Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
GzipUtil |
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| 6.333333333333333;6.333 |
1 | // Copyright 2004, 2005 The Apache Software Foundation | |
2 | // | |
3 | // Licensed under the Apache License, Version 2.0 (the "License"); | |
4 | // you may not use this file except in compliance with the License. | |
5 | // You may obtain a copy of the License at | |
6 | // | |
7 | // http://www.apache.org/licenses/LICENSE-2.0 | |
8 | // | |
9 | // Unless required by applicable law or agreed to in writing, software | |
10 | // distributed under the License is distributed on an "AS IS" BASIS, | |
11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
12 | // See the License for the specific language governing permissions and | |
13 | // limitations under the License. | |
14 | package org.apache.tapestry.util.io; | |
15 | ||
16 | import org.apache.tapestry.web.WebRequest; | |
17 | ||
18 | ||
19 | /** | |
20 | * Encapsulates logic related to various gzip compression schemes and their rules | |
21 | * as they apply to different browsers. | |
22 | */ | |
23 | public final class GzipUtil | |
24 | { | |
25 | private static final float MIN_IE_VERSION = 7.0f; | |
26 | ||
27 | private static final String MSIE_6_COMPATIBLE_STRING = "SV1"; | |
28 | ||
29 | /* defeat instantiation */ | |
30 | 0 | private GzipUtil() { } |
31 | ||
32 | /** | |
33 | * Determines if gzip compression is appropriate/possible based on the User Agent and | |
34 | * other limiting factors. IE versions < 6.1 are known to not work with gzip compression reliably. | |
35 | * | |
36 | * @param request The current web request to check the headers of. | |
37 | * | |
38 | * @return True, if this request can be served in gzip format. False otherwise. | |
39 | */ | |
40 | public static boolean isGzipCapable(WebRequest request) | |
41 | { | |
42 | 0 | String encoding = request.getHeader("Accept-Encoding"); |
43 | ||
44 | 0 | if (encoding == null || encoding.indexOf("gzip") < 0) |
45 | 0 | return false; |
46 | ||
47 | // Handle IE specific hacks | |
48 | ||
49 | 0 | String userAgent = request.getHeader("User-Agent"); |
50 | 0 | int ieIndex = (userAgent != null) ? userAgent.indexOf("MSIE") : -1; |
51 | 0 | if (ieIndex > -1) |
52 | { | |
53 | 0 | float version = -1; |
54 | ||
55 | try | |
56 | { | |
57 | 0 | version = Float.parseFloat(userAgent.substring(ieIndex + 4, ieIndex + 8)); |
58 | 0 | } catch (NumberFormatException nf) {nf.printStackTrace();} |
59 | ||
60 | 0 | if (version >= MIN_IE_VERSION) |
61 | 0 | return true; |
62 | ||
63 | 0 | if (userAgent.indexOf(MSIE_6_COMPATIBLE_STRING) > -1) |
64 | 0 | return true; |
65 | ||
66 | // else false | |
67 | ||
68 | 0 | return false; |
69 | } | |
70 | ||
71 | 0 | return true; |
72 | } | |
73 | ||
74 | /** | |
75 | * Based on the given type of content, determines if compression is appropriate. The biggest | |
76 | * thing it does is make sure that image content isn't compressed as that kind of content | |
77 | * is already compressed fairly well. | |
78 | * | |
79 | * @param contentType | |
80 | * The content type to check. (ie "text/javascript","text/html", etc..) | |
81 | * | |
82 | * @return True if compression is appropriate for the content specified, false otherwise. | |
83 | */ | |
84 | public static boolean shouldCompressContentType(String contentType) | |
85 | { | |
86 | 0 | if (contentType == null) |
87 | 0 | return false; |
88 | ||
89 | 0 | return contentType.indexOf("javascript") > -1 |
90 | || contentType.indexOf("css") > -1 | |
91 | || contentType.indexOf("html") > -1 | |
92 | || contentType.indexOf("text") > -1; | |
93 | } | |
94 | } |