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.sentry.core.common.service; import java.io.IOException; import java.util.HashSet; import java.util.List; import java.util.Set; import org.apache.commons.lang.StringUtils; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.security.Groups; import com.google.common.collect.Lists; import org.apache.sentry.core.common.exception.SentryGroupNotFoundException; public class HadoopGroupMappingService implements GroupMappingService { private static Configuration hadoopConf; private final Groups groups; public HadoopGroupMappingService(Groups groups) { this.groups = groups; } public HadoopGroupMappingService(Configuration conf, String resource) { if (hadoopConf == null) { synchronized (HadoopGroupMappingService.class) { if (hadoopConf == null) { // clone the current config and add resource path hadoopConf = new Configuration(); hadoopConf.addResource(conf); if (!StringUtils.isEmpty(resource)) { hadoopConf.addResource(resource); } } } } this.groups = Groups.getUserToGroupsMappingService(hadoopConf); } @Override public Set<String> getGroups(String user) { List<String> groupList = Lists.newArrayList(); try { groupList = groups.getGroups(user); } catch (IOException e) { throw new SentryGroupNotFoundException("Unable to obtain groups for " + user, e); } if (groupList == null || groupList.isEmpty()) { throw new SentryGroupNotFoundException("Unable to obtain groups for " + user); } return new HashSet<String>(groupList); } }