    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.Constructor;
    020import java.lang.reflect.InvocationTargetException;
    021
    022import org.apache.commons.collections4.Factory;
    023import org.apache.commons.collections4.FunctorException;
    024
    025/**
    026 * Factory 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 InstantiateFactory<T> implements Factory<T> {
    036
    037    /** The class to create */
    038    private final Class<T> iClassToInstantiate;
    039    /** The constructor parameter types */
    040    private final Class<?>[] iParamTypes;
    041    /** The constructor arguments */
    042    private final Object[] iArgs;
    043    /** The constructor */
    044    private transient Constructor<T> iConstructor = null;
    045
    046    /**
    047     * Factory method that performs validation.
    048     *
    049     * @param <T>  the type the factory creates
    050     * @param classToInstantiate  the class to instantiate, not null
    051     * @param paramTypes  the constructor parameter types, cloned
    052     * @param args  the constructor arguments, cloned
    053     * @return a new instantiate factory
    054     * @throws NullPointerException if classToInstantiate is null
    055     * @throws IllegalArgumentException if paramTypes does not match args
    056     */
    057    public static <T> Factory<T> instantiateFactory(final Class<T> classToInstantiate,
    058                                                    final Class<?>[] paramTypes,
    059                                                    final Object[] args) {
    060        if (classToInstantiate == null) {
    061            throw new NullPointerException("Class to instantiate must not be null");
    062        }
    063        if (paramTypes == null && args != null
    064            || paramTypes != null && args == null
    065            || paramTypes != null && args != null && paramTypes.length != args.length) {
    066            throw new IllegalArgumentException("Parameter types must match the arguments");
    067        }
    068
    069        if (paramTypes == null || paramTypes.length == 0) {
    070            return new InstantiateFactory<>(classToInstantiate);
    071        }
    072        return new InstantiateFactory<>(classToInstantiate, paramTypes, args);
    073    }
    074
    075    /**
    076     * Constructor that performs no validation.
    077     * Use <code>instantiateFactory</code> if you want that.
    078     *
    079     * @param classToInstantiate  the class to instantiate
    080     */
    081    public InstantiateFactory(final Class<T> classToInstantiate) {
    082        super();
    083        iClassToInstantiate = classToInstantiate;
    084        iParamTypes = null;
    085        iArgs = null;
    086        findConstructor();
    087    }
    088
    089    /**
    090     * Constructor that performs no validation.
    091     * Use <code>instantiateFactory</code> if you want that.
    092     *
    093     * @param classToInstantiate  the class to instantiate
    094     * @param paramTypes  the constructor parameter types, cloned
    095     * @param args  the constructor arguments, cloned
    096     */
    097    public InstantiateFactory(final Class<T> classToInstantiate, final Class<?>[] paramTypes, final Object[] args) {
    098        super();
    099        iClassToInstantiate = classToInstantiate;
    100        iParamTypes = paramTypes.clone();
    101        iArgs = args.clone();
    102        findConstructor();
    103    }
    104
    105    /**
    106     * Find the Constructor for the class specified.
    107     */
    108    private void findConstructor() {
    109        try {
    110            iConstructor = iClassToInstantiate.getConstructor(iParamTypes);
    111        } catch (final NoSuchMethodException ex) {
    112            throw new IllegalArgumentException("InstantiateFactory: The constructor must exist and be public ");
    113        }
    114    }
    115
    116    /**
    117     * Creates an object using the stored constructor.
    118     *
    119     * @return the new object
    120     */
    121    @Override
    122    public T create() {
    123        // needed for post-serialization
    124        if (iConstructor == null) {
    125            findConstructor();
    126        }
    127
    128        try {
    129            return iConstructor.newInstance(iArgs);
    130        } catch (final InstantiationException ex) {
    131            throw new FunctorException("InstantiateFactory: InstantiationException", ex);
    132        } catch (final IllegalAccessException ex) {
    133            throw new FunctorException("InstantiateFactory: Constructor must be public", ex);
    134        } catch (final InvocationTargetException ex) {
    135            throw new FunctorException("InstantiateFactory: Constructor threw an exception", ex);
    136        }
    137    }
    138
    139}