001/* 002 * Copyright 2002-2015 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.web.bind.annotation; 018 019import java.lang.annotation.Documented; 020import java.lang.annotation.ElementType; 021import java.lang.annotation.Retention; 022import java.lang.annotation.RetentionPolicy; 023import java.lang.annotation.Target; 024 025/** 026 * Annotation for handling exceptions in specific handler classes and/or 027 * handler methods. Provides consistent style between Servlet and Portlet 028 * environments, with the semantics adapting to the concrete environment. 029 * 030 * <p>Handler methods which are annotated with this annotation are allowed to 031 * have very flexible signatures. They may have parameters of the following 032 * types, in arbitrary order: 033 * <ul> 034 * <li>An exception argument: declared as a general Exception or as a more 035 * specific exception. This also serves as a mapping hint if the annotation 036 * itself does not narrow the exception types through its {@link #value()}. 037 * <li>Request and/or response objects (Servlet API or Portlet API). 038 * You may choose any specific request/response type, e.g. 039 * {@link javax.servlet.ServletRequest} / {@link javax.servlet.http.HttpServletRequest} 040 * or {@link javax.portlet.PortletRequest} / {@link javax.portlet.ActionRequest} / 041 * {@link javax.portlet.RenderRequest}. Note that in the Portlet case, 042 * an explicitly declared action/render argument is also used for mapping 043 * specific request types onto a handler method (in case of no other 044 * information given that differentiates between action and render requests). 045 * <li>Session object (Servlet API or Portlet API): either 046 * {@link javax.servlet.http.HttpSession} or {@link javax.portlet.PortletSession}. 047 * An argument of this type will enforce the presence of a corresponding session. 048 * As a consequence, such an argument will never be {@code null}. 049 * <i>Note that session access may not be thread-safe, in particular in a 050 * Servlet environment: Consider switching the 051 * {@link org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter#setSynchronizeOnSession 052 * "synchronizeOnSession"} flag to "true" if multiple requests are allowed to 053 * access a session concurrently.</i> 054 * <li>{@link org.springframework.web.context.request.WebRequest} or 055 * {@link org.springframework.web.context.request.NativeWebRequest}. 056 * Allows for generic request parameter access as well as request/session 057 * attribute access, without ties to the native Servlet/Portlet API. 058 * <li>{@link java.util.Locale} for the current request locale 059 * (determined by the most specific locale resolver available, 060 * i.e. the configured {@link org.springframework.web.servlet.LocaleResolver} 061 * in a Servlet environment and the portal locale in a Portlet environment). 062 * <li>{@link java.io.InputStream} / {@link java.io.Reader} for access 063 * to the request's content. This will be the raw InputStream/Reader as 064 * exposed by the Servlet/Portlet API. 065 * <li>{@link java.io.OutputStream} / {@link java.io.Writer} for generating 066 * the response's content. This will be the raw OutputStream/Writer as 067 * exposed by the Servlet/Portlet API. 068 * <li>{@link org.springframework.ui.Model} as an alternative to returning 069 * a model map from the handler method. Note that the provided model is not 070 * pre-populated with regular model attributes and therefore always empty, 071 * as a convenience for preparing the model for an exception-specific view. 072 * </ul> 073 * 074 * <p>The following return types are supported for handler methods: 075 * <ul> 076 * <li>A {@code ModelAndView} object (Servlet MVC or Portlet MVC). 077 * <li>A {@link org.springframework.ui.Model} object, with the view name implicitly 078 * determined through a {@link org.springframework.web.servlet.RequestToViewNameTranslator}. 079 * <li>A {@link java.util.Map} object for exposing a model, 080 * with the view name implicitly determined through a 081 * {@link org.springframework.web.servlet.RequestToViewNameTranslator}. 082 * <li>A {@link org.springframework.web.servlet.View} object. 083 * <li>A {@link String} value which is interpreted as view name. 084 * <li>{@link ResponseBody @ResponseBody} annotated methods (Servlet-only) 085 * to set the response content. The return value will be converted to the 086 * response stream using 087 * {@linkplain org.springframework.http.converter.HttpMessageConverter message converters}. 088 * <li>An {@link org.springframework.http.HttpEntity HttpEntity<?>} or 089 * {@link org.springframework.http.ResponseEntity ResponseEntity<?>} object 090 * (Servlet-only) to set response headers and content. The ResponseEntity body 091 * will be converted and written to the response stream using 092 * {@linkplain org.springframework.http.converter.HttpMessageConverter message converters}. 093 * <li>{@code void} if the method handles the response itself (by 094 * writing the response content directly, declaring an argument of type 095 * {@link javax.servlet.ServletResponse} / {@link javax.servlet.http.HttpServletResponse} 096 * / {@link javax.portlet.RenderResponse} for that purpose) 097 * or if the view name is supposed to be implicitly determined through a 098 * {@link org.springframework.web.servlet.RequestToViewNameTranslator} 099 * (not declaring a response argument in the handler method signature; 100 * only applicable in a Servlet environment). 101 * </ul> 102 * 103 * <p>In Servlet environments, you can combine the {@code ExceptionHandler} annotation 104 * with {@link ResponseStatus @ResponseStatus}, to define the response status 105 * for the HTTP response. 106 * 107 * <p><b>Note:</b> In Portlet environments, {@code ExceptionHandler} annotated methods 108 * will only be called during the render and resource phases - just like 109 * {@link org.springframework.web.portlet.HandlerExceptionResolver} beans would. 110 * Exceptions carried over from the action and event phases will be invoked during 111 * the render phase as well, with exception handler methods having to be present 112 * on the controller class that defines the applicable <i>render</i> method. 113 * 114 * @author Arjen Poutsma 115 * @author Juergen Hoeller 116 * @since 3.0 117 * @see org.springframework.web.context.request.WebRequest 118 * @see org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerExceptionResolver 119 * @see org.springframework.web.portlet.mvc.annotation.AnnotationMethodHandlerExceptionResolver 120 */ 121@Target(ElementType.METHOD) 122@Retention(RetentionPolicy.RUNTIME) 123@Documented 124public @interface ExceptionHandler { 125 126 /** 127 * Exceptions handled by the annotated method. If empty, will default to any 128 * exceptions listed in the method argument list. 129 */ 130 Class<? extends Throwable>[] value() default {}; 131 132}