/* | |
* 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.apache.felix.ipojo.handlers.providedservice.strategy; | |
import java.lang.reflect.InvocationHandler; | |
import java.lang.reflect.Method; | |
import org.apache.felix.ipojo.ComponentInstance; | |
import org.apache.felix.ipojo.IPOJOServiceFactory; | |
/** | |
* This proxy class is here to wrap an iPOJO ServiceFactory. | |
* If the consumer of this service do not call the getService or ungetService | |
* methods, it will get an Exception with an explicit error message telling | |
* him that this service is only usable through iPOJO. | |
* @author <a href="mailto:dev@felix.apache.org">Felix Project Team</a> | |
*/ | |
public class ErrorPrintingServiceFactoryProxy implements InvocationHandler { | |
/** | |
* getService(ComponentInstance) method. | |
*/ | |
private static Method GET_METHOD; | |
/** | |
* ungetService(ComponentInstance, Object) method. | |
*/ | |
private static Method UNGET_METHOD; | |
/** | |
* Wrapped factory. | |
*/ | |
private final IPOJOServiceFactory m_factory; | |
static { | |
// Static initialization of theses constants. | |
try { | |
GET_METHOD = IPOJOServiceFactory.class.getMethod("getService", | |
new Class[]{ComponentInstance.class}); | |
UNGET_METHOD = IPOJOServiceFactory.class.getMethod("ungetService", | |
new Class[]{ComponentInstance.class, Object.class}); | |
} catch (Exception e) { | |
// Should never happen | |
} | |
} | |
/** | |
* Wraps a ServiceFactory in an InvocationHandler that will delegate only | |
* get/ungetService methods to the factory. All other methods will be | |
* rejected with a meaningful error message. | |
* | |
* @param factory delegating iPOJO ServiceFactory | |
*/ | |
public ErrorPrintingServiceFactoryProxy(final IPOJOServiceFactory factory) { | |
this.m_factory = factory; | |
} | |
/** | |
* 'Invoke' methods called when a method is called on the proxy. | |
* @param proxy the proxy | |
* @param method the method | |
* @param args the arguments | |
* @return the result | |
* @throws Exception if something wrong happens | |
* @see java.lang.reflect.InvocationHandler#invoke(java.lang.Object, java.lang.reflect.Method, java.lang.Object[]) | |
*/ | |
public Object invoke(final Object proxy, | |
final Method method, | |
final Object[] args) throws Exception { | |
// Handle get/unget operations | |
if (GET_METHOD.equals(method)) { | |
return m_factory.getService((ComponentInstance) args[0]); | |
} | |
if (UNGET_METHOD.equals(method)) { | |
m_factory.ungetService((ComponentInstance) args[0], args[1]); | |
return null; | |
} | |
// All other methods are rejected | |
throw new UnsupportedOperationException("This service requires an advanced creation policy. " | |
+ "Before calling the service, call the IPOJOServiceFactory.getService(ComponentInstance) " | |
+ "method to get the service object. "); | |
} | |
} |