1 /*

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

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

     4  *

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

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

     7  * published by the Free Software Foundation.  Sun designates this

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

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

    10  *

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

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

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

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

    15  * accompanied this code).

    16  *

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

    18  * 2 along with this work; if not, write to the Free Software Foundation,

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

    20  *

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

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

    23  * have any questions.

    24  */

    25 package sun.swing;

    26 

    27 import java.security.*;

    28 import java.lang.reflect.*;

    29 

    30 /**

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

    32  * that would otherwise be unaccessible.

    33  *

    34  * @author Shannon Hickey

    35  */

    36 public class AccessibleMethod {

    37 

    38     private final Method method;

    39 

    40     /**

    41      * Construct an instance for the given params.

    42      *

    43      * @param klass the class to which the method belongs

    44      * @param methodName the name of the method

    45      * @param paramTypes the paramater type array

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

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

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

    49      */

    50     public AccessibleMethod(Class klass,

    51                             String methodName,

    52                             Class ... paramTypes) throws NoSuchMethodException {

    53         try {

    54             method = AccessController.doPrivileged(

    55                 new AccessMethodAction(klass, methodName, paramTypes));

    56         } catch (PrivilegedActionException e) {

    57             throw (NoSuchMethodException)e.getCause();

    58         }

    59     }

    60 

    61     /**

    62      * Invoke the method that this object represents.

    63      * Has the same behavior and throws the same exceptions as

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

    65      * exception: This method does not throw

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

    67      * method has already been made accessible.

    68      *

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

    70      * @param args the arguments used for the method call

    71      * @return the result of dispatching the method represented by

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

    73      *         <code>args</code>

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

    75      */

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

    77             throws IllegalArgumentException, InvocationTargetException {

    78 

    79         try {

    80             return method.invoke(obj, args);

    81         } catch (IllegalAccessException e) {

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

    83             throw new AssertionError("accessible method inaccessible");

    84         }

    85     }

    86 

    87     /**

    88      * Invoke the method that this object represents, with the

    89      * expectation that the method being called throws no

    90      * checked exceptions.

    91      * <p>

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

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

    94      * and returns the cause wrapped in a runtime exception.

    95      *

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

    97      * @param args the arguments used for the method call

    98      * @return the result of dispatching the method represented by

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

   100      *         <code>args</code>

   101      * @see #invoke

   102      */

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

   104         try {

   105             return invoke(obj, args);

   106         } catch (InvocationTargetException ex) {

   107             if (ex.getCause() instanceof RuntimeException) {

   108                 throw (RuntimeException)ex.getCause();

   109             } else {

   110                 throw new RuntimeException(ex.getCause());

   111             }

   112         }

   113     }

   114 

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

   116     private static class AccessMethodAction implements PrivilegedExceptionAction<Method> {

   117         private final Class<?> klass;

   118         private final String methodName;

   119         private final Class[] paramTypes;

   120 

   121         public AccessMethodAction(Class klass,

   122                                   String methodName,

   123                                   Class ... paramTypes) {

   124 

   125             this.klass = klass;

   126             this.methodName = methodName;

   127             this.paramTypes = paramTypes;

   128         }

   129 

   130         public Method run() throws NoSuchMethodException {

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

   132             method.setAccessible(true);

   133             return method;

   134         }

   135     }

   136 }