methodutils.java

osworkflow修改版本

/*
 * $Header: /cvs/osworkflow/src/designer/com/opensymphony/workflow/designer/beanutils/MethodUtils.java,v 1.2 2004/04/16 10:36:29 hani Exp $
 * $Revision: 1.2 $
 * $Date: 2004/04/16 10:36:29 $
 *
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001-2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. The names "Apache", "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache" nor may "Apache" appear in their names without prior
 *    written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package com.opensymphony.workflow.designer.beanutils;


import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

import java.util.WeakHashMap;

/**
 * <p> Utility reflection methods focussed on methods in general rather than properties in particular. </p>
 *
 * <h3>Known Limitations</h3>
 * <h4>Accessing Public Methods In A Default Access Superclass</h4>
 * <p>There is an issue when invoking public methods contained in a default access superclass.
 * Reflection locates these methods fine and correctly assigns them as public.
 * However, an <code>IllegalAccessException</code> is thrown if the method is invoked.</p>
 *
 * <p><code>MethodUtils</code> contains a workaround for this situation.
 * It will attempt to call <code>setAccessible</code> on this method.
 * If this call succeeds, then the method can be invoked as normal.
 * This call will only succeed when the application has sufficient security privilages.
 * If this call fails then a warning will be logged and the method may fail.</p>
 *
 * @author Craig R. McClanahan
 * @author Ralph Schaer
 * @author Chris Audley
 * @author Rey Fran鏾is
 * @author Gregor Ra齧an
 * @author Jan Sorensen
 * @author Robert Burrell Donkin
 */

public class MethodUtils {

    // --------------------------------------------------------- Private Methods

    /** Only log warning about accessibility work around once */
    private static boolean loggedAccessibleWarning = false;

    /** An empty class array */
    private static final Class[] emptyClassArray = new Class[0];
    /** An empty object array */
    private static final Object[] emptyObjectArray = new Object[0];

    /**
     * Stores a cache of Methods against MethodDescriptors, in a WeakHashMap.
     */
    private static WeakHashMap cache = new WeakHashMap();

    // --------------------------------------------------------- Public Methods

    /**
     * <p>Invoke a named method whose parameter type matches the object type.</p>
     *
     * <p>The behaviour of this method is less deterministic
     * than {@link #invokeExactMethod}.
     * It loops through all methods with names that match
     * and then executes the first it finds with compatable parameters.</p>
     *
     * <p>This method supports calls to methods taking primitive parameters
     * via passing in wrapping classes. So, for example, a <code>Boolean</code> class
     * would match a <code>boolean</code> primitive.</p>
     *
     * <p> This is a convenient wrapper for
     * {@link #invokeMethod(Object object,String methodName,Object [] args)}.
     * </p>
     *
     * @param object invoke method on this object
     * @param methodName get method with this name
     * @param arg use this argument
     *
     * @throws NoSuchMethodException if there is no such accessible method
     * @throws InvocationTargetException wraps an exception thrown by the
     *  method invoked
     * @throws IllegalAccessException if the requested method is not accessible
     *  via reflection
     */
    public static Object invokeMethod(
            Object object,
            String methodName,
            Object arg)
            throws
            NoSuchMethodException,
            IllegalAccessException,
            InvocationTargetException {

        Object[] args = {arg};
        return invokeMethod(object, methodName, args);

    }


    /**
     * <p>Invoke a named method whose parameter type matches the object type.</p>
     *
     * <p>The behaviour of this method is less deterministic
     * than {@link #invokeExactMethod(Object object,String methodName,Object [] args)}.
     * It loops through all methods with names that match
     * and then executes the first it finds with compatable parameters.</p>
     *
     * <p>This method supports calls to methods taking primitive parameters
     * via passing in wrapping classes. So, for example, a <code>Boolean</code> class
     * would match a <code>boolean</code> primitive.</p>
     *
     * <p> This is a convenient wrapper for
     * {@link #invokeMethod(Object, String, Object[], Class[])} } }.
     * </p>
     *
     * @param object invoke method on this object
     * @param methodName get method with this name
     * @param args use these arguments - treat null as empty array
     *
     * @throws NoSuchMethodException if there is no such accessible method
     * @throws InvocationTargetException wraps an exception thrown by the
     *  method invoked
     * @throws IllegalAccessException if the requested method is not accessible
     *  via reflection
     */
    public static Object invokeMethod(
            Object object,
            String methodName,
            Object[] args)
            throws
            NoSuchMethodException,
            IllegalAccessException,
            InvocationTargetException {

        if (args == null) {
            args = emptyObjectArray;
        }
        int arguments = args.length;
        Class parameterTypes [] = new Class[arguments];
        for (int i = 0; i < arguments; i++) {
            parameterTypes[i] = args[i].getClass();
        }
        return invokeMethod(object, methodName, args, parameterTypes);

    }


    /**
     * <p>Invoke a named method whose parameter type matches the object type.</p>
     *
     * <p>The behaviour of this method is less deterministic
     * than {@link
     * #invokeExactMethod(Object object,String methodName,Object [] args,Class[] parameterTypes)}.
     * It loops through all methods with names that match
     * and then executes the first it finds with compatable parameters.</p>
     *
     * <p>This method supports calls to methods taking primitive parameters
     * via passing in wrapping classes. So, for example, a <code>Boolean</code> class
     * would match a <code>boolean</code> primitive.</p>
     *
     *
     * @param object invoke method on this object
     * @param methodName get method with this name
     * @param args use these arguments - treat null as empty array
     * @param parameterTypes match these parameters - treat null as empty array
     *
     * @throws NoSuchMethodException if there is no such accessible method
     * @throws InvocationTargetException wraps an exception thrown by the
     *  method invoked
     * @throws IllegalAccessException if the requested method is not accessible
     *  via reflection
     */
    public static Object invokeMethod(
            Object object,
            String methodName,
            Object[] args,
            Class[] parameterTypes)
                throws
                    NoSuchMethodException,
                    IllegalAccessException,
                    InvocationTargetException {

        if (parameterTypes == null) {
            parameterTypes = emptyClassArray;
        }
        if (args == null) {
            args = emptyObjectArray;
        }

        Method method = getMatchingAccessibleMethod(
                object.getClass(),
                methodName,
                parameterTypes);
        if (method == null)
            throw new NoSuchMethodException("No such accessible method: " +
                    methodName + "() on object: " + object.getClass().getName());
        return method.invoke(object, args);
    }


    /**
     * <p>Invoke a method whose parameter type matches exactly the object
     * type.</p>
     *
     * <p> This is a convenient wrapper for
     * {@link #invokeExactMethod(Object object,String methodName,Object [] args)}.
     * </p>
     *
     * @param object invoke method on this object
     * @param methodName get method with this name
     * @param arg use this argument
     *
     * @throws NoSuchMethodException if there is no such accessible method
     * @throws InvocationTargetException wraps an exception thrown by the
     *  method invoked
     * @throws IllegalAccessException if the requested method is not accessible
     *  via reflection
     */
    public static Object invokeExactMethod(
            Object object,
            String methodName,
            Object arg)
            throws
            NoSuchMethodException,
            IllegalAccessException,
            InvocationTargetException {