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package org.linaro.connect;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.LinkedHashMap;
import java.util.Map;
/**
* A least recently used cache
*/
class LRUCache extends LinkedHashMap<String, File> {
private final static long serialVersionUID = 1L;
private final static int MAX_ENTRIES = 30;
private final File mCacheDir;
public LRUCache(File cacheDir) {
super(MAX_ENTRIES+1, 1, true);
mCacheDir = cacheDir;
for( File f: mCacheDir.listFiles() ) {
String url = toUrl(f);
put(url, f);
}
}
@Override
protected boolean removeEldestEntry(Map.Entry<String, File> eldest) {
return size() > MAX_ENTRIES;
}
public InputStream getInputStream(String url) throws IOException {
File f = get(url);
if( f != null ) {
try {
return new FileInputStream(f);
}
catch(IOException e) {
remove(url);
f.delete();
throw e;
}
}
File cacheFile = toCacheFile(url);
return new CachingInputStream(url, cacheFile);
}
private File toCacheFile(String url) {
//we change /'s to -'s. So we don't loose our -'s we escape them
String name = url.replace("-", "<DASH>");
name = name.replace('/', '-');
return new File(mCacheDir, name);
}
private String toUrl(File f) {
String name = f.getName();
name = name.replace('-', '/');
name = name.replace("<DASH>", "-");
return name;
}
private class CachingInputStream extends InputStream {
String mUrl;
File mCacheFile;
InputStream mIn;
OutputStream mOut;
public CachingInputStream(String url, File cache)
throws IOException {
mUrl = url;
mCacheFile = cache;
reset();
}
@Override
public int read() throws IOException {
throw new IOException("Not Implemented");
}
@Override
public int read(byte[] b) throws IOException {
return read(b, 0, b.length);
}
@Override
public int read(byte[] b, int offset, int length) throws IOException {
int bIn = mIn.read(b, offset, length);
if(bIn != -1)
mOut.write(b, offset, bIn);
return bIn;
}
@Override
public synchronized void reset() throws IOException {
if( mIn != null )
mIn.close();
if( mOut != null )
mOut.close();
URLConnection c = new URL(mUrl).openConnection();
mIn = c.getInputStream();
mOut = new FileOutputStream(mCacheFile);
}
@Override
public void close() throws IOException {
mIn.close();
mOut.close();
put(mUrl, mCacheFile);
}
}
}
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