| /* |
| * 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.commons.proxy2.impl; |
| |
| import java.io.Serializable; |
| import java.lang.reflect.Constructor; |
| import java.lang.reflect.Modifier; |
| import java.util.LinkedHashSet; |
| import java.util.Set; |
| |
| import org.apache.commons.proxy2.exception.ProxyFactoryException; |
| |
| /** |
| * Parent {@link AbstractProxyFactory} for implementations that permit the generation of proxies with a specific |
| * inheritance hierarchy. |
| */ |
| public abstract class AbstractSubclassingProxyFactory extends AbstractProxyFactory |
| { |
| //****************************************************************************************************************** |
| // ProxyFactory Implementation |
| //****************************************************************************************************************** |
| |
| /** |
| * Returns true if a suitable superclass can be found, given the desired <code>proxyClasses</code>. |
| * |
| * @param proxyClasses |
| * the proxy classes |
| * @return true if a suitable superclass can be found, given the desired <code>proxyClasses</code> |
| */ |
| @Override |
| public boolean canProxy(Class<?>... proxyClasses) |
| { |
| try |
| { |
| getSuperclass(proxyClasses); |
| return true; |
| } |
| catch (ProxyFactoryException e) |
| { |
| return false; |
| } |
| } |
| |
| //****************************************************************************************************************** |
| // Other Methods |
| //****************************************************************************************************************** |
| |
| private static boolean hasSuitableDefaultConstructor(Class<?> superclass) |
| { |
| final Constructor<?>[] declaredConstructors = superclass.getDeclaredConstructors(); |
| for (int i = 0; i < declaredConstructors.length; i++) |
| { |
| Constructor<?> constructor = declaredConstructors[i]; |
| if (constructor.getParameterTypes().length == 0 |
| && (Modifier.isPublic(constructor.getModifiers()) || Modifier.isProtected(constructor |
| .getModifiers()))) |
| { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| private static Class<?>[] toNonInterfaces(Class<?>[] proxyClasses) |
| { |
| final Set<Class<?>> superclasses = new LinkedHashSet<Class<?>>(); |
| for (Class<?> proxyClass : proxyClasses) |
| { |
| if (!proxyClass.isInterface()) |
| { |
| superclasses.add(proxyClass); |
| } |
| } |
| return superclasses.toArray(new Class[superclasses.size()]); |
| } |
| |
| /** |
| * Returns the <code>proxyClasses</code> transformed into an array of only the interface classes. |
| * <p/> |
| * <b>Note</b>: This class will append {@link Serializable} to the end of the list if it's not found! |
| * |
| * @param proxyClasses |
| * the proxy classes |
| * @return the <code>proxyClasses</code> transformed into an array of only the interface classes |
| */ |
| protected static Class<?>[] toInterfaces(Class<?>[] proxyClasses) |
| { |
| final Set<Class<?>> interfaces = new LinkedHashSet<Class<?>>(); |
| for (Class<?> proxyClass : proxyClasses) |
| { |
| if (proxyClass.isInterface()) |
| { |
| interfaces.add(proxyClass); |
| } |
| } |
| interfaces.add(Serializable.class); |
| return interfaces.toArray(new Class[interfaces.size()]); |
| } |
| |
| /** |
| * Returns either {@link Object} if all of the <code>proxyClasses</code> are interfaces or the single non-interface |
| * class from <code>proxyClasses</code>. |
| * |
| * @param proxyClasses |
| * the proxy classes |
| * @return either {@link Object} if all of the <code>proxyClasses</code> are interfaces or the single non-interface |
| * class from <code>proxyClasses</code> |
| * @throws ProxyFactoryException |
| * if multiple non-interface classes are contained in <code>proxyClasses</code> or any of the |
| * non-interface classes are final |
| */ |
| public static Class<?> getSuperclass(Class<?>[] proxyClasses) |
| { |
| final Class<?>[] superclasses = toNonInterfaces(proxyClasses); |
| switch (superclasses.length) |
| { |
| case 0: |
| return Object.class; |
| case 1: |
| final Class<?> superclass = superclasses[0]; |
| if (Modifier.isFinal(superclass.getModifiers())) |
| { |
| throw new ProxyFactoryException("Proxy class cannot extend " + superclass.getName() |
| + " as it is final."); |
| } |
| if (!hasSuitableDefaultConstructor(superclass)) |
| { |
| throw new ProxyFactoryException("Proxy class cannot extend " + superclass.getName() |
| + ", because it has no visible \"default\" constructor."); |
| } |
| return superclass; |
| default: |
| final StringBuilder errorMessage = new StringBuilder("Proxy class cannot extend "); |
| for (int i = 0; i < superclasses.length; i++) |
| { |
| Class<?> c = superclasses[i]; |
| errorMessage.append(c.getName()); |
| if (i != superclasses.length - 1) |
| { |
| errorMessage.append(", "); |
| } |
| } |
| errorMessage.append("; multiple inheritance not allowed."); |
| throw new ProxyFactoryException(errorMessage.toString()); |
| } |
| } |
| } |