| /** |
| * 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.internal; |
| |
| import java.lang.reflect.Proxy; |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| /** |
| * Context of a dependency construction. Used to manage circular references. |
| * |
| * @author crazybob@google.com (Bob Lee) |
| */ |
| final class ConstructionContext<T> { |
| |
| T currentReference; |
| boolean constructing; |
| |
| List<DelegatingInvocationHandler<T>> invocationHandlers; |
| |
| public T getCurrentReference() { |
| return currentReference; |
| } |
| |
| public void removeCurrentReference() { |
| this.currentReference = null; |
| } |
| |
| public void setCurrentReference(T currentReference) { |
| this.currentReference = currentReference; |
| } |
| |
| public boolean isConstructing() { |
| return constructing; |
| } |
| |
| public void startConstruction() { |
| this.constructing = true; |
| } |
| |
| public void finishConstruction() { |
| this.constructing = false; |
| invocationHandlers = null; |
| } |
| |
| public Object createProxy(Errors errors, Class<?> expectedType) throws ErrorsException { |
| // TODO: if I create a proxy which implements all the interfaces of |
| // the implementation type, I'll be able to get away with one proxy |
| // instance (as opposed to one per caller). |
| |
| if (!expectedType.isInterface()) { |
| throw errors.cannotSatisfyCircularDependency(expectedType).toException(); |
| } |
| |
| if (invocationHandlers == null) { |
| invocationHandlers = new ArrayList<DelegatingInvocationHandler<T>>(); |
| } |
| |
| DelegatingInvocationHandler<T> invocationHandler = new DelegatingInvocationHandler<T>(); |
| invocationHandlers.add(invocationHandler); |
| |
| ClassLoader classLoader = BytecodeGen.getClassLoader(expectedType); |
| return expectedType.cast(Proxy.newProxyInstance(classLoader, |
| new Class[] { expectedType, CircularDependencyProxy.class }, invocationHandler)); |
| } |
| |
| public void setProxyDelegates(T delegate) { |
| if (invocationHandlers != null) { |
| for (DelegatingInvocationHandler<T> handler : invocationHandlers) { |
| handler.setDelegate(delegate); |
| } |
| } |
| } |
| } |