Java tutorial
/* * 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, }