1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
|
// Copyright (C) 2008 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.gwtexpui.server;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Forces GWT resources to cache for a very long time.
* <p>
* GWT compiled JavaScript and ImageBundles can be cached indefinitely by a
* browser and/or an edge proxy, as they never contain user-specific data and
* are named by a unique checksum. If their content is ever modified then the
* URL changes, so user agents would request a different resource. We force
* these resources to have very long expiration times.
* <p>
* To use, add the following block to your <code>web.xml</code>:
*
* <pre>
* <filter>
* <filter-name>CacheControl</filter-name>
* <filter-class>com.google.gwtexpui.server.CacheControlFilter</filter-class>
* </filter>
* <filter-mapping>
* <filter-name>CacheControl</filter-name>
* <url-pattern>/*</url-pattern>
* </filter-mapping>
* </pre>
*/
public class CacheControlFilter implements Filter {
public void init(final FilterConfig config) {
}
public void destroy() {
}
public void doFilter(final ServletRequest sreq, final ServletResponse srsp,
final FilterChain chain) throws IOException, ServletException {
final HttpServletRequest req = (HttpServletRequest) sreq;
final HttpServletResponse rsp = (HttpServletResponse) srsp;
final String pathInfo = pathInfo(req);
if (cacheForever(pathInfo, req)) {
CacheHeaders.setCacheable(req, rsp, 365, TimeUnit.DAYS);
} else if (nocache(pathInfo)) {
CacheHeaders.setNotCacheable(rsp);
}
chain.doFilter(req, rsp);
}
private static boolean cacheForever(final String pathInfo,
final HttpServletRequest req) {
if (pathInfo.endsWith(".cache.html")) {
return true;
} else if (pathInfo.endsWith(".cache.gif")) {
return true;
} else if (pathInfo.endsWith(".cache.png")) {
return true;
} else if (pathInfo.endsWith(".cache.css")) {
return true;
} else if (pathInfo.endsWith(".cache.jar")) {
return true;
} else if (pathInfo.endsWith(".cache.swf")) {
return true;
} else if (pathInfo.endsWith(".nocache.js")) {
final String v = req.getParameter("content");
return v != null && v.length() > 20;
}
return false;
}
private static boolean nocache(final String pathInfo) {
if (pathInfo.endsWith(".nocache.js")) {
return true;
}
return false;
}
private static String pathInfo(final HttpServletRequest req) {
final String uri = req.getRequestURI();
final String ctx = req.getContextPath();
return uri.startsWith(ctx) ? uri.substring(ctx.length()) : uri;
}
}
|
