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.InvocationTargetException;
020import java.lang.reflect.Method;
021import java.util.Objects;
022
023import org.apache.commons.collections4.FunctorException;
024import org.apache.commons.collections4.Transformer;
025
026/**
027 * Transformer 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 InvokerTransformer<I, O> implements Transformer<I, O> {
038
039    /**
040     * Gets an instance of this transformer calling a specific method with no arguments.
041     *
042     * @param <I>  the input type
043     * @param <O>  the output type
044     * @param methodName  the method name to call
045     * @return an invoker transformer
046     * @throws NullPointerException if methodName is null
047     * @since 3.1
048     */
049    public static <I, O> Transformer<I, O> invokerTransformer(final String methodName) {
050        return new InvokerTransformer<>(Objects.requireNonNull(methodName, "methodName"));
051    }
052    /**
053     * Gets an instance of this transformer calling a specific method with specific values.
054     *
055     * @param <I>  the input type
056     * @param <O>  the output type
057     * @param methodName  the method name to call
058     * @param paramTypes  the parameter types of the method
059     * @param args  the arguments to pass to the method
060     * @return an invoker transformer
061     * @throws NullPointerException if methodName is null
062     * @throws IllegalArgumentException if paramTypes does not match args
063     */
064    public static <I, O> Transformer<I, O> invokerTransformer(final String methodName, final Class<?>[] paramTypes,
065                                                              final Object[] args) {
066        Objects.requireNonNull(methodName, "methodName");
067        if (paramTypes == null && args != null
068            || paramTypes != null && args == null
069            || paramTypes != null && args != null && paramTypes.length != args.length) {
070            throw new IllegalArgumentException("The parameter types must match the arguments");
071        }
072        if (paramTypes == null || paramTypes.length == 0) {
073            return new InvokerTransformer<>(methodName);
074        }
075        return new InvokerTransformer<>(methodName, paramTypes, args);
076    }
077    /** The method name to call */
078    private final String iMethodName;
079
080    /** The array of reflection parameter types */
081    private final Class<?>[] iParamTypes;
082
083    /** The array of reflection arguments */
084    private final Object[] iArgs;
085
086    /**
087     * Constructor for no arg instance.
088     *
089     * @param methodName  the method to call
090     */
091    private InvokerTransformer(final String methodName) {
092        iMethodName = methodName;
093        iParamTypes = null;
094        iArgs = null;
095    }
096
097    /**
098     * Constructor that performs no validation.
099     * Use {@code invokerTransformer} if you want that.
100     * <p>
101     * Note: from 4.0, the input parameters will be cloned
102     *
103     * @param methodName  the method to call
104     * @param paramTypes  the constructor parameter types
105     * @param args  the constructor arguments
106     */
107    public InvokerTransformer(final String methodName, final Class<?>[] paramTypes, final Object[] args) {
108        iMethodName = methodName;
109        iParamTypes = paramTypes != null ? paramTypes.clone() : null;
110        iArgs = args != null ? args.clone() : null;
111    }
112
113    /**
114     * Transforms the input to result by invoking a method on the input.
115     *
116     * @param input  the input object to transform
117     * @return the transformed result, null if null input
118     */
119    @Override
120    @SuppressWarnings("unchecked")
121    public O transform(final Object input) {
122        if (input == null) {
123            return null;
124        }
125        try {
126            final Class<?> cls = input.getClass();
127            final Method method = cls.getMethod(iMethodName, iParamTypes);
128            return (O) method.invoke(input, iArgs);
129        } catch (final NoSuchMethodException ex) {
130            throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" +
131                                       input.getClass() + "' does not exist");
132        } catch (final IllegalAccessException ex) {
133            throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" +
134                                       input.getClass() + "' cannot be accessed");
135        } catch (final InvocationTargetException ex) {
136            throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" +
137                                       input.getClass() + "' threw an exception", ex);
138        }
139    }
140
141}