Add AppCacheResourceTransformer
This change adds a new ResourceTransformer that helps handling resources within HTML5 AppCache manifests for HTML5 offline application. This transformer: * modifies links to match the public URL paths * appends a comment in the manifest, containing a Hash (e.g. "# Hash: 9de0f09ed7caf84e885f1f0f11c7e326") See http://www.whatwg.org/specs/web-apps/current-work/multipage/offline.html#offline for more details on HTML5 offline apps and appcache manifests. Here is a WebConfig example: @Override public void addResourceHandlers(ResourceHandlerRegistry registry) { AppCacheResourceTransformer appCacheTransformer = new AppCacheResourceTransformer(); registry.addResourceHandler("/**") .addResourceLocations("classpath:static/") .setResourceResolvers(...) .setResourceTransformers(..., appCacheTransformer); } Issue: SPR-11964
This commit is contained in:
Brian Clozel
parent
2bd6e24b65
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f11815c960
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/*
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* Copyright 2002-2014 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.web.servlet.resource;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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import java.io.StringWriter;
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import java.nio.charset.Charset;
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import java.util.Arrays;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.Scanner;
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import javax.servlet.http.HttpServletRequest;
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import org.apache.commons.logging.Log;
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import org.apache.commons.logging.LogFactory;
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import org.springframework.core.io.Resource;
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import org.springframework.util.DigestUtils;
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import org.springframework.util.FileCopyUtils;
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import org.springframework.util.StringUtils;
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/**
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* A {@link ResourceTransformer} implementation that helps handling resources
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* within HTML5 AppCache manifests for HTML5 offline applications.
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*
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* <p>This transformer:
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* <ul>
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* <li>modifies links to match the public URL paths that should be exposed to clients, using
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* configured {@code ResourceResolver} strategies
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* <li>appends a comment in the manifest, containing a Hash (e.g. "# Hash: 9de0f09ed7caf84e885f1f0f11c7e326"),
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* thus changing the content of the manifest in order to trigger an appcache reload in the browser.
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* </ul>
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*
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* All files that have the ".manifest" file extension, or the extension given in the constructor, will be transformed
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* by this class.
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*
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* This hash is computed using the content of the appcache manifest and the content of the linked resources; so
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* changing a resource linked in the manifest or the manifest itself should invalidate browser cache.
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*
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* @author Brian Clozel
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* @see <a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/offline.html#offline">HTML5 offline
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* applications spec</a>
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* @since 4.1
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*/
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public class AppCacheResourceTransformer implements ResourceTransformer {
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private static final String MANIFEST_HEADER = "CACHE MANIFEST";
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private static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
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private static final Log logger = LogFactory.getLog(AppCacheResourceTransformer.class);
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private final Map<String, SectionTransformer> sectionTransformers = new HashMap<String, SectionTransformer>();
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private final String fileExtension;
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/**
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* Create an AppCacheResourceTransformer that transforms files with extension ".manifest"
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*/
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public AppCacheResourceTransformer() {
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this("manifest");
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}
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/**
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* Create an AppCacheResourceTransformer that transforms files with the extension
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* given as a parameter.
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*/
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public AppCacheResourceTransformer(String fileExtension) {
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this.fileExtension = fileExtension;
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SectionTransformer noOpSection = new NoOpSection();
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this.sectionTransformers.put(MANIFEST_HEADER, noOpSection);
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this.sectionTransformers.put("NETWORK:", noOpSection);
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this.sectionTransformers.put("FALLBACK:", noOpSection);
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this.sectionTransformers.put("CACHE:", new CacheSection());
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}
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@Override
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public Resource transform(HttpServletRequest request, Resource resource, ResourceTransformerChain transformerChain) throws IOException {
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resource = transformerChain.transform(request, resource);
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String filename = resource.getFilename();
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if (!this.fileExtension.equals(StringUtils.getFilenameExtension(filename))) {
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return resource;
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}
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byte[] bytes = FileCopyUtils.copyToByteArray(resource.getInputStream());
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String content = new String(bytes, DEFAULT_CHARSET);
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if(!content.startsWith(MANIFEST_HEADER)) {
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if (logger.isTraceEnabled()) {
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logger.trace("AppCache manifest does not start with 'CACHE MANIFEST', skipping: " + resource);
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}
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return resource;
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}
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if (logger.isTraceEnabled()) {
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logger.trace("Transforming resource: " + resource);
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}
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StringWriter contentWriter = new StringWriter();
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HashBuilder hashBuilder = new HashBuilder(content.length());
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Scanner scanner = new Scanner(content);
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SectionTransformer currentTransformer = this.sectionTransformers.get(MANIFEST_HEADER);
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while(scanner.hasNextLine()) {
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String line = scanner.nextLine();
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if(this.sectionTransformers.containsKey(line.trim())) {
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currentTransformer = this.sectionTransformers.get(line.trim());
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contentWriter.write(line + "\n");
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hashBuilder.appendString(line);
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}
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else {
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contentWriter.write(currentTransformer.transform(line, hashBuilder, resource, transformerChain) + "\n");
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}
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}
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String hash = hashBuilder.build();
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contentWriter.write("\n" + "# Hash: " + hash);
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if (logger.isTraceEnabled()) {
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logger.trace("AppCache file: [" + resource.getFilename()+ "] Hash: [" + hash + "]");
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}
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return new TransformedResource(resource, contentWriter.toString().getBytes(DEFAULT_CHARSET));
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}
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private static interface SectionTransformer {
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/**
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* Transforms a line in a section of the manifest
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*
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* The actual transformation depends on the chose transformation strategy
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* for the current manifest section (CACHE, NETWORK, FALLBACK, etc).
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*/
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String transform(String line, HashBuilder builder, Resource resource,
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ResourceTransformerChain transformerChain) throws IOException;
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}
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private static class NoOpSection implements SectionTransformer {
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public String transform(String line, HashBuilder builder,
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Resource resource, ResourceTransformerChain transformerChain) throws IOException {
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builder.appendString(line);
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return line;
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}
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}
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private static class CacheSection implements SectionTransformer {
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private final String COMMENT_DIRECTIVE = "#";
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@Override
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public String transform(String line, HashBuilder builder,
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Resource resource, ResourceTransformerChain transformerChain) throws IOException {
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if(isLink(line) && !hasScheme(line)) {
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Resource appCacheResource = transformerChain.getResolverChain().resolveResource(null, line, Arrays.asList(resource));
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String path = transformerChain.getResolverChain().resolveUrlPath(line, Arrays.asList(resource));
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builder.appendResource(appCacheResource);
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if (logger.isTraceEnabled()) {
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logger.trace("Link modified: " + path + " (original: " + line + ")");
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}
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return path;
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}
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builder.appendString(line);
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return line;
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}
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private boolean hasScheme(String link) {
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int schemeIndex = link.indexOf(":");
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return link.startsWith("//") || (schemeIndex > 0 && !link.substring(0, schemeIndex).contains("/"));
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}
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private boolean isLink(String line) {
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return StringUtils.hasText(line) && !line.startsWith(COMMENT_DIRECTIVE);
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}
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}
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private static class HashBuilder {
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private final ByteArrayOutputStream baos;
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private HashBuilder(int initialSize) {
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this.baos = new ByteArrayOutputStream(initialSize);
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}
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public void appendResource(Resource resource) throws IOException {
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byte[] content = FileCopyUtils.copyToByteArray(resource.getInputStream());
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this.baos.write(DigestUtils.md5Digest(content));
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}
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public void appendString(String content) throws IOException {
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this.baos.write(content.getBytes(DEFAULT_CHARSET));
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}
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public String build() {
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return DigestUtils.md5DigestAsHex(this.baos.toByteArray());
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}
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}
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}
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/*
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* Copyright 2002-2014 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.web.servlet.resource;
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import static org.junit.Assert.*;
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import static org.mockito.Mockito.*;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.List;
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import javax.servlet.http.HttpServletRequest;
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import org.hamcrest.Matchers;
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import org.junit.Before;
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import org.junit.Test;
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import org.springframework.core.io.ClassPathResource;
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import org.springframework.core.io.Resource;
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import org.springframework.util.FileCopyUtils;
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/**
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* Unit tests for
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* {@link org.springframework.web.servlet.resource.AppCacheResourceTransformer}.
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*
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* @author Brian Clozel
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*/
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public class AppCacheResourceTransformerTests {
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private AppCacheResourceTransformer transformer;
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private ResourceTransformerChain chain;
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private HttpServletRequest request;
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@Before
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public void setup() {
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this.transformer = new AppCacheResourceTransformer();
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this.chain = mock(ResourceTransformerChain.class);
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this.request = mock(HttpServletRequest.class);
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}
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@Test
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public void noTransformIfExtensionNoMatch() throws Exception {
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Resource resource = mock(Resource.class);
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when(resource.getFilename()).thenReturn("foobar.file");
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when(this.chain.transform(this.request, resource)).thenReturn(resource);
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Resource result = this.transformer.transform(this.request, resource, this.chain);
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assertEquals(resource, result);
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}
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@Test
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public void syntaxErrorInManifest() throws Exception {
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Resource resource = new ClassPathResource("test/error.manifest", getClass());
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when(this.chain.transform(this.request, resource)).thenReturn(resource);
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Resource result = this.transformer.transform(this.request, resource, this.chain);
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assertEquals(resource, result);
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}
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@Test
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public void transformManifest() throws Exception {
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VersionResourceResolver versionResourceResolver = new VersionResourceResolver();
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versionResourceResolver
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.setVersionStrategyMap(Collections.singletonMap("/**", new ContentBasedVersionStrategy()));
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List<ResourceResolver> resolvers = new ArrayList<ResourceResolver>();
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resolvers.add(versionResourceResolver);
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resolvers.add(new PathResourceResolver());
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ResourceResolverChain resolverChain = new DefaultResourceResolverChain(resolvers);
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List<ResourceTransformer> transformers = new ArrayList<>();
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transformers.add(new CssLinkResourceTransformer());
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this.chain = new DefaultResourceTransformerChain(resolverChain, transformers);
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Resource resource = new ClassPathResource("test/appcache.manifest", getClass());
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Resource result = this.transformer.transform(this.request, resource, this.chain);
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byte[] bytes = FileCopyUtils.copyToByteArray(result.getInputStream());
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String content = new String(bytes, "UTF-8");
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assertThat("should rewrite resource links", content,
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Matchers.containsString("foo-e36d2e05253c6c7085a91522ce43a0b4.css"));
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assertThat("should rewrite resource links", content,
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Matchers.containsString("bar-11e16cf79faee7ac698c805cf28248d2.css"));
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assertThat("should rewrite resource links", content,
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Matchers.containsString("js/bar-bd508c62235b832d960298ca6c0b7645.js"));
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assertThat("should not rewrite external resources", content,
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Matchers.containsString("//example.org/style.css"));
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assertThat("should not rewrite external resources", content,
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Matchers.containsString("http://example.org/image.png"));
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assertThat("should generate fingerprint", content,
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Matchers.containsString("# Hash: 4bf0338bcbeb0a5b3a4ec9ed8864107d"));
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}
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}
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@ -0,0 +1,17 @@
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CACHE MANIFEST
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# this is a comment
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CACHE:
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bar.css
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foo.css
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//example.org/style.css
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NETWORK:
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*
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CACHE:
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js/bar.js
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http://example.org/image.png
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FALLBACK:
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/main /static.html
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@ -0,0 +1,4 @@
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THIS DOES NOT START WITH "CACHE MANIFEST"
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CACHE:
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bar.css
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