如何在Java + Spring中正确使用@PathVariable？

Question

I have a controller that works fine for other request mappings, but I'm having trouble getting one to work with the @PathVariable annotation.

In this example (see "URI Template Patterns") it has this example:

@RequestMapping(value="/owners/{ownerId}", method=RequestMethod.GET)
public String findOwner(@PathVariable String ownerId, Model model) {
    Owner owner = ownerService.findOwner(ownerId);
    model.addAttribute("owner", owner);
    return "displayOwner";
}

My code looks like this:

@RequestMapping( value="/ViewReport/json", method = RequestMethod.GET)
public ModelAndView TestJson(final Model model){
    model.addAttribute("fnord", "{\"hello\":\"awesome\"}"); 
    return new ModelAndView("reportViewJson");  
}    

@RequestMapping( value="/ViewReport/jayson/{foobar}", method = RequestMethod.GET)
public ModelAndView TestJayz(final Model model, @PathVariable String foobar){
    model.addAttribute("fnord", "{\"hello\":\""+foobar+"\"}");  
    return new ModelAndView("reportViewJson");  
} 

Then I have a web.xml file containing this:

  <servlet-mapping>
    <servlet-name>autoreport</servlet-name>
    <url-pattern>/ViewReport/jayson/*</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>autoreport</servlet-name>
    <url-pattern>/ViewReport/json</url-pattern>
  </servlet-mapping>

Now, when I navigate to /ViewReport/json , I get the JSON {"hello": "awesome"} as I would expect. However, when I navigate to /ViewReport/jayson/42 I get

HTTP Status 404 -

type Status report

message

description The requested resource () is not available.

Apache Tomcat/7.0.29

What am I doing wrong with my usage of the PathVariable , and what do I need to do to fix it?

Update

When my server starts up it spits out these lines:

[ INFO] 14:15(AbstractUrlHandlerMapping.java:registerHandler:315)
Mapped URL path [/ViewReport/json.*] onto handler 'reportViewController'

[DEBUG] 14:15(AbstractBeanFactory.java:doGetBean:246)
Returning cached instance of singleton bean 'reportViewController'

[ INFO] 14:15(AbstractUrlHandlerMapping.java:registerHandler:315)
Mapped URL path [/ViewReport/json/] onto handler 'reportViewController'

[DEBUG] 14:15(AbstractBeanFactory.java:doGetBean:246)
Returning cached instance of singleton bean 'reportViewController'

[ INFO] 14:15(AbstractUrlHandlerMapping.java:registerHandler:315)
Mapped URL path [/ViewReport/jayson/{foobar}] onto handler 'reportViewController'

And when I make the request I get this:

[DEBUG] 20:45(DispatcherServlet.java:doService:823)
DispatcherServlet with name 'autoreport' processing GET request for [/ViewReport/jayson/fnord]

[ WARN] 20:45(DispatcherServlet.java:noHandlerFound:1108)
No mapping found for HTTP request with URI [/ViewReport/jayson/fnord] in DispatcherServlet with name 'autoreport'

Answer 1

Spring has magic; parameter order matters. Try inverting the order of your handler parameters. Instead of this:

public ModelAndView TestJayz(final Model model, @PathVariable String foobar)

Try this:

public ModelAndView TestJayz(@PathVariable String foobar, final Model model)

Take 2:

Try changing the mapping in your web.xml to something more generic. For example:

<servlet-mapping>
    <servlet-name>autoreport</servlet-name>
    <url-pattern>/ViewReport/*</url-pattern>
</servlet-mapping>

I used /spring/* in my test web.xml, @RequestMapping("/blammy/{value}") in my controller, then sent the request to "{WEBROOT}/spring/blammy/testvalue" where "{WEBROOT}" was the web-root of my test app.

Answer 2

request mappings a relative to the dispatcher servlet mapping (by default, see alwaysUseFullPath property in DefaultAnnotationHandlerMapping and AnnotationMethodHandlerAdapter for more information).

if you request a resource /ViewReport/jayson/fnord spring mvc is looking for a handler mapped to fnord .

you would need to request /ViewReport/jayson/ViewReport/jayson/fnord

Answer 3

Have you tried @PathVariable(value="foobar") String foobar ?

@RequestMapping( value="/ViewReport/jayson/{foobar}", method = RequestMethod.GET)
public ModelAndView TestJayz(final Model model, @PathVariable(value="foobar") String foobar){
    model.addAttribute("fnord", "{\"hello\":\""+foobar+"\"}");  
    return new ModelAndView("reportViewJson");  
}