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 * <b>WARNING:</b> from v4.1 onwards this class will <b>not</b> 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 * @since 3.0
036 */
037public class InstantiateFactory<T> implements Factory<T> {
038
039    /**
040     * Factory method that performs validation.
041     *
042     * @param <T>  the type the factory creates
043     * @param classToInstantiate  the class to instantiate, not null
044     * @param paramTypes  the constructor parameter types, cloned
045     * @param args  the constructor arguments, cloned
046     * @return a new instantiate factory
047     * @throws NullPointerException if classToInstantiate is null
048     * @throws IllegalArgumentException if paramTypes does not match args
049     */
050    public static <T> Factory<T> instantiateFactory(final Class<T> classToInstantiate,
051                                                    final Class<?>[] paramTypes,
052                                                    final Object[] args) {
053        Objects.requireNonNull(classToInstantiate, "classToInstantiate");
054        if (paramTypes == null && args != null
055            || paramTypes != null && args == null
056            || paramTypes != null && args != null && paramTypes.length != args.length) {
057            throw new IllegalArgumentException("Parameter types must match the arguments");
058        }
059
060        if (paramTypes == null || paramTypes.length == 0) {
061            return new InstantiateFactory<>(classToInstantiate);
062        }
063        return new InstantiateFactory<>(classToInstantiate, paramTypes, args);
064    }
065    /** The class to create */
066    private final Class<T> iClassToInstantiate;
067    /** The constructor parameter types */
068    private final Class<?>[] iParamTypes;
069    /** The constructor arguments */
070    private final Object[] iArgs;
071
072    /** The constructor */
073    private transient Constructor<T> iConstructor;
074
075    /**
076     * Constructor that performs no validation.
077     * Use {@code instantiateFactory} if you want that.
078     *
079     * @param classToInstantiate  the class to instantiate
080     */
081    public InstantiateFactory(final Class<T> classToInstantiate) {
082        iClassToInstantiate = classToInstantiate;
083        iParamTypes = null;
084        iArgs = null;
085        findConstructor();
086    }
087
088    /**
089     * Constructor that performs no validation.
090     * Use {@code instantiateFactory} if you want that.
091     *
092     * @param classToInstantiate  the class to instantiate
093     * @param paramTypes  the constructor parameter types, cloned
094     * @param args  the constructor arguments, cloned
095     */
096    public InstantiateFactory(final Class<T> classToInstantiate, final Class<?>[] paramTypes, final Object[] args) {
097        iClassToInstantiate = classToInstantiate;
098        iParamTypes = paramTypes.clone();
099        iArgs = args.clone();
100        findConstructor();
101    }
102
103    /**
104     * Creates an object using the stored constructor.
105     *
106     * @return the new object
107     */
108    @Override
109    public T create() {
110        // needed for post-serialization
111        if (iConstructor == null) {
112            findConstructor();
113        }
114
115        try {
116            return iConstructor.newInstance(iArgs);
117        } catch (final InstantiationException ex) {
118            throw new FunctorException("InstantiateFactory: InstantiationException", ex);
119        } catch (final IllegalAccessException ex) {
120            throw new FunctorException("InstantiateFactory: Constructor must be public", ex);
121        } catch (final InvocationTargetException ex) {
122            throw new FunctorException("InstantiateFactory: Constructor threw an exception", ex);
123        }
124    }
125
126    /**
127     * Find the Constructor for the class specified.
128     */
129    private void findConstructor() {
130        try {
131            iConstructor = iClassToInstantiate.getConstructor(iParamTypes);
132        } catch (final NoSuchMethodException ex) {
133            throw new IllegalArgumentException("InstantiateFactory: The constructor must exist and be public ");
134        }
135    }
136
137}