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    1   /*
    2    * Copyright 2005-2006 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   }

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