1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.commons.compress.compressors.brotli;
20
21 import org.apache.commons.compress.utils.OsgiUtils;
22
23 /**
24 * Utility code for the Brotli compression format.
25 *
26 * @ThreadSafe
27 * @since 1.14
28 */
29 public class BrotliUtils {
30
31 enum CachedAvailability {
32 DONT_CACHE, CACHED_AVAILABLE, CACHED_UNAVAILABLE
33 }
34
35 private static volatile CachedAvailability cachedBrotliAvailability;
36
37 static {
38 cachedBrotliAvailability = CachedAvailability.DONT_CACHE;
39 setCacheBrotliAvailablity(!OsgiUtils.isRunningInOsgiEnvironment());
40 }
41
42 // only exists to support unit tests
43 static CachedAvailability getCachedBrotliAvailability() {
44 return cachedBrotliAvailability;
45 }
46
47 private static boolean internalIsBrotliCompressionAvailable() {
48 try {
49 Class.forName("org.brotli.dec.BrotliInputStream");
50 return true;
51 } catch (final NoClassDefFoundError | Exception error) { // NOSONAR
52 return false;
53 }
54 }
55
56 /**
57 * Are the classes required to support Brotli compression available?
58 *
59 * @return true if the classes required to support Brotli compression are available
60 */
61 public static boolean isBrotliCompressionAvailable() {
62 final CachedAvailability cachedResult = cachedBrotliAvailability;
63 if (cachedResult != CachedAvailability.DONT_CACHE) {
64 return cachedResult == CachedAvailability.CACHED_AVAILABLE;
65 }
66 return internalIsBrotliCompressionAvailable();
67 }
68
69 /**
70 * Whether to cache the result of the Brotli for Java check.
71 *
72 * <p>
73 * This defaults to {@code false} in an OSGi environment and {@code true} otherwise.
74 * </p>
75 *
76 * @param doCache whether to cache the result
77 */
78 public static void setCacheBrotliAvailablity(final boolean doCache) {
79 if (!doCache) {
80 cachedBrotliAvailability = CachedAvailability.DONT_CACHE;
81 } else if (cachedBrotliAvailability == CachedAvailability.DONT_CACHE) {
82 final boolean hasBrotli = internalIsBrotliCompressionAvailable();
83 cachedBrotliAvailability = hasBrotli ? CachedAvailability.CACHED_AVAILABLE : CachedAvailability.CACHED_UNAVAILABLE;
84 }
85 }
86
87 /** Private constructor to prevent instantiation of this utility class. */
88 private BrotliUtils() {
89 }
90 }