| /** |
| * Copyright (C) 2006 Google 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.google.inject; |
| |
| import com.google.inject.util.SurrogateAnnotations; |
| import com.google.inject.util.DuplicateAnnotationException; |
| |
| import java.util.Map; |
| import java.lang.annotation.Annotation; |
| |
| /** |
| * Built in scope implementations. |
| * |
| * @author crazybob@google.com (Bob Lee) |
| */ |
| public class Scopes { |
| |
| private Scopes() {} |
| |
| /** |
| * The default scope, one instance per injection. |
| */ |
| public static final Scope DEFAULT = new Scope() { |
| public <T> Factory<T> scope(Key<T> key, Factory<T> creator) { |
| return creator; |
| } |
| |
| public String toString() { |
| return "Scopes.DEFAULT"; |
| } |
| }; |
| |
| /** |
| * One instance per container. |
| */ |
| public static final Scope CONTAINER = new Scope() { |
| public <T> Factory<T> scope(Key<T> key, final Factory<T> creator) { |
| return new Factory<T>() { |
| |
| private volatile T instance; |
| |
| // DCL on a volatile is safe as of Java 5, which we obviously require. |
| @SuppressWarnings("DoubleCheckedLocking") |
| public T get() { |
| if (instance == null) { |
| /* |
| * Use a pretty coarse lock. We don't want to run into deadlocks |
| * when two threads try to load circularly-dependent objects. |
| * Maybe one of these days we will identify independent graphs of |
| * objects and offer to load them in parallel. |
| */ |
| synchronized (Container.class) { |
| if (instance == null) { |
| instance = creator.get(); |
| } |
| } |
| } |
| return instance; |
| } |
| |
| public String toString() { |
| return creator.toString(); |
| } |
| }; |
| } |
| |
| public String toString() { |
| return "Scopes.CONTAINER"; |
| } |
| }; |
| |
| /** |
| * Gets the scope for a type based on its annotations. Returns {@code null} |
| * if none specified. |
| * |
| * @param implementation type |
| * @param scopes map of scope names to scopes |
| * @param errorHandler handles errors |
| */ |
| static Scope getScopeForType(Class<?> implementation, |
| Map<Class<? extends Annotation>, Scope> scopes, |
| ErrorHandler errorHandler) { |
| Scope found = null; |
| for (Annotation annotation : implementation.getAnnotations()) { |
| Scope scope = scopes.get(annotation.annotationType()); |
| if (scope != null) { |
| if (found != null) { |
| errorHandler.handle(ErrorMessages.DUPLICATE_SCOPE_ANNOTATIONS, |
| implementation, found, scope); |
| } else { |
| found = scope; |
| } |
| } |
| } |
| return found; |
| } |
| |
| /** |
| * Scopes an internal factory. |
| */ |
| static <T> InternalFactory<? extends T> scope(Key<T> key, |
| ContainerImpl container, InternalFactory<? extends T> creator, |
| Scope scope) { |
| // Default scope does nothing. |
| if (scope == null || scope == DEFAULT) { |
| return creator; |
| } |
| Factory<T> scoped = scope.scope(key, |
| new FactoryToInternalFactoryAdapter<T>(container, creator)); |
| return new InternalFactoryToFactoryAdapter<T>(scoped); |
| } |
| } |