    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 * </p>
    033 *
    034 * @since 3.0
    035 */
    036public class InstantiateFactory<T> implements Factory<T> {
    037
    038    /** The class to create */
    039    private final Class<T> iClassToInstantiate;
    040    /** The constructor parameter types */
    041    private final Class<?>[] iParamTypes;
    042    /** The constructor arguments */
    043    private final Object[] iArgs;
    044    /** The constructor */
    045    private transient Constructor<T> iConstructor = null;
    046
    047    /**
    048     * Factory method that performs validation.
    049     *
    050     * @param <T>  the type the factory creates
    051     * @param classToInstantiate  the class to instantiate, not null
    052     * @param paramTypes  the constructor parameter types, cloned
    053     * @param args  the constructor arguments, cloned
    054     * @return a new instantiate factory
    055     * @throws NullPointerException if classToInstantiate is null
    056     * @throws IllegalArgumentException if paramTypes does not match args
    057     */
    058    public static <T> Factory<T> instantiateFactory(final Class<T> classToInstantiate,
    059                                                    final Class<?>[] paramTypes,
    060                                                    final Object[] args) {
    061        if (classToInstantiate == null) {
    062            throw new NullPointerException("Class to instantiate must not be null");
    063        }
    064        if (paramTypes == null && args != null
    065            || paramTypes != null && args == null
    066            || paramTypes != null && args != null && paramTypes.length != args.length) {
    067            throw new IllegalArgumentException("Parameter types must match the arguments");
    068        }
    069
    070        if (paramTypes == null || paramTypes.length == 0) {
    071            return new InstantiateFactory<>(classToInstantiate);
    072        }
    073        return new InstantiateFactory<>(classToInstantiate, paramTypes, args);
    074    }
    075
    076    /**
    077     * Constructor that performs no validation.
    078     * Use <code>instantiateFactory</code> if you want that.
    079     *
    080     * @param classToInstantiate  the class to instantiate
    081     */
    082    public InstantiateFactory(final Class<T> classToInstantiate) {
    083        super();
    084        iClassToInstantiate = classToInstantiate;
    085        iParamTypes = null;
    086        iArgs = null;
    087        findConstructor();
    088    }
    089
    090    /**
    091     * Constructor that performs no validation.
    092     * Use <code>instantiateFactory</code> if you want that.
    093     *
    094     * @param classToInstantiate  the class to instantiate
    095     * @param paramTypes  the constructor parameter types, cloned
    096     * @param args  the constructor arguments, cloned
    097     */
    098    public InstantiateFactory(final Class<T> classToInstantiate, final Class<?>[] paramTypes, final Object[] args) {
    099        super();
    100        iClassToInstantiate = classToInstantiate;
    101        iParamTypes = paramTypes.clone();
    102        iArgs = args.clone();
    103        findConstructor();
    104    }
    105
    106    /**
    107     * Find the Constructor for the class specified.
    108     */
    109    private void findConstructor() {
    110        try {
    111            iConstructor = iClassToInstantiate.getConstructor(iParamTypes);
    112        } catch (final NoSuchMethodException ex) {
    113            throw new IllegalArgumentException("InstantiateFactory: The constructor must exist and be public ");
    114        }
    115    }
    116
    117    /**
    118     * Creates an object using the stored constructor.
    119     *
    120     * @return the new object
    121     */
    122    @Override
    123    public T create() {
    124        // needed for post-serialization
    125        if (iConstructor == null) {
    126            findConstructor();
    127        }
    128
    129        try {
    130            return iConstructor.newInstance(iArgs);
    131        } catch (final InstantiationException ex) {
    132            throw new FunctorException("InstantiateFactory: InstantiationException", ex);
    133        } catch (final IllegalAccessException ex) {
    134            throw new FunctorException("InstantiateFactory: Constructor must be public", ex);
    135        } catch (final InvocationTargetException ex) {
    136            throw new FunctorException("InstantiateFactory: Constructor threw an exception", ex);
    137        }
    138    }
    139
    140}