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;
18
19 import org.apache.commons.jexl3.JexlContext;
20 import org.apache.commons.jexl3.introspection.JexlUberspect;
21
22 import java.util.HashMap;
23 import java.util.LinkedHashSet;
24 import java.util.Map;
25 import java.util.Set;
26 import java.util.concurrent.locks.ReadWriteLock;
27 import java.util.concurrent.locks.ReentrantReadWriteLock;
28
29 /**
30 * Helper resolving a simple class name into a fully-qualified class name (hence FqcnResolver) using
31 * package names as roots of import.
32 * <p>This only keeps names of classes to avoid any class loading/reloading/permissions issue.</p>
33 */
34 class FqcnResolver implements JexlContext.ClassNameResolver {
35 /**
36 * The class loader.
37 */
38 private final JexlUberspect uberspect;
39 /**
40 * A lock for RW concurrent ops.
41 */
42 private final ReadWriteLock lock = new ReentrantReadWriteLock();
43 /**
44 * The set of packages to be used as import roots.
45 */
46 private final Set<String> imports = new LinkedHashSet<>();
47 /**
48 * The map of solved fqcns based on imports keyed on (simple) name,
49 * valued as fully-qualified class name.
50 */
51 private final Map<String, String> fqcns = new HashMap<>();
52 /**
53 * Optional parent solver.
54 */
55 private final FqcnResolver parent;
56
57 /**
58 * Adds a collection of packages as import root, checks the names are one of a package.
59 * @param names the package names
60 */
61 private void importCheck(final Iterable<String> names) {
62 if (names != null) {
63 names.forEach(this::importCheck);
64 }
65 }
66
67 /**
68 * Adds a package as import root, checks the name if one of a package.
69 * @param name the package name
70 */
71 private void importCheck(final String name) {
72 // check the package name actually points to a package to avoid clutter
73 if (name != null && Package.getPackage(name) != null) {
74 imports.add(name);
75 }
76 }
77
78 @Override
79 public String resolveClassName(final String name) {
80 return getQualifiedName(name);
81 }
82
83 /**
84 * Creates a class name solver.
85 *
86 * @param uber the optional class loader
87 * @param packages the optional package names
88 */
89 FqcnResolver(final JexlUberspect uber, final Iterable<String> packages) {
90 this.uberspect = uber;
91 this.parent = null;
92 importCheck(packages);
93 }
94
95 /**
96 * Creates a class name solver.
97 *
98 * @param solver the parent solver
99 * @throws NullPointerException if parent solver is null
100 */
101 FqcnResolver(final FqcnResolver solver) {
102 if (solver == null) {
103 throw new NullPointerException("parent solver can not be null");
104 }
105 this.parent = solver;
106 this.uberspect = solver.uberspect;
107 }
108
109 /**
110 * Checks is a package is imported by this solver of one of its ascendants.
111 *
112 * @param pkg the package name
113 * @return true if an import exists for this package, false otherwise
114 */
115 boolean isImporting(final String pkg) {
116 if (parent != null && parent.isImporting(pkg)) {
117 return true;
118 }
119 lock.readLock().lock();
120 try {
121 return imports.contains(pkg);
122 } finally {
123 lock.readLock().unlock();
124 }
125 }
126
127 /**
128 * Imports a list of packages as solving roots.
129 *
130 * @param packages the packages
131 * @return this solver
132 */
133 FqcnResolver importPackages(final Iterable<String> packages) {
134 if (packages != null) {
135 lock.writeLock().lock();
136 try {
137 if (parent == null) {
138 importCheck(packages);
139 } else {
140 packages.forEach(pkg ->{ if (!parent.isImporting(pkg)) { importCheck(pkg); }});
141 }
142 } finally {
143 lock.writeLock().unlock();
144 }
145 }
146 return this;
147 }
148
149 /**
150 * Gets a fully qualified class name from a simple class name and imports.
151 *
152 * @param name the simple name
153 * @return the fqcn
154 */
155 String getQualifiedName(final String name) {
156 String fqcn;
157 if (parent != null && (fqcn = parent.getQualifiedName(name)) != null) {
158 return fqcn;
159 }
160 lock.readLock().lock();
161 try {
162 fqcn = fqcns.get(name);
163 } finally {
164 lock.readLock().unlock();
165 }
166 if (fqcn == null) {
167 final ClassLoader loader = uberspect.getClassLoader();
168 for (final String pkg : imports) {
169 Class<?> clazz;
170 try {
171 clazz = loader.loadClass(pkg + "." + name);
172 } catch (final ClassNotFoundException e) {
173 // not in this package
174 continue;
175 }
176 // solved it, insert in map and return
177 if (clazz != null) {
178 fqcn = clazz.getName();
179 lock.writeLock().lock();
180 try {
181 fqcns.put(name, fqcn);
182 } finally {
183 lock.writeLock().unlock();
184 }
185 break;
186 }
187 }
188 }
189 return fqcn;
190 }
191 }