1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.jexl3.internal.introspection;
18
19 import java.lang.invoke.MethodHandle;
20 import java.lang.invoke.MethodHandles;
21 import java.lang.invoke.MethodType;
22
23 /**
24 * Utility for Java9+ backport in Java8 of class and module related methods.
25 */
26 class ClassTool {
27 /** The Class.getModule() method. */
28 private static final MethodHandle GET_MODULE;
29 /** The Class.getPackageName() method. */
30 private static final MethodHandle GET_PKGNAME;
31 /** The Module.isExported(String packageName) method. */
32 private static final MethodHandle IS_EXPORTED;
33
34 static {
35 final MethodHandles.Lookup LOOKUP = MethodHandles.lookup();
36 MethodHandle getModule = null;
37 MethodHandle getPackageName = null;
38 MethodHandle isExported = null;
39 try {
40 final Class<?> modulec = ClassTool.class.getClassLoader().loadClass("java.lang.Module");
41 if (modulec != null) {
42 getModule = LOOKUP.findVirtual(Class.class, "getModule", MethodType.methodType(modulec));
43 if (getModule != null) {
44 getPackageName = LOOKUP.findVirtual(Class.class, "getPackageName", MethodType.methodType(String.class));
45 if (getPackageName != null) {
46 isExported = LOOKUP.findVirtual(modulec, "isExported", MethodType.methodType(boolean.class, String.class));
47 }
48 }
49 }
50 } catch (final Exception e) {
51 // ignore all
52 }
53 GET_MODULE = getModule;
54 GET_PKGNAME = getPackageName;
55 IS_EXPORTED = isExported;
56 }
57
58 /**
59 * Checks whether a class is exported by its module (java 9+).
60 * The code performs the following sequence through reflection (since the same jar can run
61 * on a Java8 or Java9+ runtime and the module features does not exist on 8).
62 * <code>
63 * Module module = declarator.getModule();
64 * return module.isExported(declarator.getPackageName());
65 * </code>
66 * This is required since some classes and methods may not be exported thus not callable through
67 * reflection.
68 *
69 * @param declarator the class
70 * @return true if class is exported or no module support exists
71 */
72 static boolean isExported(final Class<?> declarator) {
73 if (IS_EXPORTED != null) {
74 try {
75 final Object module = GET_MODULE.invoke(declarator);
76 if (module != null) {
77 final String pkgName = (String) GET_PKGNAME.invoke(declarator);
78 return (Boolean) IS_EXPORTED.invoke(module, pkgName);
79 }
80 } catch (final Throwable e) {
81 // ignore
82 }
83 }
84 return true;
85 }
86
87 /**
88 * Gets the package name of a class (class.getPackage() may return null).
89 *
90 * @param clz the class
91 * @return the class package name
92 */
93 static String getPackageName(final Class<?> clz) {
94 String pkgName = "";
95 if (clz != null) {
96 // use native if we can
97 if (GET_PKGNAME != null) {
98 try {
99 return (String) GET_PKGNAME.invoke(clz);
100 } catch (final Throwable xany) {
101 return "";
102 }
103 }
104 // remove array
105 Class<?> clazz = clz;
106 while (clazz.isArray()) {
107 clazz = clazz.getComponentType();
108 }
109 // mimic getPackageName()
110 if (clazz.isPrimitive()) {
111 return "java.lang";
112 }
113 // remove enclosing
114 Class<?> walk = clazz.getEnclosingClass();
115 while (walk != null) {
116 clazz = walk;
117 walk = walk.getEnclosingClass();
118 }
119 final Package pkg = clazz.getPackage();
120 // pkg may be null for unobvious reasons
121 if (pkg == null) {
122 final String name = clazz.getName();
123 final int dot = name.lastIndexOf('.');
124 if (dot > 0) {
125 pkgName = name.substring(0, dot);
126 }
127 } else {
128 pkgName = pkg.getName();
129 }
130 }
131 return pkgName;
132 }
133
134 }