Proxies.java

package org.rapidoid.cls;

import org.rapidoid.RapidoidThing;
import org.rapidoid.log.Log;
import org.rapidoid.u.U;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Arrays;

/*
 * #%L
 * rapidoid-commons
 * %%
 * Copyright (C) 2014 - 2017 Nikolche Mihajlovski and contributors
 * %%
 * 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.
 * #L%
 */

public class Proxies extends RapidoidThing {

	@SuppressWarnings("unchecked")
	public static <T> T createProxy(InvocationHandler handler, Class<?>... interfaces) {
		return ((T) Proxy.newProxyInstance(interfaces[0].getClassLoader(), interfaces, handler));
	}

	public static <T> T implement(final Object target, final InvocationHandler handler, Class<?>... interfaces) {
		final Class<?> targetClass = target.getClass();

		return createProxy(new InvocationHandler() {

			@Override
			public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

				if (method.getDeclaringClass().isAssignableFrom(targetClass)) {
					return method.invoke(target, args);
				}

				return handler.invoke(proxy, method, args);
			}

		}, interfaces);
	}

	public static <T> T tracer(Object target) {
		return implementInterfaces(target, new InvocationHandler() {
			@Override
			public Object invoke(Object target, Method method, Object[] args) throws Throwable {
				Log.trace("intercepting", "method", method.getName(), "args", Arrays.toString(args));
				return method.invoke(target, args);
			}
		});
	}

	public static <T> T implement(InvocationHandler handler, Class<?>... classes) {
		return implement(new InterceptorProxy(U.str(classes)), handler, classes);
	}

	public static <T> T implementInterfaces(Object target, InvocationHandler handler) {
		return implement(target, handler, Cls.getImplementedInterfaces(target.getClass()));
	}

}