Spring MVC - Why not able to use @RequestBody and @RequestParam together
Solution 1:
The @RequestBody
javadoc states
Annotation indicating a method parameter should be bound to the body of the web request.
It uses registered instances of HttpMessageConverter
to deserialize the request body into an object of the annotated parameter type.
And the @RequestParam
javadoc states
Annotation which indicates that a method parameter should be bound to a web request parameter.
Spring binds the body of the request to the parameter annotated with
@RequestBody
.Spring binds request parameters from the request body (url-encoded parameters) to your method parameter. Spring will use the name of the parameter, ie.
name
, to map the parameter.Parameters are resolved in order. The
@RequestBody
is processed first. Spring will consume all theHttpServletRequest
InputStream
. When it then tries to resolve the@RequestParam
, which is by defaultrequired
, there is no request parameter in the query string or what remains of the request body, ie. nothing. So it fails with 400 because the request can't be correctly handled by the handler method.The handler for
@RequestParam
acts first, reading what it can of theHttpServletRequest
InputStream
to map the request parameter, ie. the whole query string/url-encoded parameters. It does so and gets the valueabc
mapped to the parametername
. When the handler for@RequestBody
runs, there's nothing left in the request body, so the argument used is the empty string.The handler for
@RequestBody
reads the body and binds it to the parameter. The handler for@RequestParam
can then get the request parameter from the URL query string.The handler for
@RequestParam
reads from both the body and the URL query String. It would usually put them in aMap
, but since the parameter is of typeString
, Spring will serialize theMap
as comma separated values. The handler for@RequestBody
then, again, has nothing left to read from the body.
Solution 2:
It's too late to answer this question, but it could help for new readers,
It seems version issues. I ran all these tests with spring 4.1.4 and found that the order of @RequestBody
and @RequestParam
doesn't matter.
- same as your result
- same as your result
- gave
body= "name=abc"
, andname = "abc"
- Same as 3.
-
body ="name=abc"
,name = "xyz,abc"
- same as 5.
Solution 3:
It happens because of not very straight forward Servlet specification. If you are working with a native HttpServletRequest
implementation you cannot get both the URL encode body and the parameters. Spring does some workarounds, which make it even more strange and nontransparent.
In such cases Spring (version 3.2.4) re-renders a body for you using data from the getParameterMap()
method. It mixes GET and POST parameters and breaks the parameter order. The class, which is responsible for the chaos is ServletServerHttpRequest
. Unfortunately it cannot be replaced, but the class StringHttpMessageConverter
can be.
The clean solution is unfortunately not simple:
- Replacing
StringHttpMessageConverter
. Copy/Overwrite the original class adjusting methodreadInternal()
. - Wrapping
HttpServletRequest
overwritinggetInputStream()
,getReader()
andgetParameter*()
methods.
In the method StringHttpMessageConverter#readInternal following code must be used:
if (inputMessage instanceof ServletServerHttpRequest) {
ServletServerHttpRequest oo = (ServletServerHttpRequest)inputMessage;
input = oo.getServletRequest().getInputStream();
} else {
input = inputMessage.getBody();
}
Then the converter must be registered in the context.
<mvc:annotation-driven>
<mvc:message-converters register-defaults="true/false">
<bean class="my-new-converter-class"/>
</mvc:message-converters>
</mvc:annotation-driven>
The step two is described here: Http Servlet request lose params from POST body after read it once