    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.collections4.functors;
    018
    019import java.lang.reflect.InvocationTargetException;
    020import java.lang.reflect.Method;
    021
    022import org.apache.commons.collections4.FunctorException;
    023import org.apache.commons.collections4.Transformer;
    024
    025/**
    026 * Transformer implementation that creates a new object instance by reflection.
    027 * <p>
    028 * <b>WARNING:</b> from v4.1 onwards this class will <b>not</b> be serializable anymore
    029 * in order to prevent potential remote code execution exploits. Please refer to
    030 * <a href="https://issues.apache.org/jira/browse/COLLECTIONS-580">COLLECTIONS-580</a>
    031 * for more details.
    032 * </p>
    033 *
    034 * @since 3.0
    035 */
    036public class InvokerTransformer<I, O> implements Transformer<I, O> {
    037
    038    /** The method name to call */
    039    private final String iMethodName;
    040    /** The array of reflection parameter types */
    041    private final Class<?>[] iParamTypes;
    042    /** The array of reflection arguments */
    043    private final Object[] iArgs;
    044
    045    /**
    046     * Gets an instance of this transformer calling a specific method with no arguments.
    047     *
    048     * @param <I>  the input type
    049     * @param <O>  the output type
    050     * @param methodName  the method name to call
    051     * @return an invoker transformer
    052     * @throws NullPointerException if methodName is null
    053     * @since 3.1
    054     */
    055    public static <I, O> Transformer<I, O> invokerTransformer(final String methodName) {
    056        if (methodName == null) {
    057            throw new NullPointerException("The method to invoke must not be null");
    058        }
    059        return new InvokerTransformer<>(methodName);
    060    }
    061
    062    /**
    063     * Gets an instance of this transformer calling a specific method with specific values.
    064     *
    065     * @param <I>  the input type
    066     * @param <O>  the output type
    067     * @param methodName  the method name to call
    068     * @param paramTypes  the parameter types of the method
    069     * @param args  the arguments to pass to the method
    070     * @return an invoker transformer
    071     * @throws NullPointerException if methodName is null
    072     * @throws IllegalArgumentException if paramTypes does not match args
    073     */
    074    public static <I, O> Transformer<I, O> invokerTransformer(final String methodName, final Class<?>[] paramTypes,
    075                                                              final Object[] args) {
    076        if (methodName == null) {
    077            throw new NullPointerException("The method to invoke must not be null");
    078        }
    079        if (((paramTypes == null) && (args != null))
    080            || ((paramTypes != null) && (args == null))
    081            || ((paramTypes != null) && (args != null) && (paramTypes.length != args.length))) {
    082            throw new IllegalArgumentException("The parameter types must match the arguments");
    083        }
    084        if (paramTypes == null || paramTypes.length == 0) {
    085            return new InvokerTransformer<>(methodName);
    086        }
    087        return new InvokerTransformer<>(methodName, paramTypes, args);
    088    }
    089
    090    /**
    091     * Constructor for no arg instance.
    092     *
    093     * @param methodName  the method to call
    094     */
    095    private InvokerTransformer(final String methodName) {
    096        super();
    097        iMethodName = methodName;
    098        iParamTypes = null;
    099        iArgs = null;
    100    }
    101
    102    /**
    103     * Constructor that performs no validation.
    104     * Use <code>invokerTransformer</code> if you want that.
    105     * <p>
    106     * Note: from 4.0, the input parameters will be cloned
    107     *
    108     * @param methodName  the method to call
    109     * @param paramTypes  the constructor parameter types
    110     * @param args  the constructor arguments
    111     */
    112    public InvokerTransformer(final String methodName, final Class<?>[] paramTypes, final Object[] args) {
    113        super();
    114        iMethodName = methodName;
    115        iParamTypes = paramTypes != null ? paramTypes.clone() : null;
    116        iArgs = args != null ? args.clone() : null;
    117    }
    118
    119    /**
    120     * Transforms the input to result by invoking a method on the input.
    121     *
    122     * @param input  the input object to transform
    123     * @return the transformed result, null if null input
    124     */
    125    @Override
    126    @SuppressWarnings("unchecked")
    127    public O transform(final Object input) {
    128        if (input == null) {
    129            return null;
    130        }
    131        try {
    132            final Class<?> cls = input.getClass();
    133            final Method method = cls.getMethod(iMethodName, iParamTypes);
    134            return (O) method.invoke(input, iArgs);
    135        } catch (final NoSuchMethodException ex) {
    136            throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" +
    137                                       input.getClass() + "' does not exist");
    138        } catch (final IllegalAccessException ex) {
    139            throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" +
    140                                       input.getClass() + "' cannot be accessed");
    141        } catch (final InvocationTargetException ex) {
    142            throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" +
    143                                       input.getClass() + "' threw an exception", ex);
    144        }
    145    }
    146
    147}