| /* |
| * 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.nutch.crawl; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| // Hadoop imports |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.nutch.util.ObjectCache; |
| |
| import java.lang.invoke.MethodHandles; |
| |
| /** |
| * Factory class, which instantiates a Signature implementation according to the |
| * current Configuration configuration. This newly created instance is cached in |
| * the Configuration instance, so that it could be later retrieved. |
| * |
| * @author Andrzej Bialecki <ab@getopt.org> |
| */ |
| public class SignatureFactory { |
| private static final Logger LOG = LoggerFactory |
| .getLogger(MethodHandles.lookup().lookupClass()); |
| |
| private SignatureFactory() { |
| } // no public ctor |
| |
| /** Return the default Signature implementation. */ |
| public synchronized static Signature getSignature(Configuration conf) { |
| String clazz = conf.get("db.signature.class", MD5Signature.class.getName()); |
| ObjectCache objectCache = ObjectCache.get(conf); |
| Signature impl = (Signature) objectCache.getObject(clazz); |
| if (impl == null) { |
| try { |
| if (LOG.isInfoEnabled()) { |
| LOG.info("Using Signature impl: " + clazz); |
| } |
| Class<?> implClass = Class.forName(clazz); |
| impl = (Signature) implClass.getConstructor().newInstance(); |
| impl.setConf(conf); |
| objectCache.setObject(clazz, impl); |
| } catch (Exception e) { |
| throw new RuntimeException("Couldn't create " + clazz, e); |
| } |
| } |
| return impl; |
| } |
| } |