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* $Id$
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.struts.config;
import java.lang.reflect.InvocationTargetException;
/**
* A JavaBean representing the configuration information of an
* <exception> element from a Struts configuration
* file.
*
* @version $Rev$ $Date: 2005-08-06 18:03:30 -0400 (Sat, 06 Aug 2005)
* $
* @since Struts 1.1
*/
public class ExceptionConfig extends BaseConfig {
private static final long serialVersionUID = -6269406361939618377L;
// ------------------------------------------------------------- Properties
/**
* The servlet context attribute under which the message resources bundle
* to be used for this exception is located. If not set, the default
* message resources for the current module is assumed.
*/
protected String bundle = null;
/**
* The type of the ExceptionConfig that this object should inherit
* properties from.
*/
protected String inherit = null;
/**
* Have the inheritance values for this class been applied?
*/
protected boolean extensionProcessed = false;
/**
* The fully qualified Java class name of the exception handler class
* which should be instantiated to handle this exception.
*/
protected String handler = "org.apache.struts.action.ExceptionHandler";
/**
* The message resources key specifying the error message associated with
* this exception.
*/
protected String key = null;
/**
* The module-relative path of the resource to forward to if this
* exception occurs during an Action.
*/
protected String path = null;
/**
* The scope in which we should expose the ActionMessage for this
* exception handler.
*/
protected String scope = "request";
/**
* The fully qualified Java class name of the exception that is to be
* handled by this handler.
*/
protected String type = null;
public String getBundle() {
return (this.bundle);
}
public void setBundle(String bundle) {
if (configured) {
throw new IllegalStateException("Configuration is frozen");
}
this.bundle = bundle;
}
public String getExtends() {
return (this.inherit);
}
public void setExtends(String inherit) {
if (configured) {
throw new IllegalStateException("Configuration is frozen");
}
this.inherit = inherit;
}
public boolean isExtensionProcessed() {
return extensionProcessed;
}
public String getHandler() {
return (this.handler);
}
public void setHandler(String handler) {
if (configured) {
throw new IllegalStateException("Configuration is frozen");
}
this.handler = handler;
}
public String getKey() {
return (this.key);
}
public void setKey(String key) {
if (configured) {
throw new IllegalStateException("Configuration is frozen");
}
this.key = key;
}
public String getPath() {
return (this.path);
}
public void setPath(String path) {
if (configured) {
throw new IllegalStateException("Configuration is frozen");
}
this.path = path;
}
public String getScope() {
return (this.scope);
}
public void setScope(String scope) {
if (configured) {
throw new IllegalStateException("Configuration is frozen");
}
this.scope = scope;
}
public String getType() {
return (this.type);
}
public void setType(String type) {
if (configured) {
throw new IllegalStateException("Configuration is frozen");
}
this.type = type;
}
// ------------------------------------------------------ Protected Methods
/**
* Traces the hierarchy of this object to check if any of the ancestors
* are extending this instance.
*
* @param moduleConfig The {@link ModuleConfig} that this config is from.
* @param actionConfig The {@link ActionConfig} that this config is from,
* if applicable. This parameter must be null if this
* is a global handler.
* @return true if circular inheritance was detected.
*/
protected boolean checkCircularInheritance(ModuleConfig moduleConfig,
ActionConfig actionConfig) {
String ancestorType = getExtends();
if (ancestorType == null) {
return false;
}
// Find our ancestor
ExceptionConfig ancestor = null;
// First check the action config
if (actionConfig != null) {
ancestor = actionConfig.findExceptionConfig(ancestorType);
// If we found *this*, set ancestor to null to check for a global def
if (ancestor == this) {
ancestor = null;
}
}
// Then check the global handlers
if (ancestor == null) {
ancestor = moduleConfig.findExceptionConfig(ancestorType);
if (ancestor != null) {
// If the ancestor is a global handler, set actionConfig
// to null so further searches are only done among
// global handlers.
actionConfig = null;
}
}
while (ancestor != null) {
// Check if an ancestor is extending *this*
if (ancestor == this) {
return true;
}
// Get our ancestor's ancestor
ancestorType = ancestor.getExtends();
// check against ancestors extending same typed ancestors
if (ancestor.getType().equals(ancestorType)) {
// If the ancestor is extending a config for the same type,
// make sure we look for its ancestor in the global handlers.
// If we're already at that level, we return false.
if (actionConfig == null) {
return false;
} else {
// Set actionConfig = null to force us to look for global
// forwards
actionConfig = null;
}
}
ancestor = null;
// First check the action config
if (actionConfig != null) {
ancestor = actionConfig.findExceptionConfig(ancestorType);
}
// Then check the global handlers
if (ancestor == null) {
ancestor = moduleConfig.findExceptionConfig(ancestorType);
if (ancestor != null) {
// Limit further checks to moduleConfig.
actionConfig = null;
}
}
}
return false;
}
// --------------------------------------------------------- Public Methods
/**
* Inherit values that have not been overridden from the provided
* config object. Subclasses overriding this method should verify that
* the given parameter is of a class that contains a property it is trying
* to inherit:
*
*
* if (config instanceof MyCustomConfig) {
* MyCustomConfig myConfig =
* (MyCustomConfig) config;
*
* if (getMyCustomProp() == null) {
* setMyCustomProp(myConfig.getMyCustomProp());
* }
* }
*
*
* If the given config is extending another object, those
* extensions should be resolved before it's used as a parameter to this
* method.
*
* @param config The object that this instance will be inheriting its
* values from.
* @see #processExtends(ModuleConfig, ActionConfig)
*/
public void inheritFrom(ExceptionConfig config)
throws ClassNotFoundException, IllegalAccessException,
InstantiationException, InvocationTargetException {
if (configured) {
throw new IllegalStateException("Configuration is frozen");
}
// Inherit values that have not been overridden
if (getBundle() == null) {
setBundle(config.getBundle());
}
if (getHandler().equals("org.apache.struts.action.ExceptionHandler")) {
setHandler(config.getHandler());
}
if (getKey() == null) {
setKey(config.getKey());
}
if (getPath() == null) {
setPath(config.getPath());
}
if (getScope().equals("request")) {
setScope(config.getScope());
}
if (getType() == null) {
setType(config.getType());
}
inheritProperties(config);
}
/**
* Inherit configuration information from the ExceptionConfig that this
* instance is extending. This method verifies that any exception config
* object that it inherits from has also had its processExtends() method
* called.
*
* @param moduleConfig The {@link ModuleConfig} that this config is from.
* @param actionConfig The {@link ActionConfig} that this config is from,
* if applicable. This must be null for global
* forwards.
* @see #inheritFrom(ExceptionConfig)
*/
public void processExtends(ModuleConfig moduleConfig,
ActionConfig actionConfig)
throws ClassNotFoundException, IllegalAccessException,
InstantiationException, InvocationTargetException {
if (configured) {
throw new IllegalStateException("Configuration is frozen");
}
String ancestorType = getExtends();
if ((!extensionProcessed) && (ancestorType != null)) {
ExceptionConfig baseConfig = null;
// We only check the action config if we're not a global handler
boolean checkActionConfig =
(this != moduleConfig.findExceptionConfig(getType()));
// ... and the action config was provided
checkActionConfig &= (actionConfig != null);
// ... and we're not extending a config with the same type value
// (because if we are, that means we're an action-level handler
// extending a global handler).
checkActionConfig &= !ancestorType.equals(getType());
// We first check in the action config's exception handlers
if (checkActionConfig) {
baseConfig = actionConfig.findExceptionConfig(ancestorType);
}
// Then check the global exception handlers
if (baseConfig == null) {
baseConfig = moduleConfig.findExceptionConfig(ancestorType);
}
if (baseConfig == null) {
throw new NullPointerException("Unable to find "
+ "handler for '" + ancestorType + "' to extend.");
}
// Check for circular inheritance and make sure the base config's
// own inheritance has been processed already
if (checkCircularInheritance(moduleConfig, actionConfig)) {
throw new IllegalArgumentException(
"Circular inheritance detected for forward " + getType());
}
if (!baseConfig.isExtensionProcessed()) {
baseConfig.processExtends(moduleConfig, actionConfig);
}
// copy values from the base config
inheritFrom(baseConfig);
}
extensionProcessed = true;
}
/**
* Return a String representation of this object.
*/
public String toString() {
StringBuilder sb = new StringBuilder("ExceptionConfig[");
sb.append("type=");
sb.append(this.type);
if (this.bundle != null) {
sb.append(",bundle=");
sb.append(this.bundle);
}
if (this.inherit != null) {
sb.append(",extends=");
sb.append(this.inherit);
}
sb.append(",handler=");
sb.append(this.handler);
sb.append(",key=");
sb.append(this.key);
sb.append(",path=");
sb.append(this.path);
sb.append(",scope=");
sb.append(this.scope);
sb.append("]");
return (sb.toString());
}
}