org.apache.commons.collections4.functors.InstantiateTransformer Maven / Gradle / Ivy
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/*
* 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
* limitations under the License.
*/
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
*/
public class InstantiateTransformer implements Transformer, T> {
/** Singleton instance that uses the no arg constructor */
@SuppressWarnings("rawtypes")
private static final Transformer NO_ARG_INSTANCE = new InstantiateTransformer<>();
/** The constructor parameter types */
private final Class[] iParamTypes;
/** The constructor arguments */
private final Object[] iArgs;
/**
* Get a typed no-arg instance.
*
* @param the type of the objects to be created
* @return Transformer<Class<? extends T>, T>
*/
public static Transformer, T> instantiateTransformer() {
return NO_ARG_INSTANCE;
}
/**
* Transformer method that performs validation.
*
* @param 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 Transformer, 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.
*/
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
*
* @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.
*
* @param input the input object to transform
* @return the transformed result
*/
@Override
public T transform(final Class input) {
try {
if (input == null) {
throw new FunctorException(
"InstantiateTransformer: Input object was not an instanceof Class, it was a null object");
}
final Constructor 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);
}
}
}