impl/owl/OWLCacheImpl.java

	OWLCacheImpl.java revision 2
//The MIT License
//
// Copyright (c) 2004 Evren Sirin
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.

/*
 * Created on Dec 30, 2003
 *
 */
package impl.owl;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.URI;
import java.util.Properties;

import org.mindswap.owl.OWLCache;
import org.xml.sax.InputSource;

/**
 *
 *
 *
 * @author Evren Sirin
 *
 */
public class OWLCacheImpl implements OWLCache {
    protected Properties cache = new Properties();
    protected String localCacheDirectory = null;
    protected boolean forced = true;

    /**
     * Forces the readers to use the cached copies of the files even if the remote
     * file may be available. When the forcing of cache is enabled the reader will
     * first check if the cached copy exists and then only try to use the remote file
     * when there is no cached copy.
     *
     * @param b
     */
    public void setForced(boolean b) {
        forced = b;
    }

    /**
     * Returns if the using of cache is forced.
     *
     * @return
     */
    public boolean isForced() {
        return forced;
    }

    /**
     * Sets the cache dir for the inference engine to find the cached files when a
     * file cannot be downparseed from its original URL. The cache dir should include
     * a file named service.idx. This index file is a text file where each line is in
     * the format
     * [service description url]=[local filename]
     *
     * The ':' characters in the url's should be escaped as "\:"
     *
     * @param dir sets the local cache directory. if null it forces not to use the cache.
     *            if the given dir or index file inthat dir does not exist then nothing is
     *            done
     */
    public void setLocalCacheDirectory( String dir ) {
        localCacheDirectory = dir;
        if(dir == null) {
            cache.clear();
            System.out.println("INFO: Local cache directory is disabled");
        }
        else {
            String indexFileName = localCacheDirectory + File.separator + "service.idx";
            try {
                File indexFile = new File( indexFileName );

                cache = new Properties();

                cache.load(new FileInputStream(indexFile));

                System.out.println("INFO: Cache has been initialized with " + cache.size() + " entries");
            } catch(FileNotFoundException e) {
                System.err.println("ERROR: Cache index file " + indexFileName + " cannot be found");
                localCacheDirectory = null;
            } catch(IOException e) {
                System.err.println("ERROR: Cache index file " + indexFileName + " has an invalid format");
                localCacheDirectory = null;
            }
        }
    }

    /*
     *  (non-Javadoc)
     * @see org.mindswap.owl.OWLCache#getLocalCacheDirectory()
     */
    public String getLocalCacheDirectory() {
        return localCacheDirectory;
    }


    /**
     * Returns the cached File object for the given URI. Returns null if there isn't an entry in the
     * cache for the given file or cached file is not found.
     *
     * @param fileURI
     * @return
     */
    public InputSource getCachedFile(String fileURI) {
        InputSource in = null;

        try {
            if(cache == null) return null;

            if(fileURI.endsWith("#")) fileURI = fileURI.substring(0, fileURI.length() - 1);

            String localFileName = cache.getProperty(fileURI);
            if(localFileName != null) {
                File file = new File(localFileName);
                if(!file.exists() && localCacheDirectory != null)
                    file = new File(localCacheDirectory + File.separator + localFileName);
                if(!file.exists()) {
                    System.out.println("WARNING: Cached file does not exist " + file);
                }
                else {
                    System.err.println("INFO: Using cached file " + file + " for URI " + fileURI);
                    in = new InputSource(new FileInputStream(file));
                }
            }
        }
        catch(Exception e) {
        }

        return in;
    }


    /**
     * Add a local file to be used as a cached copy for the given URI.
     *
     * @param fileURI URI for the remote file
     * @param localFile Path for the local cached copy
     */
    public void addCachedFile(String fileURI, File localFile) {
        cache.setProperty(fileURI, localFile.getName());
    }

    public void updateCachedFile(URI uri) {
    }


    /*
     *  (non-Javadoc)
     * @see org.mindswap.owl.OWLCache#updateIndexFile()
     */
    public void updateIndexFile() {
        String indexFileName = getLocalCacheDirectory() + File.separator + "service.idx";
        try {
            cache.store(new FileOutputStream(indexFileName), "");
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}