How to access plain JSON body in Spring REST controller?

Question

Having the following code:

@RequestMapping(value = "/greeting", method = POST, consumes = APPLICATION_JSON_VALUE, produces = APPLICATION_JSON_VALUE)
@ResponseBody
public String greetingJson(@RequestBody String json) {
    System.out.println("json = " + json); // TODO json is null... how to retrieve plain json body?
    return "Hello World!";
}

The String json argument is always null despite JSON being sent in the body.

Note that I don't want automatic type conversion, I just want the plain JSON result.

This for example works:

@RequestMapping(value = "/greeting", method = POST, consumes = APPLICATION_JSON_VALUE, produces = APPLICATION_JSON_VALUE)
@ResponseBody
public String greetingJson(@RequestBody User user) {
    return String.format("Hello %s!", user);
}

Probably I can use the use the ServletRequest or InputStream as argument to retrieve the actual body, but I wonder if there is an easier way?

Answer 1

Best way I found until now is:

@RequestMapping(value = "/greeting", method = POST, consumes = APPLICATION_JSON_VALUE, produces = APPLICATION_JSON_VALUE)
@ResponseBody
public String greetingJson(HttpEntity<String> httpEntity) {
    String json = httpEntity.getBody();
    // json contains the plain json string

Let me know if there are other alternatives.