1 /*
2 * Copyright 2013 the original author or authors.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package org.callbackparams.support;
17
18 import java.util.regex.Pattern;
19
20 /**
21 * Provides utility methods to help out wherever the framework shall
22 * act in different ways on different JDK versions.
23 * The only thing that is checked on the JDK version is whether it supports
24 * Java5-or-later (i.e. are annotations supported) or if only Java 1.4.x
25 * is supported.
26 *
27 * @author Henrik Kaipe
28 */
29 public class JdkVersion {
30
31 private static final boolean annotationsAreSupported = new Object() {
32 public int hashCode() {
33 try {
34 Class.forName("java.lang.annotation.Annotation");
35 return 5;
36 } catch (Exception detection_of_JDK_version_1_4_or_earlier) {
37 return 4;
38 }
39 }
40 }.hashCode() >= 5;
41 private static final Pattern packageName = annotationsAreSupported
42 ? Pattern.compile("^.*\\.") : null;
43
44 /**
45 * @return true on Java-5 or later; false on Java 1.4.x
46 */
47 public static boolean supportsAnnotations() {
48 return annotationsAreSupported;
49 }
50
51 /**
52 * On Java-5 or later the method tries to wrap a class with the same
53 * name as the argument class but from the "annotation" sub-package.
54 * On Java 1.4.x the method will simply wrap the argument class.
55 *
56 * @param c a class that is byte-code compatible with Java 1.4.x
57 */
58 public static ClassWrapper compatibleImplementationOf(Class c) {
59 if (supportsAnnotations()) {
60 try {
61 c = Class.forName(packageName
62 .matcher(c.getName()).replaceFirst("$0annotation."));
63 } catch (ClassNotFoundException ex) {
64 throw ExceptionUtil.unchecked(ex);
65 }
66 }
67 return new ClassWrapper(c);
68 }
69 }