1 // Copyright (c) 2000 Just Objects B.V. <just@justobjects.nl>
2 // Distributable under LGPL license. See terms of license at gnu.org.
3 
4 package nl.justobjects.pushlet.util;
5 
6 import javax.servlet.http.HttpServletRequest;
7 import javax.servlet.http.HttpServletResponse;
8 
9 
10/**
11 * Servlet utilities.
12 *
13 * @author Just van den Broecke - Just Objects &copy;
14 * @version $Id: Servlets.java,v 1.2 2007/11/23 21:10:17 justb Exp $
15 */
16public class Servlets {
17
18    /**
19     * Get parameter; if not set or empty return null.
20     */
21    public static String getParameter(HttpServletRequest aRequest, String aName) {
22        return getParameter(aRequest, aName, null);
23    }
24
25    /**
26     * Get parameter; if not set or empty return specified default value.
27     */
28    public static String getParameter(HttpServletRequest aRequest, String aName, String aDefault) {
29        String value = aRequest.getParameter(aName);
30        if (value == null || value.length() == 0) {
31            value = aDefault;
32        }
33        return value;
34    }
35
36    /**
37     * Set HTTP headers to prevent caching.
38     */
39    public static void setNoCacheHeaders(HttpServletResponse aResponse) {
40        // Set to expire far in the past.
41        aResponse.setHeader("Expires", "Sat, 6 May 1995 12:00:00 GMT");
42
43        // Set standard HTTP/1.1 no-cache headers.
44        aResponse.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");
45
46        // Set IE extended HTTP/1.1 no-cache headers (use addHeader).
47        aResponse.addHeader("Cache-Control", "post-check=0, pre-check=0");
48
49        // Set standard HTTP/1.0 no-cache header.
50        aResponse.setHeader("Pragma", "no-cache");
51
52    }
53
54}
55
56/*
57 * $Log: Servlets.java,v $
58 * Revision 1.2  2007/11/23 21:10:17  justb
59 * add hooks for custom logging (you can override DefaultLogger in pushlet.properties)
60 *
61 * Revision 1.1  2004/09/20 22:01:40  justb
62 * more changes for new protocol
63 *
64 *
65 */
66
67
68