/*

 * Copyright 2005-2008 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.swing;

import java.security.*;

import java.lang.reflect.*;

/**

 * A utility for accessing and invoking methods, via reflection,

 * that would otherwise be unaccessible.

 *

 * @author Shannon Hickey

 */

public class AccessibleMethod {

    private final Method method;

    /**

     * Construct an instance for the given params.

     *

     * @param klass the class to which the method belongs

     * @param methodName the name of the method

     * @param paramTypes the paramater type array

     * @throws NullPointerException if <code>klass</code>

     *         or <code>name</code> is <code>null</code>

     * @throws NoSuchMethodException if the method can't be found

     */

    public AccessibleMethod(Class klass,

                            String methodName,

                            Class ... paramTypes) throws NoSuchMethodException {

        try {

            method = AccessController.doPrivileged(

                new AccessMethodAction(klass, methodName, paramTypes));

        } catch (PrivilegedActionException e) {

            throw (NoSuchMethodException)e.getCause();

        }

    }

    /**

     * Invoke the method that this object represents.

     * Has the same behavior and throws the same exceptions as

     * <code>java.lang.reflect.Method.invoke</code> with one

     * exception: This method does not throw

     * <code>IllegalAccessException</code> since the target

     * method has already been made accessible.

     *

     * @param obj the object the underlying method is invoked from

     * @param args the arguments used for the method call

     * @return the result of dispatching the method represented by

     *         this object on <code>obj</code> with parameters

     *         <code>args</code>

     * @see java.lang.reflect.Method#invoke

     */

    public Object invoke(Object obj, Object ... args)

            throws IllegalArgumentException, InvocationTargetException {

        try {

            return method.invoke(obj, args);

        } catch (IllegalAccessException e) {

            // should never happen since we've made it accessible

            throw new AssertionError("accessible method inaccessible");

        }

    }

    /**

     * Invoke the method that this object represents, with the

     * expectation that the method being called throws no

     * checked exceptions.

     * <p>

     * Simply calls <code>this.invoke(obj, args)</code>

     * but catches any <code>InvocationTargetException</code>

     * and returns the cause wrapped in a runtime exception.

     *

     * @param obj the object the underlying method is invoked from

     * @param args the arguments used for the method call

     * @return the result of dispatching the method represented by

     *         this object on <code>obj</code> with parameters

     *         <code>args</code>

     * @see #invoke

     */

    public Object invokeNoChecked(Object obj, Object ... args) {

        try {

            return invoke(obj, args);

        } catch (InvocationTargetException ex) {

            if (ex.getCause() instanceof RuntimeException) {

                throw (RuntimeException)ex.getCause();

            } else {

                throw new RuntimeException(ex.getCause());

            }

        }

    }

    /** The action used to fetch the method and make it accessible */

    private static class AccessMethodAction implements PrivilegedExceptionAction<Method> {

        private final Class<?> klass;

        private final String methodName;

        private final Class[] paramTypes;

        public AccessMethodAction(Class klass,

                                  String methodName,

                                  Class ... paramTypes) {

            this.klass = klass;

            this.methodName = methodName;

            this.paramTypes = paramTypes;

        }

        public Method run() throws NoSuchMethodException {

            Method method = klass.getDeclaredMethod(methodName, paramTypes);

            method.setAccessible(true);

            return method;

        }

    }

}