1 //
2 // ========================================================================
3 // Copyright (c) 1995-2015 Mort Bay Consulting Pty. Ltd.
4 // ------------------------------------------------------------------------
5 // All rights reserved. This program and the accompanying materials
6 // are made available under the terms of the Eclipse Public License v1.0
7 // and Apache License v2.0 which accompanies this distribution.
8 //
9 // The Eclipse Public License is available at
10 // http://www.eclipse.org/legal/epl-v10.html
11 //
12 // The Apache License v2.0 is available at
13 // http://www.opensource.org/licenses/apache2.0.php
14 //
15 // You may elect to redistribute this code under either of these licenses.
16 // ========================================================================
17 //
18
19 package org.eclipse.jetty.servlets;
20
21 import java.io.IOException;
22 import java.util.ArrayList;
23 import java.util.List;
24
25 import javax.servlet.RequestDispatcher;
26 import javax.servlet.ServletContext;
27 import javax.servlet.ServletException;
28 import javax.servlet.http.HttpServlet;
29 import javax.servlet.http.HttpServletRequest;
30 import javax.servlet.http.HttpServletResponse;
31
32 import org.eclipse.jetty.util.URIUtil;
33
34 /**
35 * <p>This servlet may be used to concatenate multiple resources into
36 * a single response.</p>
37 * <p>It is intended to be used to load multiple
38 * javascript or css files, but may be used for any content of the
39 * same mime type that can be meaningfully concatenated.</p>
40 * <p>The servlet uses {@link RequestDispatcher#include(javax.servlet.ServletRequest, javax.servlet.ServletResponse)}
41 * to combine the requested content, so dynamically generated content
42 * may be combined (Eg engine.js for DWR).</p>
43 * <p>The servlet uses parameter names of the query string as resource names
44 * relative to the context root. So these script tags:</p>
45 * <pre>
46 * <script type="text/javascript" src="../js/behaviour.js"></script>
47 * <script type="text/javascript" src="../js/ajax.js&/chat/chat.js"></script>
48 * <script type="text/javascript" src="../chat/chat.js"></script>
49 * </pre>
50 * <p>can be replaced with the single tag (with the {@code ConcatServlet}
51 * mapped to {@code /concat}):</p>
52 * <pre>
53 * <script type="text/javascript" src="../concat?/js/behaviour.js&/js/ajax.js&/chat/chat.js"></script>
54 * </pre>
55 * <p>The {@link ServletContext#getMimeType(String)} method is used to determine the
56 * mime type of each resource. If the types of all resources do not match, then a 415
57 * UNSUPPORTED_MEDIA_TYPE error is returned.</p>
58 * <p>If the init parameter {@code development} is set to {@code true} then the servlet
59 * will run in development mode and the content will be concatenated on every request.</p>
60 * <p>Otherwise the init time of the servlet is used as the lastModifiedTime of the combined content
61 * and If-Modified-Since requests are handled with 304 NOT Modified responses if
62 * appropriate. This means that when not in development mode, the servlet must be
63 * restarted before changed content will be served.</p>
64 */
65 public class ConcatServlet extends HttpServlet
66 {
67 private boolean _development;
68 private long _lastModified;
69
70 @Override
71 public void init() throws ServletException
72 {
73 _lastModified = System.currentTimeMillis();
74 _development = Boolean.parseBoolean(getInitParameter("development"));
75 }
76
77 /*
78 * @return The start time of the servlet unless in development mode, in which case -1 is returned.
79 */
80 @Override
81 protected long getLastModified(HttpServletRequest req)
82 {
83 return _development ? -1 : _lastModified;
84 }
85
86 @Override
87 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
88 {
89 String query = request.getQueryString();
90 if (query == null)
91 {
92 response.sendError(HttpServletResponse.SC_NO_CONTENT);
93 return;
94 }
95
96 List<RequestDispatcher> dispatchers = new ArrayList<>();
97 String[] parts = query.split("\\&");
98 String type = null;
99 for (String part : parts)
100 {
101 String path = URIUtil.canonicalPath(URIUtil.decodePath(part));
102 if (path == null)
103 {
104 response.sendError(HttpServletResponse.SC_NOT_FOUND);
105 return;
106 }
107
108 // Verify that the path is not protected.
109 if (startsWith(path, "/WEB-INF/") || startsWith(path, "/META-INF/"))
110 {
111 response.sendError(HttpServletResponse.SC_NOT_FOUND);
112 return;
113 }
114
115 String t = getServletContext().getMimeType(path);
116 if (t != null)
117 {
118 if (type == null)
119 {
120 type = t;
121 }
122 else if (!type.equals(t))
123 {
124 response.sendError(HttpServletResponse.SC_UNSUPPORTED_MEDIA_TYPE);
125 return;
126 }
127 }
128
129 RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(path);
130 if (dispatcher != null)
131 dispatchers.add(dispatcher);
132 }
133
134 if (type != null)
135 response.setContentType(type);
136
137 for (RequestDispatcher dispatcher : dispatchers)
138 dispatcher.include(request, response);
139 }
140
141 private boolean startsWith(String path, String prefix)
142 {
143 // Case insensitive match.
144 return prefix.regionMatches(true, 0, path, 0, prefix.length());
145 }
146 }