org.robobinding.util.MethodUtils.java Source code

Java tutorial

Introduction

Here is the source code for org.robobinding.util.MethodUtils.java

Source

/*
 * 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;
    }
}