Java tutorial
/** * Copyright (C) 2010-2016 Gordon Fraser, Andrea Arcuri and EvoSuite * contributors * * This file is part of EvoSuite. * * EvoSuite is free software: you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published * by the Free Software Foundation, either version 3.0 of the License, or * (at your option) any later version. * * EvoSuite is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with EvoSuite. If not, see <http://www.gnu.org/licenses/>. */ package com.examples.with.different.packagename; import java.lang.reflect.InvocationHandler; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.lang.reflect.Proxy; import java.util.Arrays; import java.util.HashSet; import java.util.Set; import org.apache.commons.lang3.reflect.MethodUtils; /** * Snippet from Lang project * (org.apache.commons.lang3.event.EventUtils) */ public class ClassPublicInterface { public static <L> void addEventListener(final Object eventSource, final Class<L> listenerType, final L listener) { try { MethodUtils.invokeMethod(eventSource, "add" + listenerType.getSimpleName(), listener); } catch (final NoSuchMethodException e) { throw new IllegalArgumentException("Class " + eventSource.getClass().getName() + " does not have a public add" + listenerType.getSimpleName() + " method which takes a parameter of type " + listenerType.getName() + "."); } catch (final IllegalAccessException e) { throw new IllegalArgumentException("Class " + eventSource.getClass().getName() + " does not have an accessible add" + listenerType.getSimpleName() + " method which takes a parameter of type " + listenerType.getName() + "."); } catch (final InvocationTargetException e) { throw new RuntimeException("Unable to add listener.", e.getCause()); } } public static <L> void bindEventsToMethod(final Object target, final String methodName, final Object eventSource, final Class<L> listenerType, final String... eventTypes) { final L listener = listenerType.cast(Proxy.newProxyInstance(target.getClass().getClassLoader(), new Class[] { listenerType }, new EventBindingInvocationHandler(target, methodName, eventTypes))); addEventListener(eventSource, listenerType, listener); } private static class EventBindingInvocationHandler implements InvocationHandler { private final Object target; private final String methodName; private final Set<String> eventTypes; /** * Creates a new instance of {@code EventBindingInvocationHandler}. * * @param target the target object for method invocations * @param methodName the name of the method to be invoked * @param eventTypes the names of the supported event types */ EventBindingInvocationHandler(final Object target, final String methodName, final String[] eventTypes) { this.target = target; this.methodName = methodName; this.eventTypes = new HashSet<String>(Arrays.asList(eventTypes)); } /** * Handles a method invocation on the proxy object. * * @param proxy the proxy instance * @param method the method to be invoked * @param parameters the parameters for the method invocation * @return the result of the method call * @throws Throwable if an error occurs */ @Override public Object invoke(final Object proxy, final Method method, final Object[] parameters) throws Throwable { if (eventTypes.isEmpty() || eventTypes.contains(method.getName())) { if (hasMatchingParametersMethod(method)) { return MethodUtils.invokeMethod(target, methodName, parameters); } return MethodUtils.invokeMethod(target, methodName); } return null; } /** * Checks whether a method for the passed in parameters can be found. * * @param method the listener method invoked * @return a flag whether the parameters could be matched */ private boolean hasMatchingParametersMethod(final Method method) { return MethodUtils.getAccessibleMethod(target.getClass(), methodName, method.getParameterTypes()) != null; } } }