1 /*
   2  * Copyright (c) 2017, 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 java.lang;
  27 
  28 import java.lang.invoke.*;
  29 import java.lang.invoke.MethodHandles.Lookup;
  30 import java.lang.reflect.InvocationTargetException;
  31 
  32 import static java.lang.invoke.MethodType.*;
  33 
  34 /*
  35  * Verify that a Lookup object can be obtained statically from java.base
  36  * but fails when it's obtained via reflection from java.base.
  37  */
  38 public class LookupTest {
  39     public static void main(String... args) throws Throwable {
  40         // Get a full power lookup
  41         Lookup lookup1 =  MethodHandles.lookup();
  42         MethodHandle mh1 = lookup1.findStatic(lookup1.lookupClass(),
  43                                               "foo",
  44                                               methodType(String.class));
  45         assertEquals((String) mh1.invokeExact(), foo());
  46 
  47         // access protected member
  48         MethodHandle mh2 = lookup1.findVirtual(java.lang.ClassLoader.class,
  49                                                "getPackage",
  50                                                methodType(Package.class, String.class));
  51         ClassLoader loader = ClassLoader.getPlatformClassLoader();
  52         Package pkg = (Package)mh2.invokeExact(loader, "java.lang");
  53         assertEquals(pkg.getName(), "java.lang");
  54 
  55         // MethodHandles.lookup will fail if it's called reflectively
  56         try {
  57             MethodHandles.class.getMethod("lookup").invoke(null);
  58         } catch (InvocationTargetException e) {
  59             if (!(e.getCause() instanceof IllegalArgumentException)) {
  60                 throw e.getCause();
  61             }
  62         }
  63     }
  64 
  65     static String foo() { return "foo!"; }
  66 
  67     static void assertEquals(Object o1, Object o2) {
  68         if (!o1.equals(o2)) {
  69             throw new RuntimeException(o1 + " != " + o2);
  70         }
  71     }
  72 }