Java – How to respond with HTTP 400 error in a Spring MVC @ResponseBody method returning String

http-errorjavaspringspring-mvc

I'm using Spring MVC for a simple JSON API, with @ResponseBody based approach like the following. (I already have a service layer producing JSON directly.)

@RequestMapping(value = "/matches/{matchId}", produces = "application/json")
@ResponseBody
public String match(@PathVariable String matchId) {
    String json = matchService.getMatchJson(matchId);
    if (json == null) {
        // TODO: how to respond with e.g. 400 "bad request"?
    }
    return json;
}

Question is, in the given scenario, what is the simplest, cleanest way to respond with a HTTP 400 error?

I did come across approaches like:

return new ResponseEntity(HttpStatus.BAD_REQUEST);

…but I can't use it here since my method's return type is String, not ResponseEntity.

Best Answer

change your return type to ResponseEntity<>, then you can use below for 400

return new ResponseEntity<>(HttpStatus.BAD_REQUEST);

and for correct request

return new ResponseEntity<>(json,HttpStatus.OK);

UPDATE 1

after spring 4.1 there are helper methods in ResponseEntity could be used as

return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(null);

and

return ResponseEntity.ok(json);

Related Solutions

Ajax – Handling JSON and form data request with Spring MVC

First, the above declaration won't compile, because you are having duplicate signature.

Btw, @Consumes wouldn't help, I think, because it only designates what content type the method can handle.

In spring you can specify the content-type with

@RequestMapping(headers="Content-Type=application/json")

Java – Spring MVC returning JSONS and exception Handling

Create a response class:

public class Response<T> {
    T data;
    boolean status = true;

    public Response(T d) { data = d; }
}

Then return that from your controllers:

@ResponseBody public Response getUserDetails) {
    //...
    return new Response(userDetails);
}

For the exception you'll want to return an object like:

public class BadStatus {
    String errorMessage;
    boolean status = false;

    public BadStatus(String msg) { errorMessage = msg; }
}

@ExceptionHandler(Exception.class)
public BadStatus handleException(Exception ex, HttpServletRequest request) {
  return new BadStatus(ex.getMessage());
}

Best Answer

Related Solutions

Ajax – Handling JSON and form data request with Spring MVC

Java – Spring MVC returning JSONS and exception Handling

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