    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 *      https://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;
    021import java.util.Objects;
    022
    023import org.apache.commons.collections4.FunctorException;
    024import org.apache.commons.collections4.Transformer;
    025
    026/**
    027 * Transformer implementation that creates a new object instance by reflection.
    028 * <p>
    029 * <strong>WARNING:</strong> from v4.1 onwards this class will <strong>not</strong> be serializable anymore
    030 * in order to prevent potential remote code execution exploits. Please refer to
    031 * <a href="https://issues.apache.org/jira/browse/COLLECTIONS-580">COLLECTIONS-580</a>
    032 * for more details.
    033 * </p>
    034 *
    035 * @param <T> The type of the input to the function.
    036 * @param <R> The type of the result of the function.
    037 * @since 3.0
    038 */
    039public class InvokerTransformer<T, R> implements Transformer<T, R> {
    040
    041    /**
    042     * Gets an instance of this transformer calling a specific method with no arguments.
    043     *
    044     * @param <I>  the input type
    045     * @param <O>  the output type
    046     * @param methodName  The method name to call
    047     * @return An invoker transformer
    048     * @throws NullPointerException if methodName is null
    049     * @since 3.1
    050     */
    051    public static <I, O> Transformer<I, O> invokerTransformer(final String methodName) {
    052        return new InvokerTransformer<>(Objects.requireNonNull(methodName, "methodName"));
    053    }
    054
    055    /**
    056     * Gets an instance of this transformer calling a specific method with specific values.
    057     *
    058     * @param <I>  the input type
    059     * @param <O>  the output type
    060     * @param methodName  The method name to call
    061     * @param paramTypes  The parameter types of the method
    062     * @param args  The arguments to pass to the method
    063     * @return An invoker transformer
    064     * @throws NullPointerException if methodName is null
    065     * @throws IllegalArgumentException if paramTypes does not match args
    066     */
    067    public static <I, O> Transformer<I, O> invokerTransformer(final String methodName, final Class<?>[] paramTypes,
    068                                                              final Object[] args) {
    069        Objects.requireNonNull(methodName, "methodName");
    070        if (paramTypes == null && args != null
    071            || paramTypes != null && args == null
    072            || paramTypes != null && args != null && paramTypes.length != args.length) {
    073            throw new IllegalArgumentException("The parameter types must match the arguments");
    074        }
    075        if (paramTypes == null || paramTypes.length == 0) {
    076            return new InvokerTransformer<>(methodName);
    077        }
    078        return new InvokerTransformer<>(methodName, paramTypes, args);
    079    }
    080
    081    /** The method name to call */
    082    private final String iMethodName;
    083
    084    /** The array of reflection parameter types */
    085    private final Class<?>[] iParamTypes;
    086
    087    /** The array of reflection arguments */
    088    private final Object[] iArgs;
    089
    090    /**
    091     * Constructor for no arg instance.
    092     *
    093     * @param methodName  The method to call
    094     */
    095    private InvokerTransformer(final String methodName) {
    096        iMethodName = methodName;
    097        iParamTypes = null;
    098        iArgs = null;
    099    }
    100
    101    /**
    102     * Constructor that performs no validation.
    103     * Use {@code invokerTransformer} 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        iMethodName = methodName;
    113        iParamTypes = paramTypes != null ? paramTypes.clone() : null;
    114        iArgs = args != null ? args.clone() : null;
    115    }
    116
    117    /**
    118     * Transforms the input to result by invoking a method on the input.
    119     *
    120     * @param input  The input object to transform
    121     * @return The transformed result, null if null input
    122     */
    123    @Override
    124    @SuppressWarnings("unchecked")
    125    public R transform(final Object input) {
    126        if (input == null) {
    127            return null;
    128        }
    129        try {
    130            final Class<?> cls = input.getClass();
    131            final Method method = cls.getMethod(iMethodName, iParamTypes);
    132            return (R) method.invoke(input, iArgs);
    133        } catch (final NoSuchMethodException ex) {
    134            throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" +
    135                                       input.getClass() + "' does not exist");
    136        } catch (final IllegalAccessException ex) {
    137            throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" +
    138                                       input.getClass() + "' cannot be accessed");
    139        } catch (final InvocationTargetException ex) {
    140            throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" +
    141                                       input.getClass() + "' threw an exception", ex);
    142        }
    143    }
    144
    145}