Spring控制器中的异常处理

实际上，通常需要集中处理控制器甚至整个应用程序中的异常。在本文中，我们将分析Spring框架提供的解决此问题的主要功能，并通过简单的示例，让我们了解一切的工作原理。谁对此主题感兴趣-欢迎参加！

最初，在Spring 3.2之前，处理应用程序中异常的主要方法是HandlerExceptionResolver和@ExceptionHandler注解。我们将在下面更详细地分析它们，但是它们具有某些缺点。从3.2版开始，出现了@ControllerAdvice批注，该批注消除了先前解决方案的限制。在春季5中，添加了一个新的ResponseStatusException类，该类对于处理REST API的基本错误非常方便。

现在，首先要开始！

控制器异常处理-@ExceptionHandler

@ExceptionHandler . , , .

:

@RestController
public class Example1Controller {

    @GetMapping(value = "/testExceptionHandler", produces = APPLICATION_JSON_VALUE)
    public Response testExceptionHandler(@RequestParam(required = false, defaultValue = "false") boolean exception)
            throws BusinessException {
        if (exception) {
            throw new BusinessException("BusinessException in testExceptionHandler");
        }
        return new Response("OK");
    }

    @ExceptionHandler(BusinessException.class)
    public Response handleException(BusinessException e) {
        return new Response(e.getMessage());
    }

}

testExceptionHandler, BusinessException, — . , , .

handleException . @ExceptionHandler(BusinessException.class), BusinessException. @ExceptionHandler , : @ExceptionHandler({BusinessException.class, ServiceException.class}).

— 200 JSON . , @ResponseStatus, @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR).

:

:

@ExceptionHandler , . @ExceptionHandler , , , .

HandlerExceptionResolver

HandlerExceptionResolver Spring. HandlerExceptionResolver. , , Spring . :

ExceptionHandlerExceptionResolver — @ExceptionHandler, .

DefaultHandlerExceptionResolver — Spring , :

, REST API . . ModelAndView, , .

ResponseStatusExceptionResolver — @ResponseStatus.

ServiceException:

@ResponseStatus(value = HttpStatus.INTERNAL_SERVER_ERROR)
public class ServiceException extends Exception {

    public ServiceException(String message) {
        super(message);
    }

}

ServiceException @ResponseStatus value INTERNAL_SERVER_ERROR, - 500.

:

@RestController
public class Example2Controller {

    @GetMapping(value = "/testResponseStatusExceptionResolver", produces = APPLICATION_JSON_VALUE)
    public Response testResponseStatusExceptionResolver(@RequestParam(required = false, defaultValue = "false") boolean exception)
            throws ServiceException {
        if (exception) {
            throw new ServiceException("ServiceException in testResponseStatusExceptionResolver");
        }
        return new Response("OK");
    }

}

GET- exception=true, 500- :

— . , @ResponseStatus .

HandlerExceptionResolver , - JSON XML . , .

:

@Component
public class CustomExceptionResolver extends AbstractHandlerExceptionResolver {

    @Override
    protected ModelAndView doResolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
        ModelAndView modelAndView = new ModelAndView(new MappingJackson2JsonView());
        if (ex instanceof CustomException) {
            modelAndView.setStatus(HttpStatus.BAD_REQUEST);
            modelAndView.addObject("message", "CustomException was handled");
            return modelAndView;

        }
        modelAndView.setStatus(HttpStatus.INTERNAL_SERVER_ERROR);
        modelAndView.addObject("message", "Another exception was handled");
        return modelAndView;
    }

}

, . , : , ModelAndView. JSON, .

-, . . , . , — :

@RestController
public class Example3Controller {

    @GetMapping(value = "/testCustomExceptionResolver", produces = APPLICATION_JSON_VALUE)
    public Response testCustomExceptionResolver(@RequestParam(required = false, defaultValue = "false") boolean exception)
            throws CustomException {
        if (exception) {
            throw new CustomException("CustomException in testCustomExceptionResolver");
        }
        return new Response("OK");
    }

}

:

200 JSON .

@ControllerAdvice

— . Spring 3.2 @ControllerAdvice.

:

@ControllerAdvice
public class DefaultAdvice {

    @ExceptionHandler(BusinessException.class)
    public ResponseEntity<Response> handleException(BusinessException e) {
        Response response = new Response(e.getMessage());
        return new ResponseEntity<>(response, HttpStatus.OK);
    }

}

, @ControllerAdvice , .

DefaultAdvice handleException. handleException @ExceptionHandler, , , . BusinessException.

: @ExceptionHandler({BusinessException.class, ServiceException.class}). @ExceptionHandler .

, handleException ResponseEntity Response:

public class Response {

    private String message;

    public Response() {
    }

    public Response(String message) {
        this.message = message;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

}

, JSON . message HttpStatus.OK, 200.

:

@RestController
public class Example4Controller {

    @GetMapping(value = "/testDefaultControllerAdvice", produces = APPLICATION_JSON_VALUE)
    public Response testDefaultControllerAdvice(@RequestParam(required = false, defaultValue = "false") boolean exception)
            throws BusinessException {
        if (exception) {
            throw new BusinessException("BusinessException in testDefaultControllerAdvice");
        }
        return new Response("OK");
    }

}

, , JSON 200:

?

! :

@ControllerAdvice(annotations = CustomExceptionHandler.class)
public class CustomAdvice {

    @ExceptionHandler(BusinessException.class)
    public ResponseEntity<Response> handleException(BusinessException e) {
        String message = String.format("%s %s", LocalDateTime.now(), e.getMessage());
        Response response = new Response(message);
        return new ResponseEntity<>(response, HttpStatus.OK);
    }

}

@ControllerAdvice(annotations = CustomExceptionHandler.class). CustomAdvice , @CustomExceptionHandler.

@CustomExceptionHandler :

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface CustomExceptionHandler {
}

:

@RestController
@CustomExceptionHandler
public class Example5Controller {

    @GetMapping(value = "/testCustomControllerAdvice", produces = APPLICATION_JSON_VALUE)
    public Response testCustomControllerAdvice(@RequestParam(required = false, defaultValue = "false") boolean exception)
            throws BusinessException {
        if (exception) {
            throw new BusinessException("BusinessException in testCustomControllerAdvice");
        }
        return new Response("OK");
    }

}

Example5Controller @CustomExceptionHandler, Example4Controller . BusinessException CustomAdvice, DefaultAdvice, .

CustomAdvice — :

. @ControllerAdvice, . .

ResponseStatusException.

ResponseStatusException:

@RestController
public class Example6Controller {

    @GetMapping(value = "/testResponseStatusException", produces = APPLICATION_JSON_VALUE)
    public Response testResponseStatusException(@RequestParam(required = false, defaultValue = "false") boolean exception) {
        if (exception) {
            throw new ResponseStatusException(HttpStatus.INTERNAL_SERVER_ERROR, "ResponseStatusException in testResponseStatusException");
        }
        return new Response("OK");
    }

}

ResponseStatusException , , . @ResponseStatus — -. , .

:

简介：我们已经看到了处理异常的不同方法，每种方法都有其自身的特征。在大型应用程序中，您可以一次找到几种方法，但是您需要非常小心，并且不要使错误处理逻辑过于复杂。否则，将会发现某些异常将在错误的处理程序中处理，并且响应将不同于预期的响应。例如，如果应用程序有多个顾问程序，则在创建新顾问程序时，您需要确保它不会破坏处理旧控制器异常的现有顺序。

所以要小心，一切都会很好！

链接到文章的来源