Java tutorial
/** * 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.camel.component.hdfs2; import java.net.URI; import java.util.Map; import java.util.ServiceLoader; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FileSystem; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * <p>Class which may be used in OSGi/Blueprint environment to perform some static initialization</p> * <p>This could be useful to fix the usage of {@link ServiceLoader} by Hadoop 2 in OSGi environment.</p> */ public class HdfsOsgiHelper { private static final Logger LOG = LoggerFactory.getLogger(HdfsOsgiHelper.class); /** * By using this constructor it is possible to perform static initialization of {@link FileSystem}. */ public HdfsOsgiHelper(Map<String, String> fileSystems) { try { // get bundle classloader for camel-hdfs2 bundle ClassLoader cl = getClass().getClassLoader(); Configuration conf = new Configuration(); for (String key : fileSystems.keySet()) { URI uri = URI.create(key); conf.setClass(String.format("fs.%s.impl", uri.getScheme()), cl.loadClass(fileSystems.get(key)), FileSystem.class); FileSystem.get(uri, conf); } } catch (Exception e) { LOG.debug(e.getMessage()); } } }