org.springframework.web.servlet.resource.ResourceTransformerSupport Maven / Gradle / Ivy
/*
* Copyright 2002-2018 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
*
* https://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.Collections;
import javax.servlet.http.HttpServletRequest;
import org.springframework.core.io.Resource;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
/**
* A base class for a {@code ResourceTransformer} with an optional helper method
* for resolving public links within a transformed resource.
*
* @author Brian Clozel
* @author Rossen Stoyanchev
* @author Juergen Hoeller
* @since 4.1
*/
public abstract class ResourceTransformerSupport implements ResourceTransformer {
@Nullable
private ResourceUrlProvider resourceUrlProvider;
/**
* Configure a {@link ResourceUrlProvider} to use when resolving the public
* URL of links in a transformed resource (e.g. import links in a CSS file).
* This is required only for links expressed as full paths and not for
* relative links.
*/
public void setResourceUrlProvider(@Nullable ResourceUrlProvider resourceUrlProvider) {
this.resourceUrlProvider = resourceUrlProvider;
}
/**
* Return the configured {@code ResourceUrlProvider}.
*/
@Nullable
public ResourceUrlProvider getResourceUrlProvider() {
return this.resourceUrlProvider;
}
/**
* A transformer can use this method when a resource being transformed
* contains links to other resources. Such links need to be replaced with the
* public facing link as determined by the resource resolver chain (e.g. the
* public URL may have a version inserted).
* @param resourcePath the path to a resource that needs to be re-written
* @param request the current request
* @param resource the resource being transformed
* @param transformerChain the transformer chain
* @return the resolved URL, or {@code} if not resolvable
*/
@Nullable
protected String resolveUrlPath(String resourcePath, HttpServletRequest request,
Resource resource, ResourceTransformerChain transformerChain) {
if (resourcePath.startsWith("/")) {
// full resource path
ResourceUrlProvider urlProvider = findResourceUrlProvider(request);
return (urlProvider != null ? urlProvider.getForRequestUrl(request, resourcePath) : null);
}
else {
// try resolving as relative path
return transformerChain.getResolverChain().resolveUrlPath(
resourcePath, Collections.singletonList(resource));
}
}
/**
* Transform the given relative request path to an absolute path,
* taking the path of the given request as a point of reference.
* The resulting path is also cleaned from sequences like "path/..".
* @param path the relative path to transform
* @param request the referer request
* @return the absolute request path for the given resource path
*/
protected String toAbsolutePath(String path, HttpServletRequest request) {
String absolutePath = path;
if (!path.startsWith("/")) {
ResourceUrlProvider urlProvider = findResourceUrlProvider(request);
Assert.state(urlProvider != null, "No ResourceUrlProvider");
String requestPath = urlProvider.getUrlPathHelper().getRequestUri(request);
absolutePath = StringUtils.applyRelativePath(requestPath, path);
}
return StringUtils.cleanPath(absolutePath);
}
@Nullable
private ResourceUrlProvider findResourceUrlProvider(HttpServletRequest request) {
if (this.resourceUrlProvider != null) {
return this.resourceUrlProvider;
}
return (ResourceUrlProvider) request.getAttribute(
ResourceUrlProviderExposingInterceptor.RESOURCE_URL_PROVIDER_ATTR);
}
}