/*
* Copyright 2002-2016 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
*
* 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 org.springframework.web.servlet.handler;
import java.util.Set;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.core.Ordered;
import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.ModelAndView;
/**
* Abstract base class for {@link HandlerExceptionResolver} implementations.
*
* <p>Supports mapped {@linkplain #setMappedHandlers handlers} and
* {@linkplain #setMappedHandlerClasses handler classes} that the resolver
* should be applied to and implements the {@link Ordered} interface.
*
* @author Arjen Poutsma
* @author Juergen Hoeller
* @author Sam Brannen
* @since 3.0
*/
public abstract class AbstractHandlerExceptionResolver implements HandlerExceptionResolver, Ordered {
private static final String HEADER_CACHE_CONTROL = "Cache-Control";
/** Logger available to subclasses */
protected final Log logger = LogFactory.getLog(getClass());
private int order = Ordered.LOWEST_PRECEDENCE;
private Set<?> mappedHandlers;
private Class<?>[] mappedHandlerClasses;
private Log warnLogger;
private boolean preventResponseCaching = false;
public void setOrder(int order) {
this.order = order;
}
@Override
public int getOrder() {
return this.order;
}
/**
* Specify the set of handlers that this exception resolver should apply to.
* <p>The exception mappings and the default error view will only apply to the specified handlers.
* <p>If no handlers or handler classes are set, the exception mappings and the default error
* view will apply to all handlers. This means that a specified default error view will be used
* as a fallback for all exceptions; any further HandlerExceptionResolvers in the chain will be
* ignored in this case.
*/
public void setMappedHandlers(Set<?> mappedHandlers) {
this.mappedHandlers = mappedHandlers;
}
/**
* Specify the set of classes that this exception resolver should apply to.
* <p>The exception mappings and the default error view will only apply to handlers of the
* specified types; the specified types may be interfaces or superclasses of handlers as well.
* <p>If no handlers or handler classes are set, the exception mappings and the default error
* view will apply to all handlers. This means that a specified default error view will be used
* as a fallback for all exceptions; any further HandlerExceptionResolvers in the chain will be
* ignored in this case.
*/
public void setMappedHandlerClasses(Class<?>... mappedHandlerClasses) {
this.mappedHandlerClasses = mappedHandlerClasses;
}
/**
* Set the log category for warn logging. The name will be passed to the underlying logger
* implementation through Commons Logging, getting interpreted as a log category according
* to the logger's configuration.
* <p>Default is no warn logging. Specify this setting to activate warn logging into a specific
* category. Alternatively, override the {@link #logException} method for custom logging.
* @see org.apache.commons.logging.LogFactory#getLog(String)
* @see org.apache.log4j.Logger#getLogger(String)
* @see java.util.logging.Logger#getLogger(String)
*/
public void setWarnLogCategory(String loggerName) {
this.warnLogger = LogFactory.getLog(loggerName);
}
/**
* Specify whether to prevent HTTP response caching for any view resolved
* by this exception resolver.
* <p>Default is {@code false}. Switch this to {@code true} in order to
* automatically generate HTTP response headers that suppress response caching.
*/
public void setPreventResponseCaching(boolean preventResponseCaching) {
this.preventResponseCaching = preventResponseCaching;
}
/**
* Check whether this resolver is supposed to apply (i.e. if the supplied handler
* matches any of the configured {@linkplain #setMappedHandlers handlers} or
* {@linkplain #setMappedHandlerClasses handler classes}), and then delegate
* to the {@link #doResolveException} template method.
*/
@Override
public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response,
Object handler, Exception ex) {
if (shouldApplyTo(request, handler)) {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Resolving exception from handler [" + handler + "]: " + ex);
}
prepareResponse(ex, response);
ModelAndView result = doResolveException(request, response, handler, ex);
if (result != null) {
logException(ex, request);
}
return result;
}
else {
return null;
}
}
/**
* Check whether this resolver is supposed to apply to the given handler.
* <p>The default implementation checks against the configured
* {@linkplain #setMappedHandlers handlers} and
* {@linkplain #setMappedHandlerClasses handler classes}, if any.
* @param request current HTTP request
* @param handler the executed handler, or {@code null} if none chosen
* at the time of the exception (for example, if multipart resolution failed)
* @return whether this resolved should proceed with resolving the exception
* for the given request and handler
* @see #setMappedHandlers
* @see #setMappedHandlerClasses
*/
protected boolean shouldApplyTo(HttpServletRequest request, Object handler) {
if (handler != null) {
if (this.mappedHandlers != null && this.mappedHandlers.contains(handler)) {
return true;
}
if (this.mappedHandlerClasses != null) {
for (Class<?> handlerClass : this.mappedHandlerClasses) {
if (handlerClass.isInstance(handler)) {
return true;
}
}
}
}
// Else only apply if there are no explicit handler mappings.
return (this.mappedHandlers == null && this.mappedHandlerClasses == null);
}
/**
* Log the given exception at warn level, provided that warn logging has been
* activated through the {@link #setWarnLogCategory "warnLogCategory"} property.
* <p>Calls {@link #buildLogMessage} in order to determine the concrete message to log.
* @param ex the exception that got thrown during handler execution
* @param request current HTTP request (useful for obtaining metadata)
* @see #setWarnLogCategory
* @see #buildLogMessage
* @see org.apache.commons.logging.Log#warn(Object, Throwable)
*/
protected void logException(Exception ex, HttpServletRequest request) {
if (this.warnLogger != null && this.warnLogger.isWarnEnabled()) {
this.warnLogger.warn(buildLogMessage(ex, request));
}
}
/**
* Build a log message for the given exception, occurred during processing the given request.
* @param ex the exception that got thrown during handler execution
* @param request current HTTP request (useful for obtaining metadata)
* @return the log message to use
*/
protected String buildLogMessage(Exception ex, HttpServletRequest request) {
return "Resolved exception caused by Handler execution: " + ex;
}
/**
* Prepare the response for the exceptional case.
* <p>The default implementation prevents the response from being cached,
* if the {@link #setPreventResponseCaching "preventResponseCaching"} property
* has been set to "true".
* @param ex the exception that got thrown during handler execution
* @param response current HTTP response
* @see #preventCaching
*/
protected void prepareResponse(Exception ex, HttpServletResponse response) {
if (this.preventResponseCaching) {
preventCaching(response);
}
}
/**
* Prevents the response from being cached, through setting corresponding
* HTTP {@code Cache-Control: no-store} header.
* @param response current HTTP response
*/
protected void preventCaching(HttpServletResponse response) {
response.addHeader(HEADER_CACHE_CONTROL, "no-store");
}
/**
* Actually resolve the given exception that got thrown during handler execution,
* returning a {@link ModelAndView} that represents a specific error page if appropriate.
* <p>May be overridden in subclasses, in order to apply specific exception checks.
* Note that this template method will be invoked <i>after</i> checking whether this
* resolved applies ("mappedHandlers" etc), so an implementation may simply proceed
* with its actual exception handling.
* @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 (for example, if multipart resolution failed)
* @param ex the exception that got thrown during handler execution
* @return a corresponding {@code ModelAndView} to forward to, or {@code null} for default processing
*/
protected abstract ModelAndView doResolveException(HttpServletRequest request,
HttpServletResponse response, Object handler, Exception ex);
}