    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.Constructor;
    020import java.lang.reflect.InvocationTargetException;
    021import java.util.Objects;
    022
    023import org.apache.commons.collections4.Factory;
    024import org.apache.commons.collections4.FunctorException;
    025
    026/**
    027 * Factory 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 results supplied by this supplier.
    036 * @since 3.0
    037 */
    038public class InstantiateFactory<T> implements Factory<T> {
    039
    040    /**
    041     * Factory method that performs validation.
    042     *
    043     * @param <T>  the type the factory creates
    044     * @param classToInstantiate  The class to instantiate, not null
    045     * @param paramTypes  The constructor parameter types, cloned
    046     * @param args  The constructor arguments, cloned
    047     * @return A new instantiate factory
    048     * @throws NullPointerException if classToInstantiate is null
    049     * @throws IllegalArgumentException if paramTypes does not match args
    050     */
    051    public static <T> Factory<T> instantiateFactory(final Class<T> classToInstantiate,
    052                                                    final Class<?>[] paramTypes,
    053                                                    final Object[] args) {
    054        Objects.requireNonNull(classToInstantiate, "classToInstantiate");
    055        if (paramTypes == null && args != null
    056            || paramTypes != null && args == null
    057            || paramTypes != null && args != null && paramTypes.length != args.length) {
    058            throw new IllegalArgumentException("Parameter types must match the arguments");
    059        }
    060
    061        if (paramTypes == null || paramTypes.length == 0) {
    062            return new InstantiateFactory<>(classToInstantiate);
    063        }
    064        return new InstantiateFactory<>(classToInstantiate, paramTypes, args);
    065    }
    066
    067    /** The class to create */
    068    private final Class<T> iClassToInstantiate;
    069
    070    /** The constructor parameter types */
    071    private final Class<?>[] iParamTypes;
    072
    073    /** The constructor arguments */
    074    private final Object[] iArgs;
    075
    076    /** The constructor */
    077    private transient Constructor<T> iConstructor;
    078
    079    /**
    080     * Constructor that performs no validation.
    081     * Use {@code instantiateFactory} if you want that.
    082     *
    083     * @param classToInstantiate  The class to instantiate
    084     */
    085    public InstantiateFactory(final Class<T> classToInstantiate) {
    086        iClassToInstantiate = classToInstantiate;
    087        iParamTypes = null;
    088        iArgs = null;
    089        findConstructor();
    090    }
    091
    092    /**
    093     * Constructor that performs no validation.
    094     * Use {@code instantiateFactory} if you want that.
    095     *
    096     * @param classToInstantiate  The class to instantiate
    097     * @param paramTypes  The constructor parameter types, cloned
    098     * @param args  The constructor arguments, cloned
    099     */
    100    public InstantiateFactory(final Class<T> classToInstantiate, final Class<?>[] paramTypes, final Object[] args) {
    101        iClassToInstantiate = classToInstantiate;
    102        iParamTypes = paramTypes.clone();
    103        iArgs = args.clone();
    104        findConstructor();
    105    }
    106
    107    /**
    108     * Creates an object using the stored constructor.
    109     *
    110     * @return The new object
    111     */
    112    @Override
    113    public T create() {
    114        // needed for post-serialization
    115        if (iConstructor == null) {
    116            findConstructor();
    117        }
    118
    119        try {
    120            return iConstructor.newInstance(iArgs);
    121        } catch (final InstantiationException ex) {
    122            throw new FunctorException("InstantiateFactory: InstantiationException", ex);
    123        } catch (final IllegalAccessException ex) {
    124            throw new FunctorException("InstantiateFactory: Constructor must be public", ex);
    125        } catch (final InvocationTargetException ex) {
    126            throw new FunctorException("InstantiateFactory: Constructor threw an exception", ex);
    127        }
    128    }
    129
    130    /**
    131     * Find the Constructor for the class specified.
    132     */
    133    private void findConstructor() {
    134        try {
    135            iConstructor = iClassToInstantiate.getConstructor(iParamTypes);
    136        } catch (final NoSuchMethodException ex) {
    137            throw new IllegalArgumentException("InstantiateFactory: The constructor must exist and be public ");
    138        }
    139    }
    140
    141}