SpringMVC：依赖于url扩展的不一致映射行为

Question

@RestController
@RequestMapping(ThemeEndpoint.ENDPOINT_NAME)
public class ThemeEndpoint {

public static final String ENDPOINT_NAME = "/themes"; 

    @RequestMapping(value="/{id}/css/{assetName:.*}", method=RequestMethod.GET)
    public Asset getCssItem(
        @PathVariable("id") ThemeId id, 
        @PathVariable("assetName") String name) {
    CssThemeAsset themeAsset = themeService.getCssAsset(
                id, ThemeAssetId.fromString(name));
    Asset asset = new Asset();
    asset.name = themeAsset.getName();
    asset.text = themeAsset.getContent();
    return asset;
}

http://localhost:8080/app-url/rest/themes/ac18a080-a2f1-11e3-84f4-600308a0bd14/css/main.less

但当我将扩展名更改为.css时就会失败。

经过一些调试后，我确信如果使用类似的url的话，请求甚至不会被映射

http://localhost:8080/app-url/rest/themes/ac18a080-a2f1-11e3-84f4-600308a0bd14/css/main.css

对于高日志级别,我可以看到映射被Spring捕获：

org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping 
    - Mapped "{[/themes/{id}/css/{assetName:.*}],methods=[GET],params=[],headers=[],
                consumes=[],produces=[application/json],custom=[]}" 
      onto public xxx.endpoint.ThemeEndpoint$Asset
          xxx.endpoint.ThemeEndpoint.getCssItem(
              net.lacho.svc.themes.api.ThemeId,java.lang.String)   

Found 1 matching mapping(s) for [/themes/ac18a080-a2f1-11e3-84f4-600308a0bd14/css/main.less]
  : [{[/themes/{id}/css/{assetName:.*}],methods=[GET],params=[],headers=[],
        consumes=[],produces=[application/json],custom=[]}]

Looking up handler method for path /themes/ac18a080-a2f1-11e3-84f4-600308a0bd14/css/test.css
org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver - 
    Resolving exception from handler [null]:  
org.springframework.web.HttpMediaTypeNotAcceptableException: 
    Could not find acceptable representation

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
        http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    version="3.0"
    metadata-complete="false">

<welcome-file-list>
    <welcome-file>index</welcome-file>
</welcome-file-list>

</web-app>

package net.lacho.opcenter.bootstrap;


public class WebApplicationBootstrapper implements WebApplicationInitializer {


    @Override
    public void onStartup(ServletContext container) throws ServletException {

        AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
        rootContext.setConfigLocation(ApplicationConfig.class.getName());

        container.addListener(new ContextLoaderListener(rootContext));

        registerRestDispatcher(container);
        registerDefaultDispatcher(container);

        container.addFilter("CharacterEncodingFilter", UTF8EncodingFilter.class).addMappingForUrlPatterns(null,  true,  "/*");
        container.addFilter("headSupportFilter", HeadSupportFilter.class).addMappingForUrlPatterns(null,  true,  "/*");

        DelegatingFilterProxy shallowFrontendContextFilterProxy = new DelegatingFilterProxy("shallowFrontendContextProviderLocalFilter");
        shallowFrontendContextFilterProxy.setTargetFilterLifecycle(true);
        FilterRegistration.Dynamic shallowFrontendFilter = container.addFilter("ShallowFrontendContextFilter", shallowFrontendContextFilterProxy);
        shallowFrontendFilter.setInitParameter("ignoreNullClient", "true");
        shallowFrontendFilter.addMappingForUrlPatterns(null,  true,  "/*");

        container.addFilter("springSecurityFilterChain", new DelegatingFilterProxy("springSecurityFilterChain"))
            .addMappingForUrlPatterns(null,  true,  "/*");

        container.addFilter("FrontendContextFilter", new DelegatingFilterProxy("frontendContextProviderLocalFilter"))
            .addMappingForUrlPatterns(null,  true,  "/*");

        container.addFilter("hiddenHttpMethodFilter", new HiddenHttpMethodFilter()).addMappingForUrlPatterns(null,  true,  "/rest/*");;
    }

    public void registerRestDispatcher(ServletContext container) {
        AnnotationConfigWebApplicationContext restDispatcherContext = new AnnotationConfigWebApplicationContext();
        restDispatcherContext.register(RestCommonsMvcConfig.class);

        ServletRegistration.Dynamic restDispatcher = container.addServlet("rest-dispatcher", new DispatcherServlet(restDispatcherContext));
        restDispatcher.setLoadOnStartup(1);
        restDispatcher.addMapping("/rest/*");
    }

    public void registerDefaultDispatcher(ServletContext container) {
        AnnotationConfigWebApplicationContext dispatcherContext = new AnnotationConfigWebApplicationContext();
        dispatcherContext.register(MvcConfig.class);

        ServletRegistration.Dynamic dispatcher = container.addServlet("backend-dispatcher", new DispatcherServlet(dispatcherContext));
        dispatcher.setLoadOnStartup(1);
        dispatcher.addMapping("/*", "/index");
    }

}

MVC-Config：

package net.lacho.opcenter.bootstrap;



@Configuration
@EnableWebMvc
@ComponentScan(basePackages = {"net.lacho.opcenter.ui"} )
public class MvcConfig extends WebMvcConfigurerAdapter {

    ... many lines removed, containing interceptors and velocity-config ...

@Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry
            .addResourceHandler("/_r/_s/**")
            .addResourceLocations("classpath:/static-resources/")
            .setCachePeriod(365 * 86400);
        registry
            .addResourceHandler("/_r/_d/**")
            .addResourceLocations("classpath:/static-uncached-resources/");
    }

    @Override
    public void configureDefaultServletHandling(
            DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

有人知道吗？

Answer 1

不是虫子，是功能...

正如@axtavt和@rhinds所设想的，内容类型中有什么东西在乱搞。浏览器发送正确的accept:application/json，但spring忽略了这一点，而是使用url的扩展名（aarrgh）。从文档中：

16.16.4配置内容协商

You can configure how Spring MVC determines the requested media types from the client for
request mapping as well as for content negotiation purposes. The available options are to 
check the file extension in the request URI, the "Accept" header, a request parameter, as 
well as to fall back on a default content type. By default, file extension in the request 
URI is checked first and the "Accept" header is checked next.

@Configuration
@EnableWebMvc
public class RestCommonsMvcConfig extends WebMvcConfigurerAdapter {

    @Override
    public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
        configurer.favorPathExtension(false);
    }

}

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