| /** |
| * 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; |
| |
| /** |
| * Built in scope implementations. |
| * |
| * @author crazybob@google.com (Bob Lee) |
| */ |
| public class Scopes { |
| |
| private Scopes() {} |
| |
| /** |
| * Name of the default scope. |
| */ |
| public static final String DEFAULT_NAME = "DEFAULT"; |
| |
| /** |
| * 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; |
| } |
| }; |
| |
| /** |
| * Name of container scope. |
| */ |
| public static final String CONTAINER_NAME = "CONTAINER"; |
| |
| /** |
| * 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 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(); |
| } |
| }; |
| } |
| }; |
| } |