core/src/main/java/org/apache/commons/proxy/impl/AbstractProxyFactory.java

/*
 * 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.proxy.impl;

import org.apache.commons.proxy.Interceptor;
import org.apache.commons.proxy.Invoker;
import org.apache.commons.proxy.ObjectProvider;
import org.apache.commons.proxy.ProxyFactory;

/**
 * Base abstract {@link ProxyFactory} implementation, primarily providing
 * implementations of the interface methods that are typically convenience
 * constructs over the other methods.
 */
public abstract class AbstractProxyFactory implements ProxyFactory
{
    /**
     * Returns true if all <code>proxyClasses</code> are interfaces.
     *
     * @param proxyClasses the proxy classes
     * @return true if all <code>proxyClasses</code> are interfaces
     */
    public boolean canProxy( Class<?>... proxyClasses )
    {
        for( Class<?> proxyClass : proxyClasses )
        {
            if( !proxyClass.isInterface() )
            {
                return false;
            }
        }
        return true;
    }

    /**
     * Creates a proxy which delegates to the object provided by <code>delegateProvider</code>.  The proxy will be
     * generated using the current thread's "context class loader."
     *
     * @param delegateProvider the delegate provider
     * @param proxyClasses     the interfaces that the proxy should implement
     * @return a proxy which delegates to the object provided by the target object provider
     */
    public Object createDelegatorProxy( ObjectProvider<?> delegateProvider, Class<?>... proxyClasses )
    {
        return createDelegatorProxy(Thread.currentThread().getContextClassLoader(), delegateProvider, proxyClasses);
    }

    /**
     * Creates a proxy which delegates to the object provided by <code>delegateProvider</code>.  The proxy will be
     * generated using the current thread's "context class loader."
     *
     * @param delegateProvider the delegate provider
     * @param proxyClass     the class/interface that the proxy should implement
     * @return a proxy which delegates to the object provided by the target object provider
     */
    @SuppressWarnings("unchecked")
    public <T> T createDelegatorProxy( ObjectProvider<T> delegateProvider, Class<T> proxyClass )
    {
        return (T)createDelegatorProxy(delegateProvider, new Class[] {proxyClass});
    }

    /**
     * Creates a proxy which delegates to the object provided by <code>delegateProvider</code>.
     *
     * @param classLoader      the class loader to use when generating the proxy
     * @param delegateProvider the delegate provider
     * @param proxyClass     the class/interface that the proxy should implement
     * @return a proxy which delegates to the object provided by the target <code>delegateProvider>
     */
    @SuppressWarnings( "unchecked" )
    public <T> T createDelegatorProxy( ClassLoader classLoader, ObjectProvider<T> delegateProvider,
                                       Class<T> proxyClass )
    {
        return ( T ) createDelegatorProxy(classLoader, delegateProvider, new Class[] {proxyClass});
    }

    /**
     * Creates a proxy which passes through a {@link Interceptor interceptor} before eventually reaching the
     * <code>target</code> object.  The proxy will be generated using the current thread's "context class loader."
     *
     * @param target       the target object
     * @param interceptor  the method interceptor
     * @param proxyClasses the interfaces that the proxy should implement
     * @return a proxy which passes through a {@link Interceptor interceptor} before eventually reaching the
     *         <code>target</code> object.
     */
    public Object createInterceptorProxy( Object target, Interceptor interceptor,
                                          Class<?>... proxyClasses )
    {
        return createInterceptorProxy(Thread.currentThread().getContextClassLoader(), target, interceptor,
                                      proxyClasses);
    }

    /**
     * Creates a proxy which passes through a {@link Interceptor interceptor} before eventually reaching the
     * <code>target</code> object.  The proxy will be generated using the current thread's "context class loader."
     *
     * @param target       the target object
     * @param interceptor  the method interceptor
     * @param proxyClass the class/interface that the proxy should implement
     * @return a proxy which passes through a {@link Interceptor interceptor} before eventually reaching the
     *         <code>target</code> object.
     */
    @SuppressWarnings( "unchecked" )
    public <T> T createInterceptorProxy( Object target, Interceptor interceptor,
                                         Class<T> proxyClass )
    {
        return ( T ) createInterceptorProxy(target, interceptor, new Class[] {proxyClass});
    }

    /**
     * Creates a proxy which passes through a {@link Interceptor interceptor} before eventually reaching the
     * <code>target</code> object.
     *
     * @param classLoader  the class loader to use when generating the proxy
     * @param target       the target object
     * @param interceptor  the method interceptor
     * @param proxyClass the class/interface that the proxy should implement.
     * @return a proxy which passes through a {@link Interceptor interceptor} before eventually reaching the
     *         <code>target</code> object.
     */
    @SuppressWarnings( "unchecked" )
    public <T> T createInterceptorProxy( ClassLoader classLoader,
                                         Object target,
                                         Interceptor interceptor,
                                         Class<T> proxyClass )
    {
        return ( T ) createInterceptorProxy(classLoader, target, interceptor, new Class[] {proxyClass});
    }

    /**
     * Creates a proxy which uses the provided {@link Invoker} to handle all method invocations.  The proxy will be
     * generated using the current thread's "context class loader."
     *
     * @param invoker      the invoker
     * @param proxyClasses the interfaces that the proxy should implement
     * @return a proxy which uses the provided {@link Invoker} to handle all method invocations
     */
    public Object createInvokerProxy( Invoker invoker, Class<?>... proxyClasses )
    {
        return createInvokerProxy(Thread.currentThread().getContextClassLoader(), invoker,
                                  proxyClasses);
    }

    /**
     * Creates a proxy which uses the provided {@link Invoker} to handle all method invocations.  The proxy will be
     * generated using the current thread's "context class loader."
     *
     * @param invoker      the invoker
     * @param proxyClass the class/interface that the proxy should implement
     * @return a proxy which uses the provided {@link Invoker} to handle all method invocations
     */
    @SuppressWarnings( "unchecked" )
    public <T> T createInvokerProxy( Invoker invoker, Class<T> proxyClass )
    {
        return ( T ) createInvokerProxy(invoker, new Class[] {proxyClass});
    }

    /**
     * Creates a proxy which uses the provided {@link Invoker} to handle all method invocations.
     *
     * @param classLoader  the class loader to use when generating the proxy
     * @param invoker      the invoker
     * @param proxyClass the class/interface that the proxy should implement
     * @return a proxy which uses the provided {@link Invoker} to handle all method invocations
     */
    @SuppressWarnings( "unchecked" )
    public <T> T createInvokerProxy( ClassLoader classLoader, Invoker invoker,
                                     Class<T> proxyClass )
    {
        return ( T ) createInvokerProxy(classLoader, invoker, new Class[] {proxyClass});
    }

}