Java tutorial
/* * NOTICE: THE FILE HAS BEEN MODIFIED TO SUIT THE NEEDS OF THE PROJECT. * * 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.robobinding.util; import java.lang.reflect.Method; import java.lang.reflect.Modifier; /** * Migrated some of methods from * {@link org.apache.commons.lang3.reflect.MethodUtils}. * * @since 1.0 * @version $Revision: 1.0 $ * @author Cheng Wei */ public class MethodUtils { private MethodUtils() { super(); } /** * <p> * Returns an accessible method (that is, one that can be invoked via * reflection) with given name and parameters. If no such method can be * found, return <code>null</code>. This is just a convenient wrapper for * {@link #getAccessibleMethod(Method method)}. * </p> * * @param cls * get method from this class * @param methodName * get method with this name * @param parameterTypes * with these parameters types * @return The accessible method */ public static Method getAccessibleMethod(final Class<?> cls, final String methodName, final Class<?>... parameterTypes) { try { return getAccessibleMethod(cls.getMethod(methodName, parameterTypes)); } catch (final NoSuchMethodException e) { return null; } } /** * <p> * Returns an accessible method (that is, one that can be invoked via * reflection) that implements the specified Method. If no such method can * be found, return <code>null</code>. * </p> * * @param method * The method that we wish to call * @return The accessible method */ public static Method getAccessibleMethod(Method method) { if (!MemberUtils.isAccessible(method)) { return null; } // If the declaring class is public, we are done final Class<?> cls = method.getDeclaringClass(); if (Modifier.isPublic(cls.getModifiers())) { return method; } final String methodName = method.getName(); final Class<?>[] parameterTypes = method.getParameterTypes(); // Check the implemented interfaces and subinterfaces method = getAccessibleMethodFromInterfaceNest(cls, methodName, parameterTypes); // Check the superclass chain if (method == null) { method = getAccessibleMethodFromSuperclass(cls, methodName, parameterTypes); } return method; } /** * <p> * Returns an accessible method (that is, one that can be invoked via * reflection) by scanning through the superclasses. If no such method can * be found, return <code>null</code>. * </p> * * @param cls * Class to be checked * @param methodName * Method name of the method we wish to call * @param parameterTypes * The parameter type signatures * @return the accessible method or <code>null</code> if not found */ private static Method getAccessibleMethodFromSuperclass(final Class<?> cls, final String methodName, final Class<?>... parameterTypes) { Class<?> parentClass = cls.getSuperclass(); while (parentClass != null) { if (Modifier.isPublic(parentClass.getModifiers())) { try { return parentClass.getMethod(methodName, parameterTypes); } catch (final NoSuchMethodException e) { return null; } } parentClass = parentClass.getSuperclass(); } return null; } /** * <p> * Returns an accessible method (that is, one that can be invoked via * reflection) that implements the specified method, by scanning through all * implemented interfaces and subinterfaces. If no such method can be found, * return <code>null</code>. * </p> * * <p> * There isn't any good reason why this method must be private. It is * because there doesn't seem any reason why other classes should call this * rather than the higher level methods. * </p> * * @param cls * Parent class for the interfaces to be checked * @param methodName * Method name of the method we wish to call * @param parameterTypes * The parameter type signatures * @return the accessible method or <code>null</code> if not found */ private static Method getAccessibleMethodFromInterfaceNest(Class<?> cls, final String methodName, final Class<?>... parameterTypes) { Method method = null; // Search up the superclass chain for (; cls != null; cls = cls.getSuperclass()) { // Check the implemented interfaces of the parent class final Class<?>[] interfaces = cls.getInterfaces(); for (int i = 0; i < interfaces.length; i++) { // Is this interface public? if (!Modifier.isPublic(interfaces[i].getModifiers())) { continue; } // Does the method exist on this interface? try { method = interfaces[i].getDeclaredMethod(methodName, parameterTypes); } catch (final NoSuchMethodException e) { // NOPMD /* * Swallow, if no method is found after the loop then this * method returns null. */ } if (method != null) { break; } // Recursively check our parent interfaces method = getAccessibleMethodFromInterfaceNest(interfaces[i], methodName, parameterTypes); if (method != null) { break; } } } return method; } /** * <p> * Finds an accessible method that matches the given name and has compatible * parameters. Compatible parameters mean that every method parameter is * assignable from the given parameters. In other words, it finds a method * with the given name that will take the parameters given. * <p> * * <p> * This method is used by * {@link #invokeMethod(Object object, String methodName, Object[] args, Class[] parameterTypes)}. * * <p> * This method can match primitive parameter by passing in wrapper classes. * For example, a <code>Boolean</code> will match a primitive * <code>boolean</code> parameter. * * @param cls * find method in this class * @param methodName * find method with this name * @param parameterTypes * find method with most compatible parameters * @return The accessible method */ public static Method getMatchingAccessibleMethod(final Class<?> cls, final String methodName, final Class<?>... parameterTypes) { try { final Method method = cls.getMethod(methodName, parameterTypes); MemberUtils.setAccessibleWorkaround(method); return method; } catch (final NoSuchMethodException e) { // NOPMD - Swallow the // exception } // search through all methods Method bestMatch = null; final Method[] methods = cls.getMethods(); for (final Method method : methods) { // compare name and parameters if (method.getName().equals(methodName) && ClassUtils.isAssignable(parameterTypes, method.getParameterTypes(), true)) { // get accessible version of method final Method accessibleMethod = getAccessibleMethod(method); if (accessibleMethod != null && (bestMatch == null || MemberUtils.compareParameterTypes(accessibleMethod.getParameterTypes(), bestMatch.getParameterTypes(), parameterTypes) < 0)) { bestMatch = accessibleMethod; } } } if (bestMatch != null) { MemberUtils.setAccessibleWorkaround(bestMatch); } return bestMatch; } }