/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
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package org.apache.commons.collections4.functors;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

import org.apache.commons.collections4.FunctorException;
import org.apache.commons.collections4.Transformer;

Transformer implementation that creates a new object instance by reflection.

WARNING: from v4.1 onwards this class will not be serializable anymore in order to prevent potential remote code execution exploits. Please refer to COLLECTIONS-580 for more details.

Since:3.0
/** * Transformer implementation that creates a new object instance by reflection. * <p> * <b>WARNING:</b> from v4.1 onwards this class will <b>not</b> be serializable anymore * in order to prevent potential remote code execution exploits. Please refer to * <a href="https://issues.apache.org/jira/browse/COLLECTIONS-580">COLLECTIONS-580</a> * for more details. * * @since 3.0 */
public class InstantiateTransformer<T> implements Transformer<Class<? extends T>, T> {
Singleton instance that uses the no arg constructor
/** Singleton instance that uses the no arg constructor */
@SuppressWarnings("rawtypes") private static final Transformer NO_ARG_INSTANCE = new InstantiateTransformer<>();
The constructor parameter types
/** The constructor parameter types */
private final Class<?>[] iParamTypes;
The constructor arguments
/** The constructor arguments */
private final Object[] iArgs;
Get a typed no-arg instance.
Type parameters:
  • <T> – the type of the objects to be created
Returns:Transformer<Class<? extends T>, T>
/** * Get a typed no-arg instance. * * @param <T> the type of the objects to be created * @return Transformer&lt;Class&lt;? extends T&gt;, T&gt; */
@SuppressWarnings("unchecked") public static <T> Transformer<Class<? extends T>, T> instantiateTransformer() { return NO_ARG_INSTANCE; }
Transformer method that performs validation.
Params:
  • paramTypes – the constructor parameter types
  • args – the constructor arguments
Type parameters:
  • <T> – the type of the objects to be created
Throws:
Returns:an instantiate transformer
/** * Transformer method that performs validation. * * @param <T> the type of the objects to be created * @param paramTypes the constructor parameter types * @param args the constructor arguments * @return an instantiate transformer * @throws IllegalArgumentException if paramTypes does not match args */
public static <T> Transformer<Class<? extends T>, T> instantiateTransformer(final Class<?>[] paramTypes, final Object[] args) { if (((paramTypes == null) && (args != null)) || ((paramTypes != null) && (args == null)) || ((paramTypes != null) && (args != null) && (paramTypes.length != args.length))) { throw new IllegalArgumentException("Parameter types must match the arguments"); } if (paramTypes == null || paramTypes.length == 0) { return new InstantiateTransformer<>(); } return new InstantiateTransformer<>(paramTypes, args); }
Constructor for no arg instance.
/** * Constructor for no arg instance. */
private InstantiateTransformer() { super(); iParamTypes = null; iArgs = null; }
Constructor that performs no validation. Use instantiateTransformer if you want that.

Note: from 4.0, the input parameters will be cloned

Params:
  • paramTypes – the constructor parameter types
  • args – the constructor arguments
/** * Constructor that performs no validation. * Use <code>instantiateTransformer</code> if you want that. * <p> * Note: from 4.0, the input parameters will be cloned * * @param paramTypes the constructor parameter types * @param args the constructor arguments */
public InstantiateTransformer(final Class<?>[] paramTypes, final Object[] args) { super(); iParamTypes = paramTypes != null ? paramTypes.clone() : null; iArgs = args != null ? args.clone() : null; }
Transforms the input Class object to a result by instantiation.
Params:
  • input – the input object to transform
Returns:the transformed result
/** * Transforms the input Class object to a result by instantiation. * * @param input the input object to transform * @return the transformed result */
@Override public T transform(final Class<? extends T> input) { try { if (input == null) { throw new FunctorException( "InstantiateTransformer: Input object was not an instanceof Class, it was a null object"); } final Constructor<? extends T> con = input.getConstructor(iParamTypes); return con.newInstance(iArgs); } catch (final NoSuchMethodException ex) { throw new FunctorException("InstantiateTransformer: The constructor must exist and be public "); } catch (final InstantiationException ex) { throw new FunctorException("InstantiateTransformer: InstantiationException", ex); } catch (final IllegalAccessException ex) { throw new FunctorException("InstantiateTransformer: Constructor must be public", ex); } catch (final InvocationTargetException ex) { throw new FunctorException("InstantiateTransformer: Constructor threw an exception", ex); } } }