Browser detection
/*
* Copyright 2005 Joe Walker
*
* 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.
*/
import javax.servlet.http.HttpServletRequest;
/**
* Various functions to do with working out what is at the other end of the
* wire, and what it can do.
*
* <h2>Version number documentation</h2>
*
* <h3>Safari</h3>
* <p>Quick summary:
* <ul>
* <li>Jaguar = 10.2.x = Safari 1.0.x = WebKit/85
* <li>Panther = 10.3.0+ = Safari 1.1.x = WebKit/100
* <li>Panther = 10.3.4+ = Safari 1.2.x = WebKit/125
* <li>Panther = 10.3.9+ = Safari 1.3.x = WebKit/312
* <li>Tiger = 10.4.x = Safari 2.0.x = WebKit/412-419
* <li>Tiger = 10.4.11 = Safari 3.0.x = WebKit/523
* <li>Leopard = 10.5.x = Safari 3.0.x = WebKit/523
* <li>Windows = Safari 3.0.x = WebKit/523
* <li>Leopard = 10.5.x = Safari 3.1.x = WebKit/525-526
* </ul>
*
* <p>For full information see the Safari and WebKit Version Information:
* <a href="http://developer.apple.com/internet/safari/uamatrix.html">at Apple
* Developer Connection</a> and for browsers in general, see this fairly complete
* <a href="http://www.useragentstring.com/pages/useragentstring.php">list of
* user agent strings</a>.</p>
* @author Joe Walker [joe at getahead dot ltd dot uk]
*/
public class BrowserDetect
{
/**
* How many connections can this browser open simultaneously?
* @param request The request so we can get at the user-agent header
* @return The number of connections that we think this browser can take
*/
public static int getConnectionLimit(HttpServletRequest request)
{
if (atLeast(request, UserAgent.IE, 8))
{
return 6;
}
else if (atLeast(request, UserAgent.AppleWebKit, 8))
{
return 4;
}
else if (atLeast(request, UserAgent.Opera, 9))
{
return 4;
}
else
{
return 2;
}
}
/**
* Does this web browser support comet?
* @param request The request so we can get at the user-agent header
* @return True if long lived HTTP connections are supported
*/
public static boolean supportsComet(HttpServletRequest request)
{
String userAgent = request.getHeader("user-agent");
// None of the non-iPhone mobile browsers that I've tested support comet
if (userAgent.contains("Symbian"))
{
return false;
}
// We need to test for other failing browsers here
return true;
}
/**
* Check that the user-agent string indicates some minimum browser level
* @param request The browsers request
* @param requiredUserAgent The UA required
* @return true iff the browser matches the spec.
*/
public static boolean atLeast(HttpServletRequest request, UserAgent requiredUserAgent)
{
return atLeast(request, requiredUserAgent, -1);
}
/**
* Check that the user-agent string indicates some minimum browser level
* @param request The browsers request
* @param requiredUserAgent The UA required. Currently this is major version only
* @param requiredVersion The version required, or -1 if versions are not important
* @return true iff the browser matches the spec.
*/
public static boolean atLeast(HttpServletRequest request, UserAgent requiredUserAgent, int requiredVersion)
{
String userAgent = request.getHeader("user-agent");
int realVersion;
switch (requiredUserAgent)
{
case IE:
realVersion = getMajorVersionAssumingIE(userAgent);
break;
case Gecko:
realVersion = getMajorVersionAssumingGecko(userAgent);
break;
case Opera:
realVersion = getMajorVersionAssumingOpera(userAgent);
break;
case AppleWebKit:
realVersion = getMajorVersionAssumingAppleWebKit(userAgent);
break;
default:
throw new UnsupportedOperationException("Detection of " + requiredUserAgent + " is not supported yet.");
}
return realVersion >= requiredVersion;
}
/**
* Check {@link #atLeast(HttpServletRequest, UserAgent)} for
* {@link UserAgent#AppleWebKit}
*/
private static int getMajorVersionAssumingAppleWebKit(String userAgent)
{
int webKitPos = userAgent.indexOf("AppleWebKit");
if (webKitPos == -1)
{
return -1;
}
return parseNumberAtStart(userAgent.substring(webKitPos + 12));
}
/**
* Check {@link #atLeast(HttpServletRequest, UserAgent)} for
* {@link UserAgent#Opera}
*/
private static int getMajorVersionAssumingOpera(String userAgent)
{
int operaPos = userAgent.indexOf("Opera");
if (operaPos == -1)
{
return -1;
}
return parseNumberAtStart(userAgent.substring(operaPos + 6));
}
/**
* Check {@link #atLeast(HttpServletRequest, UserAgent)} for
* {@link UserAgent#Gecko}
*/
private static int getMajorVersionAssumingGecko(String userAgent)
{
int geckoPos = userAgent.indexOf(" Gecko/20");
if (geckoPos == -1 || userAgent.contains("WebKit/"))
{
return -1;
}
return parseNumberAtStart(userAgent.substring(geckoPos + 7));
}
/**
* Check {@link #atLeast(HttpServletRequest, UserAgent)} for
* {@link UserAgent#IE}
*/
private static int getMajorVersionAssumingIE(String userAgent)
{
int msiePos = userAgent.indexOf("MSIE ");
if (msiePos == -1 || userAgent.contains("Opera"))
{
return -1;
}
return parseNumberAtStart(userAgent.substring(msiePos + 5));
}
/**
* We've found the start of a sequence of numbers, what is it as an int?
*/
private static int parseNumberAtStart(String numberString)
{
if (numberString == null || numberString.length() == 0)
{
return -1;
}
int endOfNumbers = 0;
while (Character.isDigit(numberString.charAt(endOfNumbers)))
{
endOfNumbers++;
}
try
{
return Integer.parseInt(numberString.substring(0, endOfNumbers));
}
catch (NumberFormatException ex)
{
return -1;
}
}
/**
* This method is for debugging only
*/
public static String getUserAgentDebugString(HttpServletRequest request)
{
String userAgent = request.getHeader("user-agent");
int version = getMajorVersionAssumingIE(userAgent);
if (version != -1)
{
return "IE/" + version;
}
version = getMajorVersionAssumingGecko(userAgent);
if (version != -1)
{
return "Gecko/" + version;
}
version = getMajorVersionAssumingAppleWebKit(userAgent);
if (version != -1)
{
return "WebKit/" + version;
}
version = getMajorVersionAssumingOpera(userAgent);
if (version != -1)
{
return "Opera/" + version;
}
return "Unknown: (" + userAgent + ")";
}
}
/*
* Copyright 2005 Joe Walker
*
* 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.
*/
/**
* @author Joe Walker [joe at getahead dot ltd dot uk]
*/
enum UserAgent
{
IE,
Opera,
Gecko,
AppleWebKit,
}
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