/*
* Copyright 2002-2008 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.portlet.handler;
import java.util.Enumeration;
import java.util.Properties;
import javax.portlet.MimeResponse;
import javax.portlet.PortletRequest;
import org.springframework.web.portlet.ModelAndView;
/**
* {@link org.springframework.web.portlet.HandlerExceptionResolver} implementation
* that allows for mapping exception class names to view names, either for a
* set of given handlers or for all handlers in the DispatcherPortlet.
*
* <p>Error views are analogous to error page JSPs, but can be used with any
* kind of exception including any checked one, with fine-granular mappings for
* specific handlers.
*
* @author Juergen Hoeller
* @author John A. Lewis
* @author Arjen Poutsma
* @since 2.0
*/
public class SimpleMappingExceptionResolver extends AbstractHandlerExceptionResolver {
/**
* The default name of the exception attribute: "exception".
*/
public static final String DEFAULT_EXCEPTION_ATTRIBUTE = "exception";
private Properties exceptionMappings;
private String defaultErrorView;
private String exceptionAttribute = DEFAULT_EXCEPTION_ATTRIBUTE;
/**
* Set the mappings between exception class names and error view names.
* The exception class name can be a substring, with no wildcard support
* at present. A value of "PortletException" would match
* <code>javax.portet.PortletException</code> and subclasses, for example.
* <p><b>NB:</b> Consider carefully how specific the pattern is, and whether
* to include package information (which isn't mandatory). For example,
* "Exception" will match nearly anything, and will probably hide other rules.
* "java.lang.Exception" would be correct if "Exception" was meant to define
* a rule for all checked exceptions. With more unusual exception names such
* as "BaseBusinessException" there's no need to use a FQN.
* <p>Follows the same matching algorithm as RuleBasedTransactionAttribute
* and RollbackRuleAttribute.
* @param mappings exception patterns (can also be fully qualified class names)
* as keys, and error view names as values
* @see org.springframework.transaction.interceptor.RuleBasedTransactionAttribute
* @see org.springframework.transaction.interceptor.RollbackRuleAttribute
*/
public void setExceptionMappings(Properties mappings) {
this.exceptionMappings = mappings;
}
/**
* Set the name of the default error view.
* This view will be returned if no specific mapping was found.
* <p>Default is none.
*/
public void setDefaultErrorView(String defaultErrorView) {
this.defaultErrorView = defaultErrorView;
}
/**
* Set the name of the model attribute as which the exception should
* be exposed. Default is "exception".
* @see #DEFAULT_EXCEPTION_ATTRIBUTE
*/
public void setExceptionAttribute(String exceptionAttribute) {
this.exceptionAttribute = exceptionAttribute;
}
/**
* Actually resolve the given exception that got thrown during on handler execution,
* returning a ModelAndView that represents a specific error page if appropriate.
* @param request current portlet request
* @param response current portlet response
* @param handler the executed handler, or 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 ModelAndView to forward to, or null for default processing
*/
@Override
protected ModelAndView doResolveException(
PortletRequest request, MimeResponse response, Object handler, Exception ex) {
// Log exception, both at debug log level and at warn level, if desired.
if (logger.isDebugEnabled()) {
logger.debug("Resolving exception from handler [" + handler + "]: " + ex);
}
logException(ex, request);
// Expose ModelAndView for chosen error view.
String viewName = determineViewName(ex, request);
if (viewName != null) {
return getModelAndView(viewName, ex, request);
}
else {
return null;
}
}
/**
* Determine the view name for the given exception, searching the
* {@link #setExceptionMappings "exceptionMappings"}, using the
* {@link #setDefaultErrorView "defaultErrorView"} as fallback.
* @param ex the exception that got thrown during handler execution
* @param request current portlet request (useful for obtaining metadata)
* @return the resolved view name, or <code>null</code> if none found
*/
protected String determineViewName(Exception ex, PortletRequest request) {
String viewName = null;
// Check for specific exception mappings.
if (this.exceptionMappings != null) {
viewName = findMatchingViewName(this.exceptionMappings, ex);
}
// Return default error view else, if defined.
if (viewName == null && this.defaultErrorView != null) {
if (logger.isDebugEnabled()) {
logger.debug("Resolving to default view '" + this.defaultErrorView +
"' for exception of type [" + ex.getClass().getName() + "]");
}
viewName = this.defaultErrorView;
}
return viewName;
}
/**
* Find a matching view name in the given exception mappings
* @param exceptionMappings mappings between exception class names and error view names
* @param ex the exception that got thrown during handler execution
* @return the view name, or <code>null</code> if none found
* @see #setExceptionMappings
*/
protected String findMatchingViewName(Properties exceptionMappings, Exception ex) {
String viewName = null;
String dominantMapping = null;
int deepest = Integer.MAX_VALUE;
for (Enumeration names = exceptionMappings.propertyNames(); names.hasMoreElements();) {
String exceptionMapping = (String) names.nextElement();
int depth = getDepth(exceptionMapping, ex);
if (depth >= 0 && depth < deepest) {
deepest = depth;
dominantMapping = exceptionMapping;
viewName = exceptionMappings.getProperty(exceptionMapping);
}
}
if (viewName != null && logger.isDebugEnabled()) {
logger.debug("Resolving to view '" + viewName + "' for exception of type [" + ex.getClass().getName() +
"], based on exception mapping [" + dominantMapping + "]");
}
return viewName;
}
/**
* Return the depth to the superclass matching.
* <p>0 means ex matches exactly. Returns -1 if there's no match.
* Otherwise, returns depth. Lowest depth wins.
* <p>Follows the same algorithm as
* {@link org.springframework.transaction.interceptor.RollbackRuleAttribute}.
*/
protected int getDepth(String exceptionMapping, Exception ex) {
return getDepth(exceptionMapping, ex.getClass(), 0);
}
private int getDepth(String exceptionMapping, Class exceptionClass, int depth) {
if (exceptionClass.getName().contains(exceptionMapping)) {
// Found it!
return depth;
}
// If we've gone as far as we can go and haven't found it...
if (exceptionClass.equals(Throwable.class)) {
return -1;
}
return getDepth(exceptionMapping, exceptionClass.getSuperclass(), depth + 1);
}
/**
* Return a ModelAndView for the given request, view name and exception.
* Default implementation delegates to <code>getModelAndView(viewName, ex)</code>.
* @param viewName the name of the error view
* @param ex the exception that got thrown during handler execution
* @param request current portlet request (useful for obtaining metadata)
* @return the ModelAndView instance
* @see #getModelAndView(String, Exception)
*/
protected ModelAndView getModelAndView(String viewName, Exception ex, PortletRequest request) {
return getModelAndView(viewName, ex);
}
/**
* Return a ModelAndView for the given view name and exception.
* Default implementation adds the specified exception attribute.
* Can be overridden in subclasses.
* @param viewName the name of the error view
* @param ex the exception that got thrown during handler execution
* @return the ModelAndView instance
* @see #setExceptionAttribute
*/
protected ModelAndView getModelAndView(String viewName, Exception ex) {
ModelAndView mv = new ModelAndView(viewName);
if (this.exceptionAttribute != null) {
if (logger.isDebugEnabled()) {
logger.debug("Exposing Exception as model attribute '" + this.exceptionAttribute + "'");
}
mv.addObject(this.exceptionAttribute, ex);
}
return mv;
}
}
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