    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;
    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    /** The class to create */
    067    private final Class<T> iClassToInstantiate;
    068    /** The constructor parameter types */
    069    private final Class<?>[] iParamTypes;
    070    /** The constructor arguments */
    071    private final Object[] iArgs;
    072
    073    /** The constructor */
    074    private transient Constructor<T> iConstructor;
    075
    076    /**
    077     * Constructor that performs no validation.
    078     * Use {@code instantiateFactory} if you want that.
    079     *
    080     * @param classToInstantiate  the class to instantiate
    081     */
    082    public InstantiateFactory(final Class<T> classToInstantiate) {
    083        iClassToInstantiate = classToInstantiate;
    084        iParamTypes = null;
    085        iArgs = null;
    086        findConstructor();
    087    }
    088
    089    /**
    090     * Constructor that performs no validation.
    091     * Use {@code instantiateFactory} 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        iClassToInstantiate = classToInstantiate;
    099        iParamTypes = paramTypes.clone();
    100        iArgs = args.clone();
    101        findConstructor();
    102    }
    103
    104    /**
    105     * Creates an object using the stored constructor.
    106     *
    107     * @return the new object
    108     */
    109    @Override
    110    public T create() {
    111        // needed for post-serialization
    112        if (iConstructor == null) {
    113            findConstructor();
    114        }
    115
    116        try {
    117            return iConstructor.newInstance(iArgs);
    118        } catch (final InstantiationException ex) {
    119            throw new FunctorException("InstantiateFactory: InstantiationException", ex);
    120        } catch (final IllegalAccessException ex) {
    121            throw new FunctorException("InstantiateFactory: Constructor must be public", ex);
    122        } catch (final InvocationTargetException ex) {
    123            throw new FunctorException("InstantiateFactory: Constructor threw an exception", ex);
    124        }
    125    }
    126
    127    /**
    128     * Find the Constructor for the class specified.
    129     */
    130    private void findConstructor() {
    131        try {
    132            iConstructor = iClassToInstantiate.getConstructor(iParamTypes);
    133        } catch (final NoSuchMethodException ex) {
    134            throw new IllegalArgumentException("InstantiateFactory: The constructor must exist and be public ");
    135        }
    136    }
    137
    138}