/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.marmotta.commons.http;
import org.apache.marmotta.commons.sesame.repository.ResourceUtils;
import org.openrdf.model.BNode;
import org.openrdf.model.Resource;
import org.openrdf.model.Statement;
import org.openrdf.model.URI;
import org.openrdf.repository.RepositoryConnection;
import org.openrdf.repository.RepositoryException;
import org.openrdf.repository.RepositoryResult;
import com.google.common.hash.HashFunction;
import com.google.common.hash.Hasher;
import com.google.common.hash.Hashing;
/**
* HTTP ETag generator for Sesame
*
* @author Sergio Fernández
*
*/
public class ETagGenerator {
public static String getETag(RepositoryConnection conn, String uri) throws RepositoryException {
URI resource = ResourceUtils.getUriResource(conn, uri);
return getETag(conn, resource);
}
public static String getETag(RepositoryConnection conn, URI resource) throws RepositoryException {
if (resource == null) return "";
Hasher hasher = buildHasher();
hasher.putString(resource.stringValue());
//FIXME: The order of the statements is not defined -> might result in different hash!
RepositoryResult<Statement> outgoing = conn.getStatements(resource, null, null, true);
try {
while (outgoing.hasNext()) {
Statement statement = outgoing.next();
hasher.putString(statement.getPredicate().stringValue());
hasher.putString(statement.getObject().stringValue());
//TODO: statement modification date?
}
} finally {
outgoing.close();
}
RepositoryResult<Statement> incoming = conn.getStatements(null, null, resource, true);
try {
while (incoming.hasNext()) {
Statement statement = incoming.next();
hasher.putString(statement.getSubject().stringValue());
hasher.putString(statement.getPredicate().stringValue());
//TODO: statement modification date?
}
} finally {
incoming.close();
}
return hasher.hash().toString();
}
public static String getWeakETag(RepositoryConnection conn, String resource) throws RepositoryException {
if (resource.startsWith("http://")) {
return getWeakETag(conn, ResourceUtils.getUriResource(conn, resource));
} else {
return getWeakETag(conn, ResourceUtils.getAnonResource(conn, resource));
}
}
// public static String getWeakETag(RepositoryConnection conn, Resource resource) throws RepositoryException {
// if (resource instanceof URI) {
// return getWeakETag(conn, (URI)resource);
// } else if (resource instanceof BNode) {
// return getWeakETag(conn, (BNode)resource);
// } else {
// return null;
// }
// }
public static String getWeakETag(RepositoryConnection conn, Resource resource) throws RepositoryException {
if (resource == null) return "";
Hasher hasher = buildHasher();
hasher.putString(resource.stringValue());
//FIXME: The order of the statements is not defined -> might result in different hash!
RepositoryResult<Statement> statements = conn.getStatements(resource, null, null, true);
try {
while (statements.hasNext()) {
Statement statement = statements.next();
hasher.putString(statement.getPredicate().stringValue());
hasher.putString(statement.getObject().stringValue());
//TODO: statement modification date?
}
} finally {
statements.close();
}
return hasher.hash().toString();
}
private static Hasher buildHasher() {
HashFunction function = Hashing.goodFastHash(16);
Hasher hasher = function.newHasher();
return hasher;
}
}