/*
* Copyright 2002-2017 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.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.URI;
import java.net.URL;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import org.springframework.core.io.AbstractResource;
import org.springframework.core.io.Resource;
import org.springframework.http.HttpHeaders;
import org.springframework.util.AntPathMatcher;
import org.springframework.util.StringUtils;
/**
* Resolves request paths containing a version string that can be used as part
* of an HTTP caching strategy in which a resource is cached with a date in the
* distant future (e.g. 1 year) and cached until the version, and therefore the
* URL, is changed.
*
* <p>Different versioning strategies exist, and this resolver must be configured
* with one or more such strategies along with path mappings to indicate which
* strategy applies to which resources.
*
* <p>{@code ContentVersionStrategy} is a good default choice except in cases
* where it cannot be used. Most notably the {@code ContentVersionStrategy}
* cannot be combined with JavaScript module loaders. For such cases the
* {@code FixedVersionStrategy} is a better choice.
*
* <p>Note that using this resolver to serve CSS files means that the
* {@link CssLinkResourceTransformer} should also be used in order to modify
* links within CSS files to also contain the appropriate versions generated
* by this resolver.
*
* @author Brian Clozel
* @author Rossen Stoyanchev
* @since 4.1
* @see VersionStrategy
*/
public class VersionResourceResolver extends AbstractResourceResolver {
private AntPathMatcher pathMatcher = new AntPathMatcher();
/** Map from path pattern -> VersionStrategy */
private final Map<String, VersionStrategy> versionStrategyMap = new LinkedHashMap<>();
/**
* Set a Map with URL paths as keys and {@code VersionStrategy} as values.
* <p>Supports direct URL matches and Ant-style pattern matches. For syntax
* details, see the {@link org.springframework.util.AntPathMatcher} javadoc.
* @param map map with URLs as keys and version strategies as values
*/
public void setStrategyMap(Map<String, VersionStrategy> map) {
this.versionStrategyMap.clear();
this.versionStrategyMap.putAll(map);
}
/**
* Return the map with version strategies keyed by path pattern.
*/
public Map<String, VersionStrategy> getStrategyMap() {
return this.versionStrategyMap;
}
/**
* Insert a content-based version in resource URLs that match the given path
* patterns. The version is computed from the content of the file, e.g.
* {@code "css/main-e36d2e05253c6c7085a91522ce43a0b4.css"}. This is a good
* default strategy to use except when it cannot be, for example when using
* JavaScript module loaders, use {@link #addFixedVersionStrategy} instead
* for serving JavaScript files.
* @param pathPatterns one or more resource URL path patterns,
* relative to the pattern configured with the resource handler
* @return the current instance for chained method invocation
* @see ContentVersionStrategy
*/
public VersionResourceResolver addContentVersionStrategy(String... pathPatterns) {
addVersionStrategy(new ContentVersionStrategy(), pathPatterns);
return this;
}
/**
* Insert a fixed, prefix-based version in resource URLs that match the given
* path patterns, for example: <code>"{version}/js/main.js"</code>. This is useful (vs.
* content-based versions) when using JavaScript module loaders.
* <p>The version may be a random number, the current date, or a value
* fetched from a git commit sha, a property file, or environment variable
* and set with SpEL expressions in the configuration (e.g. see {@code @Value}
* in Java config).
* <p>If not done already, variants of the given {@code pathPatterns}, prefixed with
* the {@code version} will be also configured. For example, adding a {@code "/js/**"} path pattern
* will also cofigure automatically a {@code "/v1.0.0/js/**"} with {@code "v1.0.0"} the
* {@code version} String given as an argument.
* @param version a version string
* @param pathPatterns one or more resource URL path patterns,
* relative to the pattern configured with the resource handler
* @return the current instance for chained method invocation
* @see FixedVersionStrategy
*/
public VersionResourceResolver addFixedVersionStrategy(String version, String... pathPatterns) {
List<String> patternsList = Arrays.asList(pathPatterns);
List<String> prefixedPatterns = new ArrayList<>(pathPatterns.length);
String versionPrefix = "/" + version;
for (String pattern : patternsList) {
prefixedPatterns.add(pattern);
if (!pattern.startsWith(versionPrefix) && !patternsList.contains(versionPrefix + pattern)) {
prefixedPatterns.add(versionPrefix + pattern);
}
}
return addVersionStrategy(new FixedVersionStrategy(version), prefixedPatterns.toArray(new String[0]));
}
/**
* Register a custom VersionStrategy to apply to resource URLs that match the
* given path patterns.
* @param strategy the custom strategy
* @param pathPatterns one or more resource URL path patterns,
* relative to the pattern configured with the resource handler
* @return the current instance for chained method invocation
* @see VersionStrategy
*/
public VersionResourceResolver addVersionStrategy(VersionStrategy strategy, String... pathPatterns) {
for (String pattern : pathPatterns) {
getStrategyMap().put(pattern, strategy);
}
return this;
}
@Override
protected Resource resolveResourceInternal(HttpServletRequest request, String requestPath,
List<? extends Resource> locations, ResourceResolverChain chain) {
Resource resolved = chain.resolveResource(request, requestPath, locations);
if (resolved != null) {
return resolved;
}
VersionStrategy versionStrategy = getStrategyForPath(requestPath);
if (versionStrategy == null) {
return null;
}
String candidateVersion = versionStrategy.extractVersion(requestPath);
if (StringUtils.isEmpty(candidateVersion)) {
if (logger.isTraceEnabled()) {
logger.trace("No version found in path \"" + requestPath + "\"");
}
return null;
}
String simplePath = versionStrategy.removeVersion(requestPath, candidateVersion);
if (logger.isTraceEnabled()) {
logger.trace("Extracted version from path, re-resolving without version: \"" + simplePath + "\"");
}
Resource baseResource = chain.resolveResource(request, simplePath, locations);
if (baseResource == null) {
return null;
}
String actualVersion = versionStrategy.getResourceVersion(baseResource);
if (candidateVersion.equals(actualVersion)) {
if (logger.isTraceEnabled()) {
logger.trace("Resource matches extracted version [" + candidateVersion + "]");
}
return new FileNameVersionedResource(baseResource, candidateVersion);
}
else {
if (logger.isTraceEnabled()) {
logger.trace("Potential resource found for \"" + requestPath + "\", but version [" +
candidateVersion + "] does not match");
}
return null;
}
}
@Override
protected String resolveUrlPathInternal(String resourceUrlPath, List<? extends Resource> locations, ResourceResolverChain chain) {
String baseUrl = chain.resolveUrlPath(resourceUrlPath, locations);
if (StringUtils.hasText(baseUrl)) {
VersionStrategy versionStrategy = getStrategyForPath(resourceUrlPath);
if (versionStrategy == null) {
return baseUrl;
}
if (logger.isTraceEnabled()) {
logger.trace("Getting the original resource to determine version for path \"" + resourceUrlPath + "\"");
}
Resource resource = chain.resolveResource(null, baseUrl, locations);
String version = versionStrategy.getResourceVersion(resource);
if (logger.isTraceEnabled()) {
logger.trace("Determined version [" + version + "] for " + resource);
}
return versionStrategy.addVersion(baseUrl, version);
}
return baseUrl;
}
/**
* Find a {@code VersionStrategy} for the request path of the requested resource.
* @return an instance of a {@code VersionStrategy} or null if none matches that request path
*/
protected VersionStrategy getStrategyForPath(String requestPath) {
String path = "/".concat(requestPath);
List<String> matchingPatterns = new ArrayList<>();
for (String pattern : this.versionStrategyMap.keySet()) {
if (this.pathMatcher.match(pattern, path)) {
matchingPatterns.add(pattern);
}
}
if (!matchingPatterns.isEmpty()) {
Comparator<String> comparator = this.pathMatcher.getPatternComparator(path);
Collections.sort(matchingPatterns, comparator);
return this.versionStrategyMap.get(matchingPatterns.get(0));
}
return null;
}
private class FileNameVersionedResource extends AbstractResource implements HttpResource {
private final Resource original;
private final String version;
public FileNameVersionedResource(Resource original, String version) {
this.original = original;
this.version = version;
}
@Override
public boolean exists() {
return this.original.exists();
}
@Override
public boolean isReadable() {
return this.original.isReadable();
}
@Override
public boolean isOpen() {
return this.original.isOpen();
}
@Override
public boolean isFile() {
return this.original.isFile();
}
@Override
public URL getURL() throws IOException {
return this.original.getURL();
}
@Override
public URI getURI() throws IOException {
return this.original.getURI();
}
@Override
public File getFile() throws IOException {
return this.original.getFile();
}
@Override
public String getFilename() {
return this.original.getFilename();
}
@Override
public long contentLength() throws IOException {
return this.original.contentLength();
}
@Override
public long lastModified() throws IOException {
return this.original.lastModified();
}
@Override
public Resource createRelative(String relativePath) throws IOException {
return this.original.createRelative(relativePath);
}
@Override
public String getDescription() {
return original.getDescription();
}
@Override
public InputStream getInputStream() throws IOException {
return original.getInputStream();
}
@Override
public HttpHeaders getResponseHeaders() {
HttpHeaders headers;
if(this.original instanceof HttpResource) {
headers = ((HttpResource) this.original).getResponseHeaders();
}
else {
headers = new HttpHeaders();
}
headers.setETag("\"" + this.version + "\"");
return headers;
}
}
}