Java tutorial
/* * Copyright 2002-2018 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * https://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.web.servlet.mvc.annotation; import java.io.IOException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.springframework.context.MessageSource; import org.springframework.context.MessageSourceAware; import org.springframework.context.i18n.LocaleContextHolder; import org.springframework.core.annotation.AnnotatedElementUtils; import org.springframework.lang.Nullable; import org.springframework.util.StringUtils; import org.springframework.web.bind.annotation.ResponseStatus; import org.springframework.web.server.ResponseStatusException; import org.springframework.web.servlet.ModelAndView; import org.springframework.web.servlet.handler.AbstractHandlerExceptionResolver; /** * A {@link org.springframework.web.servlet.HandlerExceptionResolver * HandlerExceptionResolver} that uses the {@link ResponseStatus @ResponseStatus} * annotation to map exceptions to HTTP status codes. * * <p>This exception resolver is enabled by default in the * {@link org.springframework.web.servlet.DispatcherServlet DispatcherServlet} * and the MVC Java config and the MVC namespace. * * <p>As of 4.2 this resolver also looks recursively for {@code @ResponseStatus} * present on cause exceptions, and as of 4.2.2 this resolver supports * attribute overrides for {@code @ResponseStatus} in custom composed annotations. * * <p>As of 5.0 this resolver also supports {@link ResponseStatusException}. * * @author Arjen Poutsma * @author Rossen Stoyanchev * @author Sam Brannen * @since 3.0 * @see ResponseStatus * @see ResponseStatusException */ public class ResponseStatusExceptionResolver extends AbstractHandlerExceptionResolver implements MessageSourceAware { @Nullable private MessageSource messageSource; @Override public void setMessageSource(MessageSource messageSource) { this.messageSource = messageSource; } @Override @Nullable protected ModelAndView doResolveException(HttpServletRequest request, HttpServletResponse response, @Nullable Object handler, Exception ex) { try { if (ex instanceof ResponseStatusException) { return resolveResponseStatusException((ResponseStatusException) ex, request, response, handler); } ResponseStatus status = AnnotatedElementUtils.findMergedAnnotation(ex.getClass(), ResponseStatus.class); if (status != null) { return resolveResponseStatus(status, request, response, handler, ex); } if (ex.getCause() instanceof Exception) { return doResolveException(request, response, handler, (Exception) ex.getCause()); } } catch (Exception resolveEx) { if (logger.isWarnEnabled()) { logger.warn("Failure while trying to resolve exception [" + ex.getClass().getName() + "]", resolveEx); } } return null; } /** * Template method that handles the {@link ResponseStatus @ResponseStatus} annotation. * <p>The default implementation delegates to {@link #applyStatusAndReason} * with the status code and reason from the annotation. * @param responseStatus the {@code @ResponseStatus} annotation * @param request current HTTP request * @param response current HTTP response * @param handler the executed handler, or {@code null} if none chosen at the * time of the exception, e.g. if multipart resolution failed * @param ex the exception * @return an empty ModelAndView, i.e. exception resolved */ protected ModelAndView resolveResponseStatus(ResponseStatus responseStatus, HttpServletRequest request, HttpServletResponse response, @Nullable Object handler, Exception ex) throws Exception { int statusCode = responseStatus.code().value(); String reason = responseStatus.reason(); return applyStatusAndReason(statusCode, reason, response); } /** * Template method that handles an {@link ResponseStatusException}. * <p>The default implementation delegates to {@link #applyStatusAndReason} * with the status code and reason from the exception. * @param ex the exception * @param request current HTTP request * @param response current HTTP response * @param handler the executed handler, or {@code null} if none chosen at the * time of the exception, e.g. if multipart resolution failed * @return an empty ModelAndView, i.e. exception resolved * @since 5.0 */ protected ModelAndView resolveResponseStatusException(ResponseStatusException ex, HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws Exception { int statusCode = ex.getStatus().value(); String reason = ex.getReason(); return applyStatusAndReason(statusCode, reason, response); } /** * Apply the resolved status code and reason to the response. * <p>The default implementation sends a response error using * {@link HttpServletResponse#sendError(int)} or * {@link HttpServletResponse#sendError(int, String)} if there is a reason * and then returns an empty ModelAndView. * @param statusCode the HTTP status code * @param reason the associated reason (may be {@code null} or empty) * @param response current HTTP response * @since 5.0 */ protected ModelAndView applyStatusAndReason(int statusCode, @Nullable String reason, HttpServletResponse response) throws IOException { if (!StringUtils.hasLength(reason)) { response.sendError(statusCode); } else { String resolvedReason = (this.messageSource != null ? this.messageSource.getMessage(reason, null, reason, LocaleContextHolder.getLocale()) : reason); response.sendError(statusCode, resolvedReason); } return new ModelAndView(); } }