| /* |
| * 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.openide.util.lookup.implspi; |
| |
| import java.lang.ref.Reference; |
| import java.lang.ref.WeakReference; |
| import java.util.Collections; |
| import java.util.HashMap; |
| import java.util.Map; |
| import org.openide.util.Lookup; |
| import org.openide.util.lookup.Lookups; |
| |
| /** Infrastructure provider interface for those who control the overall |
| * registration of services in the system. The first instance of this interface |
| * found in {@link Lookup#getDefault()} is consulted when providing answers |
| * to {@link Lookups#forPath(java.lang.String)} queries. Current implementation |
| * is not ready for multiple instances of this interface (the first one wins) |
| * and also changing the instances during runtime. |
| * |
| * <div class="nonnormative"> |
| * The basic implementation of this interface is provided in |
| * <a href="@org-openide-filesystems@/overview-summary.html">Filesystem API</a> |
| * and recognizes the |
| * <a href="@org-openide-util@/org/openide/util/doc-files/api.html#instance-folders">.instance files</a> |
| * registered in XML layers. As such one can rely on |
| * <a href="@org-openide-util@/org/openide/util/doc-files/api.html#instance-folders">.instance files</a> |
| * being recognized in unit tests, if the |
| * <a href="@org-openide-filesystems@/overview-summary.html">Filesystem API</a> |
| * is included. |
| * The implementation |
| * is then refined in |
| * <a href="@org-netbeans-modules-settings@/overview-summary.html">Settings API</a> |
| * to handle also <a href="@org-openide-util@/org/openide/util/doc-files/api.html#settings">.settings files</a>. |
| * Again, including this module in unit tests |
| * ensures |
| * <a href="@org-openide-util@/org/openide/util/doc-files/api.html#settings">.settings files</a> |
| * files are recognized. |
| * </div> |
| * |
| * @author Jaroslav Tulach |
| * @since 8.1 |
| */ |
| public abstract class NamedServicesProvider { |
| private static final Map<String,Reference<Lookup>> namedServicesProviders = Collections.synchronizedMap(new HashMap<String,Reference<Lookup>>()); |
| private static ThreadLocal<Boolean> IN = new ThreadLocal<Boolean>(); |
| |
| public static Lookup forPath(String path) { |
| |
| Reference<Lookup> ref = namedServicesProviders.get(path); |
| Lookup lkp = ref == null ? null : ref.get(); |
| if (lkp != null) { |
| return lkp; |
| } |
| NamedServicesProvider prov = Lookup.getDefault().lookup(NamedServicesProvider.class); |
| if (prov != null && IN.get() == null) { |
| IN.set(true); |
| try { |
| lkp = prov.create(path); |
| } finally { |
| IN.set(null); |
| } |
| } else { |
| ClassLoader l = Lookup.getDefault().lookup(ClassLoader.class); |
| if (l == null) { |
| l = Thread.currentThread().getContextClassLoader(); |
| if (l == null) { |
| l = NamedServicesProvider.class.getClassLoader(); |
| } |
| } |
| lkp = Lookups.metaInfServices(l, "META-INF/namedservices/" + path); |
| } |
| |
| namedServicesProviders.put(path, new WeakReference<Lookup>(lkp)); |
| return lkp; |
| } |
| |
| /** Finds a config object under given path. |
| * @param filePath path to .instance or .settings file |
| * @param type the requested type for given object |
| * @return either null or instance of requested type |
| * @since 8.10 |
| */ |
| public static <T> T getConfigObject(String filePath, Class<T> type) { |
| NamedServicesProvider prov = Lookup.getDefault().lookup(NamedServicesProvider.class); |
| return prov != null ? prov.lookupObject(filePath, type) : null; |
| } |
| |
| /** Allows the providers to donate a special lookup for a given object. |
| * Right now it is used only for obtaining <code>FileObject.getLookup</code>. |
| * |
| * @param obj the object to find lookup for |
| * @return <code>null</code> or new lookup to be associated with the <code>obj</code> |
| * @since 8.17 |
| */ |
| public static Lookup createLookupFor(Object obj) { |
| NamedServicesProvider prov = Lookup.getDefault().lookup(NamedServicesProvider.class); |
| return prov != null ? prov.lookupFor(obj) : null; |
| } |
| |
| static void clearCache() { |
| boolean assertsOn = false; |
| assert assertsOn = true; |
| if (!assertsOn) { |
| throw new IllegalStateException(); |
| } |
| namedServicesProviders.clear(); |
| } |
| |
| /** Throws an exception. Prevents unwanted instantiation of this class |
| * by unknown subclasses. |
| */ |
| protected NamedServicesProvider() { |
| if (getClass().getName().equals("org.openide.util.lookup.PathInLookupTest$P")) { // NOI18N |
| // OK for tests |
| return; |
| } |
| if (getClass().getName().equals("org.openide.util.UtilitiesTest$NamedServicesProviderImpl")) { // NOI18N |
| // OK for tests |
| return; |
| } |
| if (getClass().getName().equals("org.netbeans.modules.openide.filesystems.RecognizeInstanceFiles")) { // NOI18N |
| // OK for openide.filesystems |
| return; |
| } |
| if (getClass().getName().equals("org.netbeans.modules.settings.RecognizeInstanceObjects")) { // NOI18N |
| // OK for settings |
| return; |
| } |
| throw new IllegalStateException(); |
| } |
| |
| /** Create the lookup for given path. Called as a result of query to |
| * {@link Lookups#forPath(java.lang.String)}. |
| * |
| * @param path the identification of the path |
| * @return the lookup representing objects in this path. |
| */ |
| protected abstract Lookup create(String path); |
| |
| /** Finds a config object under given path. Called from {@link FileUtil#getConfigObject}. |
| * @param filePath path to .instance or .settings file |
| * @param type the requested type for given object |
| * @return either null or instance of requested type |
| * @since 8.10 |
| */ |
| protected <T> T lookupObject(String path, Class<T> type) { |
| return create(path).lookup(type); |
| } |
| |
| /** Method for providers to work in orchestration with {@link #createLookupFor(java.lang.Object)}. |
| * By default return <code>null</code>. |
| * |
| * @param obj the object to find lookup for |
| * @return <code>null</code> or new lookup to be associated with the <code>obj</code> |
| * @since 8.17 |
| */ |
| protected Lookup lookupFor(Object obj) { |
| return null; |
| } |
| } |
