching a different handler than intended[reference:2].

Consequently, the Spring team removed these options without direct replacement[reference:3]. The recommended modern alternatives are:

• Using the Accept header: This is the most explicit and standard HTTP mechanism for content negotiation. Clients specify the desired media type (e.g., application/json, application/xml) in the request header.
• Using a query parameter: You can enable content negotiation via a query parameter (e.g., /users?format=json) using the favorParameter(true) configuration.

While the configuration shown below can force Spring 5.3+/6.x to re-enable this legacy behavior, it relies on deprecated classes and APIs. For new development, it is strongly advised to use one of the recommended, secure alternatives to avoid potential issues and ensure compatibility with future Spring Framework releases.

Example Project

Dependencies and Technologies Used:

• spring-webmvc 6.0.0 (Spring Web MVC)
  
• spring-test 6.0.0 (Spring TestContext Framework)
  
• junit-jupiter-engine 5.8.2 (Module "junit-jupiter-engine" of JUnit 5)
  
• jakarta.servlet-api 6.0.0 (Jakarta Servlet API documentation)
  
• hamcrest 3.0 (Core API and libraries of hamcrest matcher framework)
  
• JDK 17
• Maven 3.9.11