1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.collections4.functors;
18
19 import java.lang.reflect.Constructor;
20 import java.lang.reflect.InvocationTargetException;
21
22 import org.apache.commons.collections4.FunctorException;
23 import org.apache.commons.collections4.Transformer;
24
25 /**
26 * Transformer implementation that creates a new object instance by reflection.
27 * <p>
28 * <b>WARNING:</b> from v4.1 onwards this class will <b>not</b> be serializable anymore
29 * in order to prevent potential remote code execution exploits. Please refer to
30 * <a href="https://issues.apache.org/jira/browse/COLLECTIONS-580">COLLECTIONS-580</a>
31 * for more details.
32 * </p>
33 *
34 * @since 3.0
35 */
36 public class InstantiateTransformer<T> implements Transformer<Class<? extends T>, T> {
37
38 /** Singleton instance that uses the no arg constructor */
39 @SuppressWarnings("rawtypes")
40 private static final Transformer NO_ARG_INSTANCE = new InstantiateTransformer<>();
41
42 /**
43 * Gets a typed no-arg instance.
44 *
45 * @param <T> the type of the objects to be created
46 * @return Transformer<Class<? extends T>, T>
47 */
48 public static <T> Transformer<Class<? extends T>, T> instantiateTransformer() {
49 return NO_ARG_INSTANCE;
50 }
51 /**
52 * Transformer method that performs validation.
53 *
54 * @param <T> the type of the objects to be created
55 * @param paramTypes the constructor parameter types
56 * @param args the constructor arguments
57 * @return an instantiate transformer
58 * @throws IllegalArgumentException if paramTypes does not match args
59 */
60 public static <T> Transformer<Class<? extends T>, T> instantiateTransformer(final Class<?>[] paramTypes,
61 final Object[] args) {
62 if (paramTypes == null && args != null
63 || paramTypes != null && args == null
64 || paramTypes != null && args != null && paramTypes.length != args.length) {
65 throw new IllegalArgumentException("Parameter types must match the arguments");
66 }
67
68 if (paramTypes == null || paramTypes.length == 0) {
69 return new InstantiateTransformer<>();
70 }
71 return new InstantiateTransformer<>(paramTypes, args);
72 }
73
74 /** The constructor parameter types */
75 private final Class<?>[] iParamTypes;
76
77 /** The constructor arguments */
78 private final Object[] iArgs;
79
80 /**
81 * Constructor for no arg instance.
82 */
83 private InstantiateTransformer() {
84 iParamTypes = null;
85 iArgs = null;
86 }
87
88 /**
89 * Constructor that performs no validation.
90 * Use {@code instantiateTransformer} if you want that.
91 * <p>
92 * Note: from 4.0, the input parameters will be cloned
93 *
94 * @param paramTypes the constructor parameter types
95 * @param args the constructor arguments
96 */
97 public InstantiateTransformer(final Class<?>[] paramTypes, final Object[] args) {
98 iParamTypes = paramTypes != null ? paramTypes.clone() : null;
99 iArgs = args != null ? args.clone() : null;
100 }
101
102 /**
103 * Transforms the input Class object to a result by instantiation.
104 *
105 * @param input the input object to transform
106 * @return the transformed result
107 */
108 @Override
109 public T transform(final Class<? extends T> input) {
110 try {
111 if (input == null) {
112 throw new FunctorException(
113 "InstantiateTransformer: Input object was not an instanceof Class, it was a null object");
114 }
115 final Constructor<? extends T> con = input.getConstructor(iParamTypes);
116 return con.newInstance(iArgs);
117 } catch (final NoSuchMethodException ex) {
118 throw new FunctorException("InstantiateTransformer: The constructor must exist and be public ");
119 } catch (final InstantiationException ex) {
120 throw new FunctorException("InstantiateTransformer: InstantiationException", ex);
121 } catch (final IllegalAccessException ex) {
122 throw new FunctorException("InstantiateTransformer: Constructor must be public", ex);
123 } catch (final InvocationTargetException ex) {
124 throw new FunctorException("InstantiateTransformer: Constructor threw an exception", ex);
125 }
126 }
127
128 }