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    1   /*
    2    * Copyright (c) 2005, 2011, Oracle and/or its affiliates. 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.  Oracle designates this
    8    * particular file as subject to the "Classpath" exception as provided
    9    * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   22    * or visit www.oracle.com if you need additional information or have any
   23    * questions.
   24    */
   25   
   26   package com.sun.script.util;
   27   
   28   import javax.script;
   29   import java.lang.reflect;
   30   import java.security;
   31   
   32   /*
   33    * java.lang.reflect.Proxy based interface implementor. This is meant
   34    * to be used to implement Invocable.getInterface.
   35    *
   36    * @author Mike Grogan
   37    * @since 1.6
   38    */
   39   public class InterfaceImplementor {
   40   
   41       private Invocable engine;
   42   
   43       /** Creates a new instance of Invocable */
   44       public InterfaceImplementor(Invocable engine) {
   45           this.engine = engine;
   46       }
   47   
   48       private final class InterfaceImplementorInvocationHandler
   49                           implements InvocationHandler {
   50           private Object thiz;
   51           private AccessControlContext accCtxt;
   52   
   53           public InterfaceImplementorInvocationHandler(Object thiz,
   54               AccessControlContext accCtxt) {
   55               this.thiz = thiz;
   56               this.accCtxt = accCtxt;
   57           }
   58   
   59           public Object invoke(Object proxy , Method method, Object[] args)
   60           throws java.lang.Throwable {
   61               // give chance to convert input args
   62               args = convertArguments(method, args);
   63               Object result;
   64               final Method m = method;
   65               final Object[] a = args;
   66               result = AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
   67                   public Object run() throws Exception {
   68                       if (thiz == null) {
   69                           return engine.invokeFunction(m.getName(), a);
   70                       } else {
   71                           return engine.invokeMethod(thiz, m.getName(), a);
   72                       }
   73                   }
   74               }, accCtxt);
   75               // give chance to convert the method result
   76               return convertResult(method, result);
   77           }
   78       }
   79   
   80       public <T> T getInterface(Object thiz, Class<T> iface)
   81       throws ScriptException {
   82           if (iface == null || !iface.isInterface()) {
   83               throw new IllegalArgumentException("interface Class expected");
   84           }
   85           if (! isImplemented(thiz, iface)) {
   86               return null;
   87           }
   88           AccessControlContext accCtxt = AccessController.getContext();
   89           return iface.cast(Proxy.newProxyInstance(iface.getClassLoader(),
   90               new Class[]{iface},
   91               new InterfaceImplementorInvocationHandler(thiz, accCtxt)));
   92       }
   93   
   94       protected boolean isImplemented(Object thiz, Class<?> iface) {
   95           return true;
   96       }
   97   
   98       // called to convert method result after invoke
   99       protected Object convertResult(Method method, Object res)
  100                                      throws ScriptException {
  101           // default is identity conversion
  102           return res;
  103       }
  104   
  105       // called to convert method arguments before invoke
  106       protected Object[] convertArguments(Method method, Object[] args)
  107                                         throws ScriptException {
  108           // default is identity conversion
  109           return args;
  110       }
  111   }

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