spring-mvc return raw json string - json

Question

I want the convenience of automatically serializing objects into JSON and ability to return raw JSON string. I am using Gson instead of Jackson, since Gson has been in my app for a while and I have existing tweaks, converters, and annotations peppered throughout my app.
<mvc:annotation-driven >
<mvc:message-converters register-defaults="true">
<bean class="com.test.GSONHttpMessageConverter" />
</mvc:message-converters>
</mvc:annotation-driven>
I can automatically serialize pojo's:
#RequestMapping(value="foo/{name}", method = RequestMethod.GET)
public #ResponseBody Shop getShopInJSON(#PathVariable String name) {
return new Shop();
}
I want this to work also:
#RequestMapping(value="rawJsonTest/{name}", method = RequestMethod.GET, produces=MediaType.APPLICATION_JSON_VALUE)
public #ResponseBody String rawJsonTest(#PathVariable String name) {
return "{\"test\":5}";
}
Result right now is an escaped value:
"{\"test\":5}"
instead of:
{"test":5}

Answer 1

The problem is that your custom converter takes precedence over the default ones. It's thus called, considers the String as a raw String that must be converted to JSON, and thus escapes the double quotes.
I'm not sure if and how it's possible with XML to register a converter after (and not before) the default ones, but you could set register-defaults to false and provide an explicit list of all the converters you want to apply. If org.springframework.http.converter.StringHttpMessageConverter is registered before your custom one, it will be called first and will send the returned String as is.

Answer 2

Thanks for the correct answer, #JB Nizet
Order matters:
<mvc:annotation-driven >
<mvc:message-converters register-defaults="true">
<bean class = "org.springframework.http.converter.StringHttpMessageConverter">
<property name="supportedMediaTypes" value="application/json; charset=UTF-8" />
</bean>
<bean class="com.test.GSONHttpMessageConverter" />
</mvc:message-converters>