/*
* 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.Collections;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import javax.portlet.PortletException;
import javax.portlet.PortletRequest;
import org.springframework.beans.BeansException;
import org.springframework.util.Assert;
/**
* Abstract base class for {@link org.springframework.web.portlet.HandlerMapping}
* implementations that rely on a map which caches handler objects per lookup key.
* Supports arbitrary lookup keys, and automatically resolves handler bean names
* into handler bean instances.
*
* @author Juergen Hoeller
* @since 2.0
* @see #getLookupKey(javax.portlet.PortletRequest)
* @see #registerHandler(Object, Object)
*/
public abstract class AbstractMapBasedHandlerMapping<K> extends AbstractHandlerMapping {
private boolean lazyInitHandlers = false;
private final Map<K, Object> handlerMap = new HashMap<K, Object>();
/**
* Set whether to lazily initialize handlers. Only applicable to
* singleton handlers, as prototypes are always lazily initialized.
* Default is false, as eager initialization allows for more efficiency
* through referencing the handler objects directly.
* <p>If you want to allow your handlers to be lazily initialized,
* make them "lazy-init" and set this flag to true. Just making them
* "lazy-init" will not work, as they are initialized through the
* references from the handler mapping in this case.
*/
public void setLazyInitHandlers(boolean lazyInitHandlers) {
this.lazyInitHandlers = lazyInitHandlers;
}
/**
* Determines a handler for the computed lookup key for the given request.
* @see #getLookupKey
*/
@Override
@SuppressWarnings("unchecked")
protected Object getHandlerInternal(PortletRequest request) throws Exception {
K lookupKey = getLookupKey(request);
Object handler = this.handlerMap.get(lookupKey);
if (handler != null && logger.isDebugEnabled()) {
logger.debug("Key [" + lookupKey + "] -> handler [" + handler + "]");
}
if (handler instanceof Map) {
Map<PortletRequestMappingPredicate, Object> predicateMap =
(Map<PortletRequestMappingPredicate, Object>) handler;
List<PortletRequestMappingPredicate> predicates =
new LinkedList<PortletRequestMappingPredicate>(predicateMap.keySet());
Collections.sort(predicates);
for (PortletRequestMappingPredicate predicate : predicates) {
if (predicate.match(request)) {
predicate.validate(request);
return predicateMap.get(predicate);
}
}
return null;
}
return handler;
}
/**
* Build a lookup key for the given request.
* @param request current portlet request
* @return the lookup key (never <code>null</code>)
* @throws Exception if key computation failed
*/
protected abstract K getLookupKey(PortletRequest request) throws Exception;
/**
* Register all handlers specified in the Portlet mode map for the corresponding modes.
* @param handlerMap Map with lookup keys as keys and handler beans or bean names as values
* @throws BeansException if the handler couldn't be registered
*/
protected void registerHandlers(Map<K, ?> handlerMap) throws BeansException {
Assert.notNull(handlerMap, "Handler Map must not be null");
for (Map.Entry<K, ?> entry : handlerMap.entrySet()) {
registerHandler(entry.getKey(), entry.getValue());
}
}
/**
* Register the given handler instance for the given parameter value.
* @param lookupKey the key to map the handler onto
* @param handler the handler instance or handler bean name String
* (a bean name will automatically be resolved into the corresponding handler bean)
* @throws BeansException if the handler couldn't be registered
* @throws IllegalStateException if there is a conflicting handler registered
*/
protected void registerHandler(K lookupKey, Object handler) throws BeansException, IllegalStateException {
registerHandler(lookupKey, handler, null);
}
/**
* Register the given handler instance for the given parameter value.
* @param lookupKey the key to map the handler onto
* @param handler the handler instance or handler bean name String
* (a bean name will automatically be resolved into the corresponding handler bean)
* @param predicate a predicate object for this handler (may be <code>null</code>),
* determining a match with the primary lookup key
* @throws BeansException if the handler couldn't be registered
* @throws IllegalStateException if there is a conflicting handler registered
*/
@SuppressWarnings("unchecked")
protected void registerHandler(K lookupKey, Object handler, PortletRequestMappingPredicate predicate)
throws BeansException, IllegalStateException {
Assert.notNull(lookupKey, "Lookup key must not be null");
Assert.notNull(handler, "Handler object must not be null");
Object resolvedHandler = handler;
// Eagerly resolve handler if referencing singleton via name.
if (!this.lazyInitHandlers && handler instanceof String) {
String handlerName = (String) handler;
if (getApplicationContext().isSingleton(handlerName)) {
resolvedHandler = getApplicationContext().getBean(handlerName);
}
}
// Check for duplicate mapping.
Object mappedHandler = this.handlerMap.get(lookupKey);
if (mappedHandler != null && !(mappedHandler instanceof Map)) {
if (mappedHandler != resolvedHandler) {
throw new IllegalStateException("Cannot map handler [" + handler + "] to key [" + lookupKey +
"]: There's already handler [" + mappedHandler + "] mapped.");
}
}
else {
if (predicate != null) {
// Add the handler to the predicate map.
Map<PortletRequestMappingPredicate, Object> predicateMap =
(Map<PortletRequestMappingPredicate, Object>) mappedHandler;
if (predicateMap == null) {
predicateMap = new LinkedHashMap<PortletRequestMappingPredicate, Object>();
this.handlerMap.put(lookupKey, predicateMap);
}
predicateMap.put(predicate, resolvedHandler);
}
else {
// Add the single handler to the map.
this.handlerMap.put(lookupKey, resolvedHandler);
}
if (logger.isDebugEnabled()) {
logger.debug("Mapped key [" + lookupKey + "] onto handler [" + resolvedHandler + "]");
}
}
}
/**
* Predicate interface for determining a match with a given request.
*/
protected interface PortletRequestMappingPredicate extends Comparable {
/**
* Determine whether the given request matches this predicate.
* @param request current portlet request
*/
boolean match(PortletRequest request);
/**
* Validate this predicate's mapping against the current request.
* @param request current portlet request
* @throws PortletException if validation failed
*/
void validate(PortletRequest request) throws PortletException;
}
}
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