/**
Copyright (C) SYSTAP, LLC 2006-2012. 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 com.bigdata.rdf.graph.util;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URISyntaxException;
import java.util.zip.GZIPInputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import org.apache.log4j.Logger;
import org.openrdf.model.Resource;
import org.openrdf.model.Statement;
import org.openrdf.model.ValueFactory;
import org.openrdf.rio.RDFFormat;
import org.openrdf.rio.RDFHandlerException;
import org.openrdf.rio.RDFParseException;
import org.openrdf.rio.RDFParser;
import org.openrdf.rio.RDFParserFactory;
import org.openrdf.rio.RDFParserRegistry;
import org.openrdf.rio.helpers.RDFHandlerBase;
/**
* Utility to load data into a graph.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
*/
abstract public class GraphLoader {
private static final Logger log = Logger.getLogger(GASUtil.class);
/**
* Return the best guess at the {@link RDFFormat} for a resource.
* <p>
* Note: This handles the .gz and .zip extensions.
*
* @param n
* The name of the resource.
* @param rdfFormat
* The fallback format (optional).
*
* @return The best guess format.
*/
private RDFFormat guessRDFFormat(final String n, final RDFFormat rdfFormat) {
RDFFormat fmt = RDFFormat.forFileName(n);
if (fmt == null && n.endsWith(".zip")) {
fmt = RDFFormat.forFileName(n.substring(0, n.length() - 4));
}
if (fmt == null && n.endsWith(".gz")) {
fmt = RDFFormat.forFileName(n.substring(0, n.length() - 3));
}
if (fmt == null) // fallback
fmt = rdfFormat;
return fmt;
}
public void loadGraph(final RDFFormat fallback,
final String... resources) throws Exception {
if (resources != null) {
for (String resource : resources) {
loadGraph(fallback, resource);
}
}
}
/**
* Return the {@link ValueFactory} that will be set on the {@link RDFParser}
* . This is necessary for the RDR parser.
*/
abstract protected ValueFactory getValueFactory();
/**
* Load a resource from the classpath, the file system, or a URI. GZ
* compressed files are decompressed. Directories are processed recursively.
* The entries in a ZIP archive are processed. Resources that are not
* recognized as some {@link RDFFormat} will be ignored unless the
* <i>fallback</i> argument is given, in which case that format will be
* <em>assumed</em> for such resources.
*
* @param resource
* A resource on the class path, a file or a directory, or a URI.
* @param fallback
* The default {@link RDFFormat} to be assumed (optional).
*
* @throws IOException
* @throws URISyntaxException
* @throws RDFHandlerException
* @throws RDFParseException
*/
public void loadGraph(final RDFFormat fallback,
final String resource) throws IOException, URISyntaxException,
RDFParseException, RDFHandlerException {
if (log.isInfoEnabled())
log.info("Loading: " + resource);
String baseURI = null;
InputStream is = null;
try {
// try the classpath
is = getClass().getResourceAsStream(resource);
if (is != null) {
// set for resource on classpath.
baseURI = getClass().getResource(resource).toURI().toString();
} else {
// try file system.
final File file = new File(resource);
if (file.exists()) {
if (file.isDirectory()) {
/*
* Recursion.
*/
final File[] a = file.listFiles();
for (File f : a) {
if (file.isHidden()) {
if (log.isDebugEnabled())
log.debug("Skipping hidden file: " + file);
continue;
}
// recursion.
loadGraph(fallback, f.toString());
}
// end of directory.
return;
}
is = new FileInputStream(file);
// set for file as URI.
baseURI = file.toURI().toString();
} else {
throw new FileNotFoundException(
"Could not locate resource: " + resource);
}
}
if (resource.endsWith(".gz")) {
is = new GZIPInputStream(is);
} else if (resource.endsWith(".zip")) {
final ZipInputStream zis = new ZipInputStream(is);
try {
ZipEntry e;
while ((e = zis.getNextEntry()) != null) {
if (e.isDirectory()) {
// skip directories.
continue;
}
baseURI = resource + "/" + e.getName();
loadFromStream(zis, resource, baseURI, fallback);
final RDFFormat format = guessRDFFormat(e.getName(),
fallback);
if (format == null) {
if (log.isInfoEnabled())
log.info("Skipping non-RDF entry: resource="
+ resource + ", entry=" + e.getName());
continue;
}
}
return;
} finally {
zis.close();
}
}
loadFromStream(is, resource, baseURI, fallback);
} finally {
if (is != null) {
try {
is.close();
} catch (Throwable t) {
log.error(t);
}
}
}
}
private void loadFromStream(final InputStream is,
final String resource, final String baseURI,
final RDFFormat fallback) throws RDFParseException,
RDFHandlerException, IOException {
// guess at the RDF Format
final RDFFormat rdfFormat = guessRDFFormat(resource, fallback);
if (rdfFormat == null) {
if (log.isInfoEnabled())
log.info("Skipping non-RDF resource: " + resource);
return;
}
/*
* Obtain a buffered reader on the input stream.
*/
final Reader reader = new BufferedReader(new InputStreamReader(
is));
try {
final RDFParserFactory rdfParserFactory = RDFParserRegistry
.getInstance().get(rdfFormat);
final RDFParser rdfParser = rdfParserFactory.getParser();
rdfParser.setStopAtFirstError(false);
final ValueFactory vf = getValueFactory();
if (vf != null) {
rdfParser.setValueFactory(vf);
}
final AddStatementHandler h = newStatementHandler();
rdfParser.setRDFHandler(h);
/*
* Run the parser, which will cause statements to be
* inserted.
*/
rdfParser.parse(reader, baseURI);
if (log.isInfoEnabled())
log.info("Done: " + resource + ", nread=" + h.ntriples);
} finally {
try {
reader.close();
} catch (Throwable t) {
log.error(t);
}
}
}
/**
* Factory for the helper class that adds statements to the target
* graph.
*/
protected abstract AddStatementHandler newStatementHandler();
/**
* Helper class adds statements to the sail as they are visited by a parser.
*/
protected abstract class AddStatementHandler extends RDFHandlerBase {
/**
* Only used if the statements themselves do not have a context.
*/
private final Resource[] defaultContext;
protected long ntriples = 0;
/**
*
* @param conn
*/
public AddStatementHandler() {
this.defaultContext = new Resource[0];
}
@Override
public void handleStatement(final Statement stmt)
throws RDFHandlerException {
final Resource[] c = (Resource[])
(stmt.getContext() == null
? defaultContext
: new Resource[] { stmt.getContext() });
addStatement(stmt, c);
}
abstract protected void addStatement(final Statement stmt,
final Resource[] c) throws RDFHandlerException;
}
}