| /** |
| * 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.apex.engine.plugin.loaders; |
| |
| import java.util.ArrayList; |
| import java.util.Collection; |
| import java.util.List; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import org.apache.apex.engine.api.plugin.PluginLocator; |
| import org.apache.hadoop.conf.Configuration; |
| |
| import com.datatorrent.stram.StramUtils; |
| |
| public class PropertyBasedPluginLocator<T> implements PluginLocator<T> |
| { |
| private static final Logger LOG = LoggerFactory.getLogger(PropertyBasedPluginLocator.class); |
| private final Class<T> klass; |
| private final String propertyName; |
| |
| public PropertyBasedPluginLocator(Class<T> klass, String propertyName) |
| { |
| this.klass = klass; |
| this.propertyName = propertyName; |
| } |
| |
| @Override |
| public Collection<T> discoverPlugins(Configuration conf) |
| { |
| List<T> detectedPlugins = new ArrayList<>(); |
| String classNamesStr = conf.get(this.propertyName); |
| if (classNamesStr == null) { |
| return detectedPlugins; |
| } |
| |
| String[] classNames = classNamesStr.split(","); |
| for (String className : classNames) { |
| try { |
| Class<? extends T> plugin = StramUtils.classForName(className, this.klass); |
| detectedPlugins.add(StramUtils.newInstance(plugin)); |
| } catch (IllegalArgumentException e) { |
| LOG.warn("Could not load plugin {}", className); |
| } |
| } |
| return detectedPlugins; |
| } |
| } |