org.springframework.web.bind.annotation

## Annotation Type ExceptionHandler

-     @Target(value=METHOD)
      @Retention(value=RUNTIME)
      @Documented
      public @interface ExceptionHandler

  Annotation for handling exceptions in specific handler classes and/or handler methods. Provides consistent style between Servlet and Portlet environments, with the semantics adapting to the concrete environment.

  Handler methods which are annotated with this annotation are allowed to have very flexible signatures. They may have arguments of the following types, in arbitrary order:

  - An exception argument: declared as a general Exception or as a more specific exception. This also serves as a mapping hint if the annotation itself does not narrow the exception types through its `value()`.
  - Request and/or response objects (Servlet API or Portlet API). You may choose any specific request/response type, e.g. `ServletRequest` / `HttpServletRequest` or `PortletRequest` / `ActionRequest` / `RenderRequest`. Note that in the Portlet case, an explicitly declared action/render argument is also used for mapping specific request types onto a handler method (in case of no other information given that differentiates between action and render requests).
  - Session object (Servlet API or Portlet API): either `HttpSession` or `PortletSession`. An argument of this type will enforce the presence of a corresponding session. As a consequence, such an argument will never be `null`. Note that session access may not be thread-safe, in particular in a Servlet environment: Consider switching the `"synchronizeOnSession"` flag to "true" if multiple requests are allowed to access a session concurrently.
  - `WebRequest` or `NativeWebRequest`. Allows for generic request parameter access as well as request/session attribute access, without ties to the native Servlet/Portlet API.
  - `Locale` for the current request locale (determined by the most specific locale resolver available, i.e. the configured `LocaleResolver` in a Servlet environment and the portal locale in a Portlet environment).
  - `InputStream` / `Reader` for access to the request's content. This will be the raw InputStream/Reader as exposed by the Servlet/Portlet API.
  - `OutputStream` / `Writer` for generating the response's content. This will be the raw OutputStream/Writer as exposed by the Servlet/Portlet API.

  The following return types are supported for handler methods:

  - A `ModelAndView` object (Servlet MVC or Portlet MVC).
  - A `Model` object, with the view name implicitly determined through a `RequestToViewNameTranslator`.
  - A `Map` object for exposing a model, with the view name implicitly determined through a `RequestToViewNameTranslator`.
  - A `View` object.
  - A `String` value which is interpreted as view name.
  - `@ResponseBody` annotated methods (Servlet-only) to set the response content. The return value will be converted to the response stream using message converters.
  - An `HttpEntity<?>` or `ResponseEntity<?>` object (Servlet-only) to set response headers and content. The ResponseEntity body will be converted and written to the response stream using message converters.
  - `void` if the method handles the response itself (by writing the response content directly, declaring an argument of type `ServletResponse` / `HttpServletResponse` / `RenderResponse` for that purpose) or if the view name is supposed to be implicitly determined through a `RequestToViewNameTranslator` (not declaring a response argument in the handler method signature; only applicable in a Servlet environment).

  In Servlet environments, you can combine the `ExceptionHandler` annotation with `@ResponseStatus`, to define the response status for the HTTP response.

  Note: In Portlet environments, `ExceptionHandler` annotated methods will only be called during the render and resource phases - just like `HandlerExceptionResolver` beans would. Exceptions carried over from the action and event phases will be invoked during the render phase as well, with exception handler methods having to be present on the controller class that defines the applicable render method.

  Since:
    3.0
  Author:
    Arjen Poutsma, Juergen Hoeller
  See Also:
    `WebRequest`, `AnnotationMethodHandlerExceptionResolver`, `AnnotationMethodHandlerExceptionResolver`

- - ### Optional Element Summary

    Optional Elements
    Modifier and Type | Optional Element and Description
    --- | ---
    `Class<? extends Throwable>[]` | `value` Exceptions handled by the annotation method.

- - ### Element Detail

    - #### value

          public abstract Class<? extends Throwable>[] value

      Exceptions handled by the annotation method. If empty, will default to any exceptions listed in the method argument list.
      Default:
        {}