/*
* Copyright 2002-2012 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.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.util.ClassUtils;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.util.ReflectionUtils.MethodFilter;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.method.HandlerMethodSelector;
import org.springframework.web.servlet.HandlerMapping;
/**
* Abstract base class for {@link HandlerMapping} implementations that define a
* mapping between a request and a {@link HandlerMethod}.
*
* <p>For each registered handler method, a unique mapping is maintained with
* subclasses defining the details of the mapping type {@code <T>}.
*
* @param <T> The mapping for a {@link HandlerMethod} containing the conditions
* needed to match the handler method to incoming request.
*
* @author Arjen Poutsma
* @author Rossen Stoyanchev
* @since 3.1
*/
public abstract class AbstractHandlerMethodMapping<T> extends AbstractHandlerMapping implements InitializingBean {
private boolean detectHandlerMethodsInAncestorContexts = false;
private final Map<T, HandlerMethod> handlerMethods = new LinkedHashMap<T, HandlerMethod>();
private final MultiValueMap<String, T> urlMap = new LinkedMultiValueMap<String, T>();
/**
* Whether to detect handler methods in beans in ancestor ApplicationContexts.
* <p>Default is "false": Only beans in the current ApplicationContext are
* considered, i.e. only in the context that this HandlerMapping itself
* is defined in (typically the current DispatcherServlet's context).
* <p>Switch this flag on to detect handler beans in ancestor contexts
* (typically the Spring root WebApplicationContext) as well.
*/
public void setDetectHandlerMethodsInAncestorContexts(boolean detectHandlerMethodsInAncestorContexts) {
this.detectHandlerMethodsInAncestorContexts = detectHandlerMethodsInAncestorContexts;
}
/**
* Return a map with all handler methods and their mappings.
*/
public Map<T, HandlerMethod> getHandlerMethods() {
return Collections.unmodifiableMap(this.handlerMethods);
}
/**
* Detects handler methods at initialization.
*/
public void afterPropertiesSet() {
initHandlerMethods();
}
/**
* Scan beans in the ApplicationContext, detect and register handler methods.
* @see #isHandler(Class)
* @see #getMappingForMethod(Method, Class)
* @see #handlerMethodsInitialized(Map)
*/
protected void initHandlerMethods() {
if (logger.isDebugEnabled()) {
logger.debug("Looking for request mappings in application context: " + getApplicationContext());
}
String[] beanNames = (this.detectHandlerMethodsInAncestorContexts ?
BeanFactoryUtils.beanNamesForTypeIncludingAncestors(getApplicationContext(), Object.class) :
getApplicationContext().getBeanNamesForType(Object.class));
for (String beanName : beanNames) {
if (isHandler(getApplicationContext().getType(beanName))){
detectHandlerMethods(beanName);
}
}
handlerMethodsInitialized(getHandlerMethods());
}
/**
* Whether the given type is a handler with handler methods.
* @param beanType the type of the bean being checked
* @return "true" if this a handler type, "false" otherwise.
*/
protected abstract boolean isHandler(Class<?> beanType);
/**
* Invoked after all handler methods have been detected.
* @param handlerMethods a read-only map with handler methods and mappings.
*/
protected void handlerMethodsInitialized(Map<T, HandlerMethod> handlerMethods) {
}
/**
* Look for handler methods in a handler.
* @param handler the bean name of a handler or a handler instance
*/
protected void detectHandlerMethods(final Object handler) {
Class<?> handlerType = (handler instanceof String) ?
getApplicationContext().getType((String) handler) : handler.getClass();
final Class<?> userType = ClassUtils.getUserClass(handlerType);
Set<Method> methods = HandlerMethodSelector.selectMethods(userType, new MethodFilter() {
public boolean matches(Method method) {
return getMappingForMethod(method, userType) != null;
}
});
for (Method method : methods) {
T mapping = getMappingForMethod(method, userType);
registerHandlerMethod(handler, method, mapping);
}
}
/**
* Provide the mapping for a handler method. A method for which no
* mapping can be provided is not a handler method.
* @param method the method to provide a mapping for
* @param handlerType the handler type, possibly a sub-type of the method's
* declaring class
* @return the mapping, or {@code null} if the method is not mapped
*/
protected abstract T getMappingForMethod(Method method, Class<?> handlerType);
/**
* Register a handler method and its unique mapping.
* @param handler the bean name of the handler or the handler instance
* @param method the method to register
* @param mapping the mapping conditions associated with the handler method
* @throws IllegalStateException if another method was already registered
* under the same mapping
*/
protected void registerHandlerMethod(Object handler, Method method, T mapping) {
HandlerMethod handlerMethod;
if (handler instanceof String) {
String beanName = (String) handler;
handlerMethod = new HandlerMethod(beanName, getApplicationContext(), method);
}
else {
handlerMethod = new HandlerMethod(handler, method);
}
HandlerMethod oldHandlerMethod = handlerMethods.get(mapping);
if (oldHandlerMethod != null && !oldHandlerMethod.equals(handlerMethod)) {
throw new IllegalStateException("Ambiguous mapping found. Cannot map '" + handlerMethod.getBean()
+ "' bean method \n" + handlerMethod + "\nto " + mapping + ": There is already '"
+ oldHandlerMethod.getBean() + "' bean method\n" + oldHandlerMethod + " mapped.");
}
this.handlerMethods.put(mapping, handlerMethod);
if (logger.isInfoEnabled()) {
logger.info("Mapped \"" + mapping + "\" onto " + handlerMethod);
}
Set<String> patterns = getMappingPathPatterns(mapping);
for (String pattern : patterns) {
if (!getPathMatcher().isPattern(pattern)) {
this.urlMap.add(pattern, mapping);
}
}
}
/**
* Extract and return the URL paths contained in a mapping.
*/
protected abstract Set<String> getMappingPathPatterns(T mapping);
/**
* Look up a handler method for the given request.
*/
@Override
protected HandlerMethod getHandlerInternal(HttpServletRequest request) throws Exception {
String lookupPath = getUrlPathHelper().getLookupPathForRequest(request);
if (logger.isDebugEnabled()) {
logger.debug("Looking up handler method for path " + lookupPath);
}
HandlerMethod handlerMethod = lookupHandlerMethod(lookupPath, request);
if (logger.isDebugEnabled()) {
if (handlerMethod != null) {
logger.debug("Returning handler method [" + handlerMethod + "]");
}
else {
logger.debug("Did not find handler method for [" + lookupPath + "]");
}
}
return (handlerMethod != null) ? handlerMethod.createWithResolvedBean() : null;
}
/**
* Look up the best-matching handler method for the current request.
* If multiple matches are found, the best match is selected.
* @param lookupPath mapping lookup path within the current servlet mapping
* @param request the current request
* @return the best-matching handler method, or {@code null} if no match
* @see #handleMatch(Object, String, HttpServletRequest)
* @see #handleNoMatch(Set, String, HttpServletRequest)
*/
protected HandlerMethod lookupHandlerMethod(String lookupPath, HttpServletRequest request) throws Exception {
List<Match> matches = new ArrayList<Match>();
List<T> directPathMatches = this.urlMap.get(lookupPath);
if (directPathMatches != null) {
addMatchingMappings(directPathMatches, matches, request);
}
if (matches.isEmpty()) {
// No choice but to go through all mappings
addMatchingMappings(this.handlerMethods.keySet(), matches, request);
}
if (!matches.isEmpty()) {
Comparator<Match> comparator = new MatchComparator(getMappingComparator(request));
Collections.sort(matches, comparator);
if (logger.isTraceEnabled()) {
logger.trace("Found " + matches.size() + " matching mapping(s) for [" + lookupPath + "] : " + matches);
}
Match bestMatch = matches.get(0);
if (matches.size() > 1) {
Match secondBestMatch = matches.get(1);
if (comparator.compare(bestMatch, secondBestMatch) == 0) {
Method m1 = bestMatch.handlerMethod.getMethod();
Method m2 = secondBestMatch.handlerMethod.getMethod();
throw new IllegalStateException(
"Ambiguous handler methods mapped for HTTP path '" + request.getRequestURL() + "': {" +
m1 + ", " + m2 + "}");
}
}
handleMatch(bestMatch.mapping, lookupPath, request);
return bestMatch.handlerMethod;
}
else {
return handleNoMatch(handlerMethods.keySet(), lookupPath, request);
}
}
private void addMatchingMappings(Collection<T> mappings, List<Match> matches, HttpServletRequest request) {
for (T mapping : mappings) {
T match = getMatchingMapping(mapping, request);
if (match != null) {
matches.add(new Match(match, handlerMethods.get(mapping)));
}
}
}
/**
* Check if a mapping matches the current request and return a (potentially
* new) mapping with conditions relevant to the current request.
* @param mapping the mapping to get a match for
* @param request the current HTTP servlet request
* @return the match, or {@code null} if the mapping doesn't match
*/
protected abstract T getMatchingMapping(T mapping, HttpServletRequest request);
/**
* Return a comparator for sorting matching mappings.
* The returned comparator should sort 'better' matches higher.
* @param request the current request
* @return the comparator, never {@code null}
*/
protected abstract Comparator<T> getMappingComparator(HttpServletRequest request);
/**
* Invoked when a matching mapping is found.
* @param mapping the matching mapping
* @param lookupPath mapping lookup path within the current servlet mapping
* @param request the current request
*/
protected void handleMatch(T mapping, String lookupPath, HttpServletRequest request) {
request.setAttribute(HandlerMapping.PATH_WITHIN_HANDLER_MAPPING_ATTRIBUTE, lookupPath);
}
/**
* Invoked when no matching mapping is not found.
* @param mappings all registered mappings
* @param lookupPath mapping lookup path within the current servlet mapping
* @param request the current request
* @throws ServletException in case of errors
*/
protected HandlerMethod handleNoMatch(Set<T> mappings, String lookupPath, HttpServletRequest request)
throws Exception {
return null;
}
/**
* A temporary container for a mapping matched to a request.
*/
private class Match {
private final T mapping;
private final HandlerMethod handlerMethod;
private Match(T mapping, HandlerMethod handlerMethod) {
this.mapping = mapping;
this.handlerMethod = handlerMethod;
}
@Override
public String toString() {
return this.mapping.toString();
}
}
private class MatchComparator implements Comparator<Match> {
private final Comparator<T> comparator;
public MatchComparator(Comparator<T> comparator) {
this.comparator = comparator;
}
public int compare(Match match1, Match match2) {
return this.comparator.compare(match1.mapping, match2.mapping);
}
}
}