/*
* Copyright 2002-2014 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.resource;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationListener;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.core.OrderComparator;
import org.springframework.util.AntPathMatcher;
import org.springframework.util.PathMatcher;
import org.springframework.web.servlet.handler.SimpleUrlHandlerMapping;
import org.springframework.web.util.UrlPathHelper;
/**
* A central component to use to obtain the public URL path that clients should
* use to access a static resource.
*
* <p>This class is aware of Spring MVC handler mappings used to serve static
* resources and uses the {@code ResourceResolver} chains of the configured
* {@code ResourceHttpRequestHandler}s to make its decisions.
*
* @author Rossen Stoyanchev
* @since 4.1
*/
public class ResourceUrlProvider implements ApplicationListener<ContextRefreshedEvent> {
protected final Log logger = LogFactory.getLog(getClass());
private UrlPathHelper pathHelper = new UrlPathHelper();
private PathMatcher pathMatcher = new AntPathMatcher();
private final Map<String, ResourceHttpRequestHandler> handlerMap = new HashMap<String, ResourceHttpRequestHandler>();
private boolean autodetect = true;
/**
* Configure a {@code UrlPathHelper} to use in
* {@link #getForRequestUrl(javax.servlet.http.HttpServletRequest, String)}
* in order to derive the lookup path for a target request URL path.
*/
public void setUrlPathHelper(UrlPathHelper pathHelper) {
this.pathHelper = pathHelper;
}
/**
* Return the configured {@code UrlPathHelper}.
*/
public UrlPathHelper getPathHelper() {
return this.pathHelper;
}
/**
* Configure a {@code PathMatcher} to use when comparing target lookup path
* against resource mappings.
*/
public void setPathMatcher(PathMatcher pathMatcher) {
this.pathMatcher = pathMatcher;
}
/**
* Return the configured {@code PathMatcher}.
*/
public PathMatcher getPathMatcher() {
return this.pathMatcher;
}
/**
* Manually configure the resource mappings.
* <p><strong>Note:</strong> by default resource mappings are auto-detected
* from the Spring {@code ApplicationContext}. However if this property is
* used, the auto-detection is turned off.
*/
public void setHandlerMap(Map<String, ResourceHttpRequestHandler> handlerMap) {
if (handlerMap != null) {
this.handlerMap.clear();
this.handlerMap.putAll(handlerMap);
this.autodetect = false;
}
}
/**
* Return the resource mappings, either manually configured or auto-detected
* when the Spring {@code ApplicationContext} is refreshed.
*/
public Map<String, ResourceHttpRequestHandler> getHandlerMap() {
return this.handlerMap;
}
/**
* Return {@code false} if resource mappings were manually configured,
* {@code true} otherwise.
*/
public boolean isAutodetect() {
return this.autodetect;
}
@Override
public void onApplicationEvent(ContextRefreshedEvent event) {
if (isAutodetect()) {
this.handlerMap.clear();
detectResourceHandlers(event.getApplicationContext());
if (this.handlerMap.isEmpty() && logger.isDebugEnabled()) {
logger.debug("No resource handling mappings found");
}
}
}
protected void detectResourceHandlers(ApplicationContext appContext) {
logger.debug("Looking for resource handler mappings");
Map<String, SimpleUrlHandlerMapping> map = appContext.getBeansOfType(SimpleUrlHandlerMapping.class);
List<SimpleUrlHandlerMapping> handlerMappings = new ArrayList<SimpleUrlHandlerMapping>(map.values());
Collections.sort(handlerMappings, new OrderComparator());
for (SimpleUrlHandlerMapping hm : handlerMappings) {
for (String pattern : hm.getHandlerMap().keySet()) {
Object handler = hm.getHandlerMap().get(pattern);
if (handler instanceof ResourceHttpRequestHandler) {
ResourceHttpRequestHandler resourceHandler = (ResourceHttpRequestHandler) handler;
if (logger.isDebugEnabled()) {
logger.debug("Found resource handler mapping: URL pattern=\"" + pattern + "\", " +
"locations=" + resourceHandler.getLocations() + ", " +
"resolvers=" + resourceHandler.getResourceResolvers());
}
this.handlerMap.put(pattern, resourceHandler);
}
}
}
}
/**
* A variation on {@link #getForLookupPath(String)} that accepts a full request
* URL path (i.e. including context and servlet path) and returns the full request
* URL path to expose for public use.
* @param request the current request
* @param requestUrl the request URL path to resolve
* @return the resolved public URL path or {@code null} if unresolved
*/
public final String getForRequestUrl(HttpServletRequest request, String requestUrl) {
if (logger.isTraceEnabled()) {
logger.trace("Getting resource URL for requestURL=" + requestUrl);
}
int index = getLookupPathIndex(request);
String prefix = requestUrl.substring(0, index);
String lookupPath = requestUrl.substring(index);
String resolvedLookupPath = getForLookupPath(lookupPath);
return (resolvedLookupPath != null) ? prefix + resolvedLookupPath : null;
}
private int getLookupPathIndex(HttpServletRequest request) {
String requestUri = getPathHelper().getRequestUri(request);
String lookupPath = getPathHelper().getLookupPathForRequest(request);
return requestUri.indexOf(lookupPath);
}
/**
* Compare the given path against configured resource handler mappings and
* if a match is found use the {@code ResourceResolver} chain of the matched
* {@code ResourceHttpRequestHandler} to resolve the URL path to expose for
* public use.
* <p>It is expected that the given path is what Spring MVC would use for
* request mapping purposes, i.e. excluding context and servlet path portions.
* @param lookupPath the lookup path to check
* @return the resolved public URL path, or {@code null} if unresolved
*/
public final String getForLookupPath(String lookupPath) {
if (logger.isTraceEnabled()) {
logger.trace("Getting resource URL for lookupPath=" + lookupPath);
}
for (String pattern : this.handlerMap.keySet()) {
if (!getPathMatcher().match(pattern, lookupPath)) {
continue;
}
String pathWithinMapping = getPathMatcher().extractPathWithinPattern(pattern, lookupPath);
String pathMapping = lookupPath.substring(0, lookupPath.indexOf(pathWithinMapping));
if (logger.isTraceEnabled()) {
logger.trace("Invoking ResourceResolverChain for URL pattern=\"" + pattern + "\"");
}
ResourceHttpRequestHandler handler = this.handlerMap.get(pattern);
ResourceResolverChain chain = new DefaultResourceResolverChain(handler.getResourceResolvers());
String resolved = chain.resolveUrlPath(pathWithinMapping, handler.getLocations());
if (resolved == null) {
throw new IllegalStateException("Failed to get public resource URL path for " + pathWithinMapping);
}
if (logger.isTraceEnabled()) {
logger.trace("Resolved public resource URL path=\"" + resolved + "\"");
}
return pathMapping + resolved;
}
logger.debug("No matching resource mapping");
return null;
}
}