rome/src/main/java/com/rometools/fetcher/impl/DiskFeedInfoCache.java
2015-02-16 22:25:26 +01:00

158 lines
4.3 KiB
Java

/*
* Copyright 2005 Sun Microsystems, Inc.
*
* 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 com.rometools.fetcher.impl;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.URL;
import com.rometools.utils.IO;
/**
* Disk based feed cache.
*/
public class DiskFeedInfoCache implements FeedFetcherCache {
protected String cachePath = null;
public DiskFeedInfoCache(final String cachePath) {
this.cachePath = cachePath;
}
@Override
public SyndFeedInfo getFeedInfo(final URL url) {
final String fileName = generateFilename(url);
return getFeedInfo(fileName);
}
@Override
public void setFeedInfo(final URL url, final SyndFeedInfo feedInfo) {
final String fileName = generateFilename(url);
FileOutputStream fos = null;
ObjectOutputStream oos = null;
try {
fos = new FileOutputStream(fileName);
oos = new ObjectOutputStream(fos);
oos.writeObject(feedInfo);
fos.flush();
} catch (final FileNotFoundException e) {
throw new RuntimeException("Error while writing to cache", e);
} catch (final IOException e) {
throw new RuntimeException("Error while writing to cache", e);
} finally {
IO.closeQuietly(fos);
IO.closeQuietly(oos);
}
}
@Override
public synchronized void clear() {
final File file = new File(cachePath);
// only do the delete if the directory exists
if (file.exists() && file.canWrite()) {
// make the directory empty
final String[] files = file.list();
final int len = files.length;
for (int i = 0; i < len; i++) {
final File deleteMe = new File(cachePath + File.separator + files[i]);
deleteMe.delete();
}
// don't delete the cache directory
}
}
@Override
public SyndFeedInfo remove(final URL url) {
final String fileName = generateFilename(url);
final SyndFeedInfo info = getFeedInfo(fileName);
if (info != null) {
final File file = new File(fileName);
if (file.exists()) {
file.delete();
}
}
return info;
}
private SyndFeedInfo getFeedInfo(final String fileName) {
SyndFeedInfo info = null;
FileInputStream fis = null;
ObjectInputStream ois = null;
try {
fis = new FileInputStream(fileName);
ois = new ObjectInputStream(fis);
info = (SyndFeedInfo) ois.readObject();
} catch (final FileNotFoundException e) {
// feed is not cached yet
} catch (final ClassNotFoundException e) {
throw new RuntimeException("Unable to read from cache", e);
} catch (final IOException e) {
throw new RuntimeException("Unable to read from cache", e);
} finally {
IO.closeQuietly(fis);
IO.closeQuietly(ois);
}
return info;
}
private static String replaceNonAlphanumeric(final String string, final char character) {
final StringBuffer buffer = new StringBuffer(string.length());
for (final char singleChar : string.toCharArray()) {
if (Character.isLetterOrDigit(singleChar)) {
buffer.append(singleChar);
} else {
buffer.append(character);
}
}
return buffer.toString();
}
private String generateFilename(final URL url) {
return cachePath + File.separator + "feed_" + replaceNonAlphanumeric(url.toString(), '_').trim();
}
}