org.springframework.web.servlet.resource.ContentVersionStrategy 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.io.IOException;
import org.springframework.core.io.Resource;
import org.springframework.util.DigestUtils;
import org.springframework.util.FileCopyUtils;
/**
* A {@code VersionStrategy} that calculates a Hex MD5 hash from the content
* of the resource and appends it to the file name, e.g.
* {@code "styles/main-e36d2e05253c6c7085a91522ce43a0b4.css"}.
*
* @author Brian Clozel
* @author Rossen Stoyanchev
* @since 4.1
* @see VersionResourceResolver
*/
public class ContentVersionStrategy extends AbstractVersionStrategy {
public ContentVersionStrategy() {
super(new FileNameVersionPathStrategy());
}
@Override
public String getResourceVersion(Resource resource) {
try {
byte[] content = FileCopyUtils.copyToByteArray(resource.getInputStream());
return DigestUtils.md5DigestAsHex(content);
}
catch (IOException ex) {
throw new IllegalStateException("Failed to calculate hash for " + resource, ex);
}
}
}