Add CachingResourceResolver

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/CachingResourceResolver.java

@@ -0,0 +1,106 @@
+/*
+ * 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 org.springframework.cache.Cache;
+import org.springframework.core.io.Resource;
+import org.springframework.util.Assert;
+
+import javax.servlet.http.HttpServletRequest;
+import java.util.List;
+
+/**
+ * A {@link org.springframework.web.servlet.resource.ResourceResolver} that
+ * resolves resources from a {@link org.springframework.cache.Cache} or otherwise
+ * delegates to the resolver chain and saves the result in the cache.
+ *
+ * @author Rossen Stoyanchev
+ * @since 4.1
+ */
+public class CachingResourceResolver extends AbstractResourceResolver {
+
+	private static final String REQUEST_PATH_PREFIX = "requestPath:";
+
+	private static final String RESOURCE_URL_PATH_PREFIX = "resourceUrlPath:";
+
+
+	private final Cache cache;
+
+
+	public CachingResourceResolver(Cache cache) {
+		Assert.notNull(cache, "'cache' is required");
+		this.cache = cache;
+	}
+
+	/**
+	 * Return the configured {@code Cache}.
+	 */
+	public Cache getCache() {
+		return this.cache;
+	}
+
+	@Override
+	protected Resource resolveResourceInternal(HttpServletRequest request, String requestPath,
+			List<? extends Resource> locations, ResourceResolverChain chain) {
+
+		String key = REQUEST_PATH_PREFIX + requestPath;
+		Resource resource = this.cache.get(key, Resource.class);
+
+		if (resource != null) {
+			if (logger.isTraceEnabled()) {
+				logger.trace("Found match");
+			}
+			return resource;
+		}
+
+		resource = chain.resolveResource(request, requestPath, locations);
+		if (resource != null) {
+			if (logger.isTraceEnabled()) {
+				logger.trace("Putting resolved resource in cache");
+			}
+			this.cache.put(key, resource);
+		}
+
+		return resource;
+	}
+
+	@Override
+	protected String resolveUrlPathInternal(String resourceUrlPath,
+			List<? extends Resource> locations, ResourceResolverChain chain) {
+
+		String key = RESOURCE_URL_PATH_PREFIX + resourceUrlPath;
+		String resolvedUrlPath = this.cache.get(key, String.class);
+
+		if (resolvedUrlPath != null) {
+			if (logger.isTraceEnabled()) {
+				logger.trace("Found match");
+			}
+			return resolvedUrlPath;
+		}
+
+		resolvedUrlPath = chain.resolveUrlPath(resourceUrlPath, locations);
+		if (resolvedUrlPath != null) {
+			if (logger.isTraceEnabled()) {
+				logger.trace("Putting resolved resource URL path in cache");
+			}
+			this.cache.put(key, resolvedUrlPath);
+		}
+
+		return resolvedUrlPath;
+	}
+
+}

spring-webmvc/src/test/java/org/springframework/web/servlet/resource/CachingResourceResolverTests.java

@@ -0,0 +1,112 @@
+/*
+ * 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 org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mockito;
+import org.springframework.cache.Cache;
+import org.springframework.cache.concurrent.ConcurrentMapCache;
+import org.springframework.core.io.ClassPathResource;
+import org.springframework.core.io.Resource;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+
+/**
+ * Unit tests for
+ * {@link org.springframework.web.servlet.resource.CachingResourceResolver}.
+ *
+ * @author Rossen Stoyanchev
+ */
+public class CachingResourceResolverTests {
+
+	private Cache cache;
+
+	private ResourceResolverChain chain;
+
+	private List<Resource> locations;
+
+
+	@Before
+	public void setup() {
+
+		this.cache = new ConcurrentMapCache("resourceCache");
+
+		List<ResourceResolver> resolvers = new ArrayList<>();
+		resolvers.add(new CachingResourceResolver(this.cache));
+		resolvers.add(new PathResourceResolver());
+		this.chain = new DefaultResourceResolverChain(resolvers);
+
+		this.locations = new ArrayList<>();
+		this.locations.add(new ClassPathResource("test/", getClass()));
+	}
+
+
+	@Test
+	public void resolveResourceInternal() {
+		String file = "bar.css";
+		Resource expected = new ClassPathResource("test/" + file, getClass());
+		Resource actual = this.chain.resolveResource(null, file, this.locations);
+
+		assertEquals(expected, actual);
+	}
+
+	@Test
+	public void resolveResourceInternalFromCache() {
+
+		Resource expected = Mockito.mock(Resource.class);
+		this.cache.put("requestPath:bar.css", expected);
+
+		String file = "bar.css";
+		Resource actual = this.chain.resolveResource(null, file, this.locations);
+
+		assertSame(expected, actual);
+	}
+
+	@Test
+	public void resolveResourceInternalNoMatch() {
+		assertNull(this.chain.resolveResource(null, "invalid.css", this.locations));
+	}
+
+	@Test
+	public void resolverUrlPath() {
+		String expected = "/foo.css";
+		String actual = this.chain.resolveUrlPath(expected, this.locations);
+
+		assertEquals(expected, actual);
+	}
+
+	@Test
+	public void resolverUrlPathFromCache() {
+		String expected = "cached-imaginary.css";
+		this.cache.put("resourceUrlPath:imaginary.css", expected);
+		String actual = this.chain.resolveUrlPath("imaginary.css", this.locations);
+
+		assertEquals(expected, actual);
+	}
+
+	@Test
+	public void resolverUrlPathNoMatch() {
+		assertNull(this.chain.resolveUrlPath("invalid.css", this.locations));
+	}
+
+}