    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 *
    033 * @since 3.0
    034 */
    035public class InvokerTransformer<I, O> implements Transformer<I, O> {
    036
    037    /** The method name to call */
    038    private final String iMethodName;
    039    /** The array of reflection parameter types */
    040    private final Class<?>[] iParamTypes;
    041    /** The array of reflection arguments */
    042    private final Object[] iArgs;
    043
    044    /**
    045     * Gets an instance of this transformer calling a specific method with no arguments.
    046     *
    047     * @param <I>  the input type
    048     * @param <O>  the output type
    049     * @param methodName  the method name to call
    050     * @return an invoker transformer
    051     * @throws NullPointerException if methodName is null
    052     * @since 3.1
    053     */
    054    public static <I, O> Transformer<I, O> invokerTransformer(final String methodName) {
    055        if (methodName == null) {
    056            throw new NullPointerException("The method to invoke must not be null");
    057        }
    058        return new InvokerTransformer<>(methodName);
    059    }
    060
    061    /**
    062     * Gets an instance of this transformer calling a specific method with specific values.
    063     *
    064     * @param <I>  the input type
    065     * @param <O>  the output type
    066     * @param methodName  the method name to call
    067     * @param paramTypes  the parameter types of the method
    068     * @param args  the arguments to pass to the method
    069     * @return an invoker transformer
    070     * @throws NullPointerException if methodName is null
    071     * @throws IllegalArgumentException if paramTypes does not match args
    072     */
    073    public static <I, O> Transformer<I, O> invokerTransformer(final String methodName, final Class<?>[] paramTypes,
    074                                                              final Object[] args) {
    075        if (methodName == null) {
    076            throw new NullPointerException("The method to invoke must not be null");
    077        }
    078        if (((paramTypes == null) && (args != null))
    079            || ((paramTypes != null) && (args == null))
    080            || ((paramTypes != null) && (args != null) && (paramTypes.length != args.length))) {
    081            throw new IllegalArgumentException("The parameter types must match the arguments");
    082        }
    083        if (paramTypes == null || paramTypes.length == 0) {
    084            return new InvokerTransformer<>(methodName);
    085        }
    086        return new InvokerTransformer<>(methodName, paramTypes, args);
    087    }
    088
    089    /**
    090     * Constructor for no arg instance.
    091     *
    092     * @param methodName  the method to call
    093     */
    094    private InvokerTransformer(final String methodName) {
    095        super();
    096        iMethodName = methodName;
    097        iParamTypes = null;
    098        iArgs = null;
    099    }
    100
    101    /**
    102     * Constructor that performs no validation.
    103     * Use <code>invokerTransformer</code> if you want that.
    104     * <p>
    105     * Note: from 4.0, the input parameters will be cloned
    106     *
    107     * @param methodName  the method to call
    108     * @param paramTypes  the constructor parameter types
    109     * @param args  the constructor arguments
    110     */
    111    public InvokerTransformer(final String methodName, final Class<?>[] paramTypes, final Object[] args) {
    112        super();
    113        iMethodName = methodName;
    114        iParamTypes = paramTypes != null ? paramTypes.clone() : null;
    115        iArgs = args != null ? args.clone() : null;
    116    }
    117
    118    /**
    119     * Transforms the input to result by invoking a method on the input.
    120     *
    121     * @param input  the input object to transform
    122     * @return the transformed result, null if null input
    123     */
    124    @Override
    125    @SuppressWarnings("unchecked")
    126    public O transform(final Object input) {
    127        if (input == null) {
    128            return null;
    129        }
    130        try {
    131            final Class<?> cls = input.getClass();
    132            final Method method = cls.getMethod(iMethodName, iParamTypes);
    133            return (O) method.invoke(input, iArgs);
    134        } catch (final NoSuchMethodException ex) {
    135            throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" +
    136                                       input.getClass() + "' does not exist");
    137        } catch (final IllegalAccessException ex) {
    138            throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" +
    139                                       input.getClass() + "' cannot be accessed");
    140        } catch (final InvocationTargetException ex) {
    141            throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" +
    142                                       input.getClass() + "' threw an exception", ex);
    143        }
    144    }
    145
    146}