Spring @RequestMapping消耗charset？

Question

I'm trying to use @RequestMapping with the consumes -element. Reading the API-document it works on the Content-Type -header of the request. However, using

@RequestMapping(consumes = "application/x-www-form-urlencoded;charset=UTF-8", value = "/test")
public void test() {
  :
}

or

@RequestMapping(consumes = "application/x-www-form-urlencoded;charset=ISO-8859-1", value = "/test")
public void test() {
  :
}

doesn't make a difference. The header in the request can look like

Content-Type: application/x-www-form-urlencoded;charset=UTF-8

or

Content-Type: application/x-www-form-urlencoded

test() will be called in all four possible constellations.

However, and this is proof to me that Spring sees and tries to use the charset -part, if I specify

@RequestMapping(consumes = "application/x-www-form-urlencoded;charset=UTF-x8", value = "/test")
public void test() {
  :
}

I get an exception during startup (!) of the web-app:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping#0': Initialization of bean failed;
    nested exception is java.nio.charset.UnsupportedCharsetException: UTF-x8

Note that the documentation on the produces -element also doesn't mention the use of charset , but according to Google some use it.

Any clues to what's happening here or what I'm doing wrong?

BTW, this is Spring 3.1.1.RELEASE.

Answer 1

I think you have already answered your question, so this is more of a confirmation, from a code point of view, as to why the charset is not taken into account when resolving mappings.

When digging into Spring code, the culprit seems to be the MediaType#includes() . method

More digging reveals that a RequestMappingInfo is created in association to the RequestMapping annotation of the method. This RequestMappingInfo stores a series of AbstractRequestCondition objects, one of them being the ConsumesRequestCondition which holds the MediaType defined in the consumes part of the annotation (ie application/x-www-form-urlencoded;charset=UTF-8 ).

Later when a request is made, this ConsumesRequestCondition has an inner ConsumeMediaTypeExpression class with a matchMediaType() method that extracts the MediaType of the HttpServletRequest and checks it against it's own MediaType to see if it's included.

If you look at the MediaType#includes() implementation (Lines 426 to 428), it returns true when type (ie application ) and subtype (ie x-www-form-urlencoded ) are equal, completely disregarding the parameters Map which in this case holds the remnant "charset","UTF-8" combination.

Digging into the produces track seems to show similar results, but in this case it's the MediaType#isCompatibleWith() method involved, and again, it reaches only to type and subtype if they are equal.

If you found evidence on Google of the produces working for charset request mapping, I would doubt it (unless they changed core Spring stuff)

As to why it was designed this way, well that's another question :)