Java tutorial
/* * Copyright 2019 ThoughtWorks, Inc. * * Licensed 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 com.thoughtworks.go.config.registry; import java.net.URL; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.ConcurrentMap; import com.thoughtworks.go.plugins.PluginExtensions; import com.thoughtworks.go.plugins.presentation.PluggableViewModel; import com.thoughtworks.go.plugins.presentation.PluggableViewModelFactory; import org.jdom2.Element; import org.jdom2.Namespace; import org.osgi.framework.BundleContext; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; /** * @understands mapping the implementers of a given Config interface. */ @Component public class ConfigElementImplementationRegistry implements ConfigElementRegistry { private final ConcurrentMap<Class, List<Class>> registry; private final ConcurrentMap<String, PluginNamespace> xsdsFor; private final ConcurrentMap<Class, PluggableViewModelFactory> viewRegistry; @Autowired public ConfigElementImplementationRegistry(PluginExtensions pluginExtns) { this.registry = new ConcurrentHashMap<>(); this.viewRegistry = new ConcurrentHashMap<>(); this.xsdsFor = new ConcurrentHashMap<>(); registerPluginExtensions(pluginExtns); } public <T> List<Class<? extends T>> implementersOf(Class<T> type) { List<Class<? extends T>> toReturn = new ArrayList<>(); //noinspection unchecked for (Class<? extends T> impl : registry.get(type)) { toReturn.add(impl); } return toReturn; } public String xsds() { StringBuilder builder = new StringBuilder(); for (PluginNamespace namespace : xsdsFor.values()) { builder.append(namespace.uri).append(" ").append(namespace.xsdResource).append(" "); } return builder.toString().trim(); } public void xsdFor(BundleContext bundleContext, URL url) { registerPluginNamespace(new PluginNamespace(bundleContext, url)); } public void registerNamespacesInto(Element element) { for (PluginNamespace namespace : xsdsFor.values()) { element.addNamespaceDeclaration(Namespace.getNamespace(namespace.prefix, namespace.uri)); } } @SuppressWarnings({ "unchecked" }) public <T> PluggableViewModel getViewModelFor(T model, String actionName) { return viewRegistry.get(model.getClass()).viewModelFor(model, actionName); } private void registerPluginNamespace(PluginNamespace pluginNamespace) { this.xsdsFor.putIfAbsent(pluginNamespace.uri, pluginNamespace); } private void registerPluginExtensions(PluginExtensions pluginExtns) { for (ConfigurationExtension configExtension : pluginExtns.configTagImplementations()) { for (ConfigTypeExtension typeExtension : configExtension.implementations) { Class impl = typeExtension.getImplementation(); //noinspection unchecked registerImplementer(typeExtension.getType(), impl); registerView(impl, typeExtension.getFactory()); } registerPluginNamespace(configExtension.pluginNamespace); } } public <T> void registerImplementer(Class<T> configInterface, Class<? extends T>... implementation) { List<Class> set; if (registry.containsKey(configInterface)) { set = registry.get(configInterface); } else {//TODO: concurrency issue -jj (someone sets set before putIfAbsent) List<Class> newSet = Collections.synchronizedList(new ArrayList<>()); set = registry.putIfAbsent(configInterface, newSet); if (set == null) { set = newSet; } } set.addAll(Arrays.asList(implementation)); } public void registerView(final Class klazz, final PluggableViewModelFactory factory) { viewRegistry.putIfAbsent(klazz, factory); } }