What's the difference between getRequestURI and getPathInfo methods in HttpServletRequest?

java

httpservletrequest

url-decoding

spring-mvc

byAlex Kataev·Aug 17, 2024

getRequestURI() method serves up the full path of the client's request, sans the query string but inclusive of the server context and servlet path. On the other hand, getPathInfo() dissects that request path and yields only the section after the servlet path and before the query string, found to be particularly useful in demarcating RESTful parameters.

For instance, take http://www.example.com/app/servlet/extra?query=123:

getRequestURI() results in: /app/servlet/extra
getPathInfo() reveals: /extra

// It's like ordering a full meal vs. only dessert
String uri = request.getRequestURI(); // /app/servlet/extra
String pathInfo = request.getPathInfo(); // /extra

The HttpServletRequest breakdown

Navigating the HttpServletRequest object is comparable to understanding the parts of a complex machine. It's made of the following components significant for precise URL handling:

Context Path: Represented by getContextPath(), it's a prefix showing the application's directory on the server.
Servlet Path: The hierarchal pointer towards the servlet assigned to process the request and forms a part of the complete request URI.
Path Info: An extra dash of path data provided to a servlet, reminiscent of additional query parameters one might find in RESTful services.

Caution: When working with Spring MVC, URL-encoded parts need to be handled with extreme care for security reasons.

Pitfalls in Servlet mapping

The servlet paths mapping configuration is crucial to getPathInfo(). If the servlet mappings are not ended with a wildcard '*', getPathInfo() could disappointingly return null.

Scenario: A servlet mapping configured as /app/*, fields a request /app/servlet/extra, getPathInfo() would be prompted to return /extra.

Dealing with URI processing hiccups

The getPathInfo() method adjusts to the environmental differences between local and production setups. This may cause discrepancies across environments, warranting rigorous testing and configuration validation.

Additional HttpServletRequest methods

The HttpServletRequest object is not limited to getRequestURI() and getPathInfo(), but includes methods to access other components like :

Query Strings: Available via getQueryString(), it refers to the part of the URL that assigns values to custom parameters.
URL Fragments: The part of a URL located after the "#"; it is processed on the client-side and untouched by these methods.

Always remember, getRequestURI() delivers a URL-decoded string, while getPathInfo() may also return URL-decoded path details, a valuable note for encoded data management within URLs.

Servlet specification handbook

The Servlet specification can provide clarifications on the intent and use of getRequestURI() and getPathInfo(). Use examples from the specification to master your understanding of these methods.

Additional tips for programmers

Spring MVC gotchas

In Spring MVC, you can frequently encounter null values for getPathInfo(). The framework's mechanism of servlet mapping may mandate a fallback to getRequestURI() for consistency.

Front-controller pattern requirements

Front-controllers like the DispatcherServlet necessitate a steadfast interpretation of the request path. Hence, decoding getRequestURI() and getPathInfo() is essential for a reliable MVC pattern.

Handling URL decoding

getPathInfo() could already provide URL-decoded path segments. Carefully handling these in order to avoid Double Decoding Vulnerabilities, especially with URL-encoded data employed in routing and path variables, is paramount.

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