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'databene commons' is an open source Java library by Volker Bergmann.
It provides extensions to the Java core library by utility classes, abstract concepts
and concrete implementations.
/*
* Copyright (C) 2004-2014 Volker Bergmann ([email protected]).
* All rights reserved.
*
* 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.databene.commons.web;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import org.databene.commons.IOUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Provides file download and caches files in the file system.
* Created: 15.08.2010 10:07:24
* @since 0.5.4
* @author Volker Bergmann
*/
public class DownloadCache {
private static final String DEFAULT_ROOT_FOLDER = "./cache";
private static final Logger LOGGER = LoggerFactory.getLogger(DownloadCache.class);
private File rootFolder;
public DownloadCache() {
this(new File(DEFAULT_ROOT_FOLDER));
}
public DownloadCache(File rootFolder) {
this.rootFolder = rootFolder;
}
public File get(URL url) throws IOException {
File cacheSubDir = new File(rootFolder, url.getHost());
String filename = url.getFile();
if (filename.endsWith("/"))
filename = filename.substring(0, filename.length() - 1) + ".dir";
File cacheFile = new File(cacheSubDir, filename);
if (!cacheFile.exists())
IOUtil.download(url, cacheFile);
else
LOGGER.info("providing {} from cache file {}", url, cacheFile.getAbsolutePath());
return cacheFile;
}
}