How to Return HTTP Error Codes with @ResponseBody in Spring MVC?

How to Handle HTTP Errors in Spring MVC @ResponseBody Methods

When using Spring MVC @ResponseBody to return JSON in a RESTful API, it's essential to handle HTTP errors gracefully. One common error code is 400 (Bad Request). This error code indicates that the request is invalid due to missing or incorrect parameters.

In the given scenario, where the return type of the method is String, one can change the method's signature to return ResponseEntity<> instead. ResponseEntity<> allows you to specify both the body of the response and the HTTP status code.

To respond with an HTTP 400 error, you can return a ResponseEntity with a null body and an appropriate HTTP status code. Here's an example:

<code class="java">@RequestMapping(value = "/matches/{matchId}", produces = "application/json")
@ResponseBody
public ResponseEntity<String> match(@PathVariable String matchId) {
    String json = matchService.getMatchJson(matchId);
    if (json == null) {
        return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
    }
    return new ResponseEntity<>(json, HttpStatus.OK);
}</code>

Alternatively, Spring 4.1 introduced helper methods in ResponseEntity that simplify this process even further. You can now use:

<code class="java">return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(null);</code>

or for a successful request:

<code class="java">return ResponseEntity.ok(json);</code>

By handling HTTP errors appropriately, you ensure a consistent and user-friendly experience in your RESTful API.

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