Troubleshooting HttpRequestMethodNotSupportedException in Spring Framework: A Detailed Guide

While working with the Spring Framework, it’s not unusual to encounter some exceptions that can throw a wrench in the system. One common example of this is the HttpRequestMethodNotSupportedException. This article aims to thoroughly explain the causes, effects, and possible solutions to this error in the Spring MVC framework.

What is HttpRequestMethodNotSupportedException?

The HttpRequestMethodNotSupportedException is an exception thrown when a request handler doesn’t support a specific request method. As an instance, when you attempt a POST on a handler that’s only configured for GET requests, Spring MVC will react by throwing an HttpRequestMethodNotSupportedException.

org.springframework.web.HttpRequestMethodNotSupportedException: 
Request method 'POST' not supported

Why does HttpRequestMethodNotSupportedException Occur?

This exception usually takes place when incoming requests are mapped to very specific handlers, based on elements like the request method or content-type of the request. The handlers specified in our applications will only accept a limited set of HTTP methods.

For example, consider a controller handling GET requests only:

@Controller
public class MyController {
    @RequestMapping(value = "/example", method = RequestMethod.GET)
    public String example() {
        return "example-page";
    }
}

If we attempt to make a POST request to /example, Spring will throw an HttpRequestMethodNotSupportedException since the handler for this route only supports GET requests.

Handling HttpRequestMethodNotSupportedException

There are multiple strategies to handle this exception, depending on how you want your application to respond. Here are some methods to consider:

1. Make Sure to Specify All Needed HTTP Methods

The easiest way to prevent an HttpRequestMethodNotSupportedException is to ensure that your request handlers are configured to support all the HTTP methods they should.

For example, if a handler needs to support both GET and POST requests, you can configure the handler like this:

@Controller
public class MyController {
    @RequestMapping(value = "/example", method = {RequestMethod.GET, RequestMethod.POST})
    public String example() {
        return "example-page";
    }
}

2. Create a Default Error Page

Spring views this exception as a 405 error. Thus, you can create an error page for this exception specifically.

@Controller
public class MyErrorController implements ErrorController {

    @RequestMapping("/error")
    public String handleError(HttpServletRequest request) {
        Object status = request.getAttribute(RequestDispatcher.ERROR_STATUS_CODE);

        if (status != null) {
            Integer statusCode = Integer.valueOf(status.toString());

            if(statusCode == HttpStatus.METHOD_NOT_ALLOWED.value()) {
                return "error-405";
            }
        }
        return "error";
    }

    @Override
    public String getErrorPath() {
        return "/error";
    }
}

3. Use Spring’s Exception Handler

Spring MVC provides an exception handler, @ExceptionHandler, allowing you to handle exceptions directly without specifying a dedicated error page.

@ControllerAdvice
public class MyExceptionHandler {
    @ExceptionHandler(HttpRequestMethodNotSupportedException.class)
    public String handleException() {
        return "error-405";
    }
}

Conclusion

The HttpRequestMethodNotSupportedException is just one of the many exceptions a Spring developer might encounter. But with the right knowledge and handling, it can become less of a hindrance and more a guidepost for improving your code. Remember, proper request handler configuration, error page implementation, and utilization of Spring’s inbuilt exception handlers, can efficiently resolve this.

If you wish to further explore this topic, you can refer to the official Spring MVC documentation.

Remember, every error or exception is an opportunity to learn more about the framework we’re working on, so happy coding!

References:

• Spring MVC Documentation: https://docs.spring.io/spring-framework/docs/current/reference/html/web.html#mvc
• Spring’s Exception Handler Documentation: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/bind/annotation/ExceptionHandler.html

That’s it! I hope you found this guide helpful. If you have any questions or comments, feel free to drop a line below. Happy coding!