| /* |
| * Copyright 2007 Rickard Öberg. |
| * |
| * 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 org.qi4j.library.invocationcache; |
| |
| import java.lang.reflect.InvocationHandler; |
| import java.lang.reflect.Method; |
| import java.util.Arrays; |
| import org.qi4j.api.common.AppliesTo; |
| import org.qi4j.api.concern.ConcernOf; |
| import org.qi4j.api.injection.scope.This; |
| |
| /** |
| * Return value of @Cached calls on exceptions. |
| * <p> |
| * If an Exception occurs, try to reuse a previous result. Don't do anything on Throwables. |
| * </p> |
| */ |
| @AppliesTo( Cached.class ) |
| public class ReturnCachedValueOnExceptionConcern |
| extends ConcernOf<InvocationHandler> |
| implements InvocationHandler |
| { |
| @This |
| private InvocationCache cache; |
| |
| @Override |
| public Object invoke( Object proxy, Method method, Object[] args ) |
| throws Throwable |
| { |
| boolean voidReturnType = method.getReturnType().equals( Void.TYPE ); |
| if( cache != null || voidReturnType ) // Skip if void return type or no InvocationCache has been defined. |
| { |
| String cacheName = method.getName(); |
| if( args != null ) |
| { |
| cacheName += Arrays.asList( args ); |
| } |
| try |
| { |
| // Invoke method |
| Object result = next.invoke( proxy, method, args ); |
| // update cache |
| cache.setCachedValue( cacheName, result ); |
| return result; |
| } |
| catch( Exception e ) |
| { |
| // Try cache |
| return cache.cachedValue( cacheName ); |
| } |
| } |
| // if no InvocationCache is present. |
| return next.invoke( proxy, method, args ); |
| } |
| } |