Spring Top – Temp

Get started with Spring 5 and Spring Boot 2, through the reference Learn Spring course:

Lightrun – Third Party Code

We rely on other people’s code in our own work. Every day. It might be the language you’re writing in, the framework you’re building on, or some esoteric piece of software that does one thing so well you never found the need to implement it yourself.

The problem is, of course, when things fall apart in production - debugging the implementation of a 3rd party library you have no intimate knowledge of is, to say the least, tricky. It’s difficult to understand what talks to what and, specifically, which part of the underlying library is at fault.

Lightrun is a new kind of debugger.

It's one geared specifically towards real-life production environments. Using Lightrun, you can drill down into running applications, including 3rd party dependencies, with real-time logs, snapshots, and metrics. No hotfixes, redeployments, or restarts required.

Learn more in this quick, 5-minute Lightrun tutorial:

>> The Essential List of Spring Boot Annotations and Their Use Cases

1. Overview

In this quick tutorial, we’ll discuss the new ResponseStatusException class introduced in Spring 5. This class supports the application of HTTP status codes to HTTP responses.

A RESTful application can communicate the success or failure of an HTTP request by returning the right status code in the response to the client. Simply put, an appropriate status code can help the client to identify problems that might have occurred while the application was dealing with the request.

2. ResponseStatus

Before we delve into ResponseStatusException, let's quickly take a look at the @ResponseStatus annotation. This annotation was introduced in Spring 3 for applying HTTP Status code to an HTTP response.

We can use the @ResponseStatus annotation to set the status and reason in our HTTP response:

@ResponseStatus(code = HttpStatus.NOT_FOUND, reason = "Actor Not Found")
public class ActorNotFoundException extends Exception {
    // ...

If this exception is thrown while processing an HTTP request, then the response will include the HTTP status specified in this annotation.

One drawback of the @ResponseStatus approach is that it creates tight coupling with the exception. In our example, all exceptions of type ActorNotFoundException will generate the same error message and status code in the response.

3. ResponseStatusException

ResponseStatusException is a programmatic alternative to @ResponseStatus and is the base class for exceptions used for applying a status code to an HTTP response. It’s a RuntimeException and hence not required to be explicitly added in a method signature.

Spring provides 3 constructors to generate ResponseStatusException:

ResponseStatusException(HttpStatus status)
ResponseStatusException(HttpStatus status, java.lang.String reason)
  HttpStatus status, 
  java.lang.String reason, 
  java.lang.Throwable cause

ResponseStatusException, constructor arguments:

  • status – an HTTP status set to the HTTP response
  • reason – a message explaining the exception set to the HTTP response
  • cause – a Throwable cause of the ResponseStatusException

Note: in Spring, HandlerExceptionResolver intercepts and processes any exception raised and not handled by a Controller.

One of these handlers, ResponseStatusExceptionResolver, looks for any ResponseStatusException or uncaught exceptions annotated by @ResponseStatus and then extracts the HTTP Status code & reason and includes them in the HTTP response.

3.1. ResponseStatusException Benefits

ResponseStatusException usage has few benefits:

  • Firstly, exceptions of the same type can be processed separately and different status codes can be set on the response, reducing tight coupling
  • Secondly, it avoids the creation of unnecessary additional exception classes
  • Finally, it provides more control over exception handling, as the exceptions can be created programmatically

4. Examples

4.1. Generate ResponseStatusException

Now, let's see an example that generates a ResponseStatusException :

public String getActorName(@PathVariable("id") int id) {
    try {
        return actorService.getActor(id);
    } catch (ActorNotFoundException ex) {
        throw new ResponseStatusException(
          HttpStatus.NOT_FOUND, "Actor Not Found", ex);

Spring Boot provides a default /error mapping, returning a JSON response with HTTP status.

Here’s how the response looks:

$ curl -i -s -X GET http://localhost:8081/actor/8
HTTP/1.1 404
Content-Type: application/json;charset=UTF-8
Transfer-Encoding: chunked
Date: Sat, 26 Dec 2020 19:38:09 GMT

    "timestamp": "2020-12-26T19:38:09.426+00:00",
    "status": 404,
    "error": "Not Found",
    "message": "",
    "path": "/actor/8"

Starting from the 2.3 version, Spring Boot doesn't include an error message on the default error page. The reason is to reduce the risk of leaking information to a client

To change the default behavior, we can use a server.error.include-message property.

Let's set it to always and see what happens:

$ curl -i -s -X GET http://localhost:8081/actor/8
HTTP/1.1 404
Content-Type: application/json;charset=UTF-8
Transfer-Encoding: chunked
Date: Sat, 26 Dec 2020 19:39:11 GMT

    "timestamp": "2020-12-26T19:39:11.426+00:00",
    "status": 404,
    "error": "Not Found",
    "message": "Actor Not Found",
    "path": "/actor/8"

As we can see, this time, the response contains an “Actor Not Found” error message.

4.2. Different Status Code – Same Exception Type

Now, let's see how a different status code is set to HTTP response when the same type of exception is raised:

public String updateActorName(
  @PathVariable("id") int id, 
  @PathVariable("name") String name) {
    try {
        return actorService.updateActor(id, name);
    } catch (ActorNotFoundException ex) {
        throw new ResponseStatusException(
          HttpStatus.BAD_REQUEST, "Provide correct Actor Id", ex);

Here's how the response looks:

$ curl -i -s -X PUT http://localhost:8081/actor/8/BradPitt
HTTP/1.1 400
    "timestamp": "2018-02-01T04:28:32.917+0000",
    "status": 400,
    "error": "Bad Request",
    "message": "Provide correct Actor Id",
    "path": "/actor/8/BradPitt"

5. Conclusion

In this quick tutorial, we discussed how to construct a ResponseStatusException in our program.

We also emphasized how it’s programmatically a better way to set HTTP status codes in HTTP Response than @ResponseStatus annotation.

As always, the full source code is available over on GitHub.

Spring bottom

Get started with Spring 5 and Spring Boot 2, through the Learn Spring course:

Generic footer banner
Comments are closed on this article!