Hi,

I'm developing a Spring MVC app using Spring Boot 2.4.1.

I add the following configurations to application.properties in order to switch path matching strategy to the new PathPatternParser:

spring.mvc.pathmatch.matching-strategy=path_pattern_parser

But after that access to the root path (/) won't be redirected to /index.html. Access the full path http://xxxxx/index.html is OK. If switching back to AntPathMatcher, redirect works normally.

PS: I set spring.web.resources.static-locations to a local directory which contains static resources.

Comment From: samotoo

Hi,

By tracking down the code I find something relates to the issue.

In ResourceHttpRequestHandler.java (spring-webmvc 5.3.2):

...
protected Resource getResource(HttpServletRequest request) throws IOException {
    String path = (String) request.getAttribute(HandlerMapping.PATH_WITHIN_HANDLER_MAPPING_ATTRIBUTE);
    if (path == null) {
        throw new IllegalStateException("Required request attribute '" +
                HandlerMapping.PATH_WITHIN_HANDLER_MAPPING_ATTRIBUTE + "' is not set");
    }

    path = processPath(path);
    if (!StringUtils.hasText(path) || isInvalidPath(path)) {
        return null;
    }
...

The path variable is get from request attribute HandlerMapping.PATH_WITHIN_HANDLER_MAPPING_ATTRIBUTE，if using AntPathMatcher, it can get the correct path (index.html in this case), but using PathPatternParser, path is an empty string. And later StringUtils.hasText(path) returns false causes the method returning null. Then 404 is returned to the client.

Hope this helps.

Comment From: snicoll

@samotoo thanks for the report, I was able to reproduce the issue (simple app from start.spring.io with an index.html in src/main/resources/static).

In both cases our WelcomePageHandlerMapping is registering the welcome page:

INFO 78870 --- [           main] o.s.b.a.w.s.WelcomePageHandlerMapping    : Adding welcome page: class path resource [static/index.html]

Based on your analysis I can see indeed two code paths where, with AntPathMatcher the pathWithinMapping is index.html (see AbstractUrlHandlerMapping#lookupHandler, whereas the PathPatternMatcher provides a pathWithinMapping of ` (empty string), see the newAbstractUrlHandlerMapping#lookupHandler` introduced in Spring Framework 5.3.

At this point, I'd like the framework team to review the use case so I am going to move this issue there.

Comment From: rstoyanchev

For PathPattern, the DispatcherServlet determines the RequestPath once per request and cache it in a request attribute. The welcome page comes in as "/" initially and results in a forward to "/index.html" but on the forward we don't update the RequestPath and it remains as "/".