- /*
- * 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.InvocationTargetException;
- import java.lang.reflect.Method;
-
- 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: 1.7 $ $Date: 2004/05/26 21:44:05 $
- *
- * @author Stephen Colebourne
- */
- public class InvokerTransformer implements Transformer, Serializable {
-
- /** The serial version */
- static final long serialVersionUID = -8653385846894047688L;
-
- /** The method name to call */
- private final String iMethodName;
- /** The array of reflection parameter types */
- private final Class[] iParamTypes;
- /** The array of reflection arguments */
- private final Object[] iArgs;
-
- /**
- * Gets an instance of this transformer calling a specific method with no arguments.
- *
- * @param methodName the method name to call
- * @return an invoker transformer
- * @since Commons Collections 3.1
- */
- public static Transformer getInstance(String methodName) {
- if (methodName == null) {
- throw new IllegalArgumentException("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.
- *
- * @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
- */
- public static Transformer getInstance(String methodName, Class[] paramTypes, Object[] args) {
- if (methodName == null) {
- throw new IllegalArgumentException("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);
- } else {
- paramTypes = (Class[]) paramTypes.clone();
- args = (Object[]) args.clone();
- return new InvokerTransformer(methodName, paramTypes, args);
- }
- }
-
- /**
- * Constructor for no arg instance.
- *
- * @param methodName the method to call
- */
- private InvokerTransformer(String methodName) {
- super();
- iMethodName = methodName;
- iParamTypes = null;
- iArgs = null;
- }
-
- /**
- * Constructor that performs no validation.
- * Use <code>getInstance</code> if you want that.
- *
- * @param methodName the method to call
- * @param paramTypes the constructor parameter types, not cloned
- * @param args the constructor arguments, not cloned
- */
- public InvokerTransformer(String methodName, Class[] paramTypes, Object[] args) {
- super();
- iMethodName = methodName;
- iParamTypes = paramTypes;
- iArgs = args;
- }
-
- /**
- * 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
- */
- public Object transform(Object input) {
- if (input == null) {
- return null;
- }
- try {
- Class cls = input.getClass();
- Method method = cls.getMethod(iMethodName, iParamTypes);
- return method.invoke(input, iArgs);
-
- } catch (NoSuchMethodException ex) {
- throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" + input.getClass() + "' does not exist");
- } catch (IllegalAccessException ex) {
- throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" + input.getClass() + "' cannot be accessed");
- } catch (InvocationTargetException ex) {
- throw new FunctorException("InvokerTransformer: The method '" + iMethodName + "' on '" + input.getClass() + "' threw an exception", ex);
- }
- }
-
- }