org.databene.commons.web.DownloadCache Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of databene-commons Show documentation

'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.

The newest version!

/*
 * Copyright (C) 2004-2015 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;
	}

}