/*
 * 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.InvocationTargetException;
import java.lang.reflect.Method;

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 InvokerTransformer<I, O> implements Transformer<I, O> {
The method name to call
/** The method name to call */
private final String iMethodName;
The array of reflection parameter types
/** The array of reflection parameter types */
private final Class<?>[] iParamTypes;
The array of reflection arguments
/** The array of reflection arguments */
private final Object[] iArgs;
Gets an instance of this transformer calling a specific method with no arguments.
Params:
  • methodName – the method name to call
Type parameters:
  • <I> – the input type
  • <O> – the output type
Throws:
Returns:an invoker transformer
Since:3.1
/** * Gets an instance of this transformer calling a specific method with no arguments. * * @param <I> the input type * @param <O> the output type * @param methodName the method name to call * @return an invoker transformer * @throws NullPointerException if methodName is null * @since 3.1 */
public static <I, O> Transformer<I, O> invokerTransformer(final String methodName) { if (methodName == null) { throw new NullPointerException("The method to invoke must not be null"); } return new InvokerTransformer<>(methodName); }
Gets an instance of this transformer calling a specific method with specific values.
Params:
  • methodName – the method name to call
  • paramTypes – the parameter types of the method
  • args – the arguments to pass to the method
Type parameters:
  • <I> – the input type
  • <O> – the output type
Throws:
Returns:an invoker transformer
/** * Gets an instance of this transformer calling a specific method with specific values. * * @param <I> the input type * @param <O> the output type * @param methodName the method name to call * @param paramTypes the parameter types of the method * @param args the arguments to pass to the method * @return an invoker transformer * @throws NullPointerException if methodName is null * @throws IllegalArgumentException if paramTypes does not match args */
public static <I, O> Transformer<I, O> invokerTransformer(final String methodName, final Class<?>[] paramTypes, final Object[] args) { if (methodName == null) { throw new NullPointerException("The method to invoke must not be null"); } if (((paramTypes == null) && (args != null)) || ((paramTypes != null) && (args == null)) || ((paramTypes != null) && (args != null) && (paramTypes.length != args.length))) { throw new IllegalArgumentException("The parameter types must match the arguments"); } if (paramTypes == null || paramTypes.length == 0) { return new InvokerTransformer<>(methodName); } return new InvokerTransformer<>(methodName, paramTypes, args); }
Constructor for no arg instance.
Params:
  • methodName – the method to call
/** * Constructor for no arg instance. * * @param methodName the method to call */
private InvokerTransformer(final String methodName) { super(); iMethodName = methodName; iParamTypes = null; iArgs = null; }
Constructor that performs no validation. Use invokerTransformer if you want that.

Note: from 4.0, the input parameters will be cloned

Params:
  • methodName – the method to call
  • paramTypes – the constructor parameter types
  • args – the constructor arguments
/** * Constructor that performs no validation. * Use <code>invokerTransformer</code> if you want that. * <p> * Note: from 4.0, the input parameters will be cloned * * @param methodName the method to call * @param paramTypes the constructor parameter types * @param args the constructor arguments */
public InvokerTransformer(final String methodName, final Class<?>[] paramTypes, final Object[] args) { super(); iMethodName = methodName; iParamTypes = paramTypes != null ? paramTypes.clone() : null; iArgs = args != null ? args.clone() : null; }
Transforms the input to result by invoking a method on the input.
Params:
  • input – the input object to transform
Returns:the transformed result, null if null input
/** * Transforms the input to result by invoking a method on the input. * * @param input the input object to transform * @return the transformed result, null if null input */
@Override @SuppressWarnings("unchecked") public O transform(final Object input) { if (input == null) { return null; } try { final Class<?> cls = input.getClass(); final Method method = cls.getMethod(iMethodName, iParamTypes); return (O) method.invoke(input, iArgs); } catch (final NoSuchMethodException ex) { throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" + input.getClass() + "' does not exist"); } catch (final IllegalAccessException ex) { throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" + input.getClass() + "' cannot be accessed"); } catch (final InvocationTargetException ex) { throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" + input.getClass() + "' threw an exception", ex); } } }