Java tutorial
/* * Copyright 2010 Luke Daley * * 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 * * http://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 grails.plugin.errorpagesfix; import java.io.IOException; import java.io.OutputStreamWriter; import java.io.PrintWriter; import java.io.Writer; import java.util.Collections; import javax.servlet.FilterChain; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.codehaus.groovy.grails.web.errors.GrailsExceptionResolver; import org.codehaus.groovy.grails.web.errors.GrailsWrappedRuntimeException; import org.codehaus.groovy.grails.web.mapping.UrlMappingInfo; import org.codehaus.groovy.grails.web.mapping.UrlMappingsHolder; import org.codehaus.groovy.grails.web.mapping.exceptions.UrlMappingException; import org.codehaus.groovy.grails.web.servlet.mvc.GrailsWebRequest; import org.codehaus.groovy.grails.web.servlet.mvc.GrailsWebRequestFilter; import org.codehaus.groovy.grails.web.servlet.mvc.exceptions.ControllerExecutionException; import org.codehaus.groovy.grails.web.sitemesh.FactoryHolder; import org.codehaus.groovy.grails.web.util.IncludeResponseWrapper; import org.codehaus.groovy.grails.web.util.WebUtils; import org.springframework.web.context.WebApplicationContext; import org.springframework.web.context.request.RequestContextHolder; import org.springframework.web.context.support.WebApplicationContextUtils; import org.springframework.web.multipart.MultipartException; import org.springframework.web.servlet.View; import org.springframework.web.servlet.ViewResolver; import org.codehaus.groovy.grails.web.servlet.*; /** * Copy of the ErrorHandlingServlet in Grails, but changed to use forwards instead of includes. * It also does not do manual layout decoration as it expects the sitemesh filter to do that. * * @see GRAILS-6992 */ public class PatchedErrorHandlingServlet extends GrailsDispatcherServlet { private static final long serialVersionUID = 8792197458391395589L; private static final String TEXT_HTML = "text/html"; private static final String GSP_SUFFIX = ".gsp"; private static final String JSP_SUFFIX = ".jsp"; @Override protected HttpServletRequest checkMultipart(HttpServletRequest request) throws MultipartException { return request; // ignore multipart requests when an error occurs } @Override protected void doDispatch(final HttpServletRequest request, final HttpServletResponse response) throws Exception { int statusCode; if (request.getAttribute("javax.servlet.error.status_code") != null) { statusCode = Integer.parseInt(request.getAttribute("javax.servlet.error.status_code").toString()); } else { statusCode = 500; } Throwable t = null; if (request.getAttribute("javax.servlet.error.exception") != null) { t = (Throwable) request.getAttribute("javax.servlet.error.exception"); if (!(t instanceof GrailsWrappedRuntimeException) && request.getAttribute("exception") == null) { request.setAttribute("exception", new GrailsWrappedRuntimeException(getServletContext(), t)); } } final UrlMappingsHolder urlMappingsHolder = lookupUrlMappings(); UrlMappingInfo matchedInfo = null; if (t != null) { matchedInfo = urlMappingsHolder.matchStatusCode(statusCode, t); if (matchedInfo == null) { matchedInfo = urlMappingsHolder.matchStatusCode(statusCode, GrailsExceptionResolver.getRootCause(t)); } } if (matchedInfo == null) { matchedInfo = urlMappingsHolder.matchStatusCode(statusCode); } final UrlMappingInfo urlMappingInfo = matchedInfo; if (urlMappingInfo != null) { final GrailsWebRequest webRequest = (GrailsWebRequest) RequestContextHolder.getRequestAttributes(); request.setAttribute("com.opensymphony.sitemesh.APPLIED_ONCE", null); urlMappingInfo.configure(webRequest); String viewName = urlMappingInfo.getViewName(); if (viewName == null || viewName.endsWith(GSP_SUFFIX) || viewName.endsWith(JSP_SUFFIX)) { WebUtils.forwardRequestForUrlMappingInfo(request, response, urlMappingInfo, Collections.EMPTY_MAP); } else { ViewResolver viewResolver = WebUtils.lookupViewResolver(getServletContext()); if (viewResolver != null) { View v; try { v = WebUtils.resolveView(request, urlMappingInfo, viewName, viewResolver); IncludeResponseWrapper includeResponse = new IncludeResponseWrapper(response); v.render(Collections.EMPTY_MAP, request, response); } catch (Exception e) { throw new UrlMappingException( "Error mapping onto view [" + viewName + "]: " + e.getMessage(), e); } } } } else { renderDefaultResponse(response, statusCode); } } private void renderDefaultResponse(HttpServletResponse response, int statusCode) throws IOException { if (statusCode == 404) { renderDefaultResponse(response, statusCode, "Not Found", "Page not found."); } else { renderDefaultResponse(response, statusCode, "Internal Error", "Internal server error."); } } private void renderDefaultResponse(HttpServletResponse response, int statusCode, String title, String text) throws IOException { response.setStatus(HttpServletResponse.SC_NOT_FOUND); response.setContentType(TEXT_HTML); Writer writer = response.getWriter(); writer.write("<HTML>\n<HEAD>\n<TITLE>Error " + statusCode + " - " + title); writer.write("</TITLE>\n<BODY>\n<H2>Error " + statusCode + " - " + title + ".</H2>\n"); writer.write(text + "<BR/>"); for (int i = 0; i < 20; i++) { writer.write("\n<!-- Padding for IE -->"); } writer.write("\n</BODY>\n</HTML>\n"); writer.flush(); } private UrlMappingsHolder lookupUrlMappings() { WebApplicationContext wac = WebApplicationContextUtils .getRequiredWebApplicationContext(getServletContext()); return (UrlMappingsHolder) wac.getBean(UrlMappingsHolder.BEAN_ID); } }