- /*
- * Copyright 2001-2004 The Apache Software Foundation
- *
- * Licensed 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.collections.functors;
-
- import java.io.Serializable;
- import java.lang.reflect.Constructor;
- import java.lang.reflect.InvocationTargetException;
-
- import org.apache.commons.collections.FunctorException;
- import org.apache.commons.collections.Transformer;
-
- /**
- * Transformer implementation that creates a new object instance by reflection.
- *
- * @since Commons Collections 3.0
- * @version $Revision: 1.6 $ $Date: 2004/05/16 11:36:31 $
- *
- * @author Stephen Colebourne
- */
- public class InstantiateTransformer implements Transformer, Serializable {
-
- /** The serial version */
- static final long serialVersionUID = 3786388740793356347L;
-
- /** Singleton instance that uses the no arg constructor */
- public static final Transformer NO_ARG_INSTANCE = new InstantiateTransformer();
-
- /** The constructor parameter types */
- private final Class[] iParamTypes;
- /** The constructor arguments */
- private final Object[] iArgs;
-
- /**
- * Transformer method that performs validation.
- *
- * @param paramTypes the constructor parameter types
- * @param args the constructor arguments
- * @return an instantiate transformer
- */
- public static Transformer getInstance(Class[] paramTypes, 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 NO_ARG_INSTANCE;
- } else {
- paramTypes = (Class[]) paramTypes.clone();
- args = (Object[]) args.clone();
- }
- return new InstantiateTransformer(paramTypes, args);
- }
-
- /**
- * Constructor for no arg instance.
- */
- private InstantiateTransformer() {
- super();
- iParamTypes = null;
- iArgs = null;
- }
-
- /**
- * Constructor that performs no validation.
- * Use <code>getInstance</code> if you want that.
- *
- * @param paramTypes the constructor parameter types, not cloned
- * @param args the constructor arguments, not cloned
- */
- public InstantiateTransformer(Class[] paramTypes, Object[] args) {
- super();
- iParamTypes = paramTypes;
- iArgs = args;
- }
-
- /**
- * Transforms the input Class object to a result by instantiation.
- *
- * @param input the input object to transform
- * @return the transformed result
- */
- public Object transform(Object input) {
- try {
- if (input instanceof Class == false) {
- throw new FunctorException(
- "InstantiateTransformer: Input object was not an instanceof Class, it was a "
- + (input == null ? "null object" : input.getClass().getName()));
- }
- Constructor con = ((Class) input).getConstructor(iParamTypes);
- return con.newInstance(iArgs);
-
- } catch (NoSuchMethodException ex) {
- throw new FunctorException("InstantiateTransformer: The constructor must exist and be public ");
- } catch (InstantiationException ex) {
- throw new FunctorException("InstantiateTransformer: InstantiationException", ex);
- } catch (IllegalAccessException ex) {
- throw new FunctorException("InstantiateTransformer: Constructor must be public", ex);
- } catch (InvocationTargetException ex) {
- throw new FunctorException("InstantiateTransformer: Constructor threw an exception", ex);
- }
- }
-
- }