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 }