org.directwebremoting.util.BrowserDetect Maven / Gradle / Ivy

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DWR is easy Ajax for Java. It makes it simple to call Java code directly from Javascript. It gets rid of almost all the boiler plate code between the web browser and your Java code.
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/*
 * 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.
 */
package org.directwebremoting.util;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Various functions to do with working out what is at the other end of the
 * wire, and what it can do.
 * 
 * Version number documentation
 * 
 * Firefox
 * Quick summary:
 * 

 * Firefox 1.0.0 = Gecko/20041108 - 20050405
 * 
Firefox 1.0.8 = Gecko/20060410 - 20060418
 * 
Firefox 1.4.0 = Gecko/20050908
 * 
 * 
 * Safari
 * Quick summary:
 * 

 * Jaguar  = 10.2.x  = Safari 1.0.x = WebKit/85
 * 
Panther = 10.3.0+ = Safari 1.1.x = WebKit/100
 * 
Panther = 10.3.4+ = Safari 1.2.x = WebKit/125
 * 
Panther = 10.3.9+ = Safari 1.3.x = WebKit/312
 * 
Tiger   = 10.4.x  = Safari 2.0.x = WebKit/412-419
 * 
Tiger   = 10.4.11 = Safari 3.0.x = WebKit/523
 * 
Leopard = 10.5.x  = Safari 3.0.x = WebKit/523
 * 
Windows           = Safari 3.0.x = WebKit/523
 * 
Leopard = 10.5.x  = Safari 3.1.x = WebKit/525-526
 * 
 * 
 * For full information see the Safari and WebKit Version Information:
 * at Apple
 * Developer Connection and for browsers in general, see this fairly complete
 * list of
 * user agent strings.
 * @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;
        }
        if (atLeast(request, UserAgent.Firefox, 3))
        {
            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;

        case Firefox:
            realVersion = getMajorVersionAssumingFirefox(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#AppleWebKit}
     */
    private static int getMajorVersionAssumingFirefox(String userAgent)
    {
        int firefoxPos = userAgent.indexOf("Firefox");
        if (firefoxPos == -1)
        {
            return -1;
        }

        return parseNumberAtStart(userAgent.substring(firefoxPos + 8));
    }

    /**
     * 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 + ")";
    }

    /**
     * @deprecated This method is for debugging only
     */
    @Deprecated
    public static void debugBrowserVersions(HttpServletRequest request)
    {
        String userAgent = request.getHeader("user-agent");

        log.debug("User-Agent: " + userAgent);
        log.debug("Version assuming IE: " + getMajorVersionAssumingIE(userAgent));
        log.debug("Version assuming Gecko: " + getMajorVersionAssumingGecko(userAgent));
        log.debug("Version assuming Opera: " + getMajorVersionAssumingOpera(userAgent));
        log.debug("Version assuming WebKit: " + getMajorVersionAssumingAppleWebKit(userAgent));
    }

    /**
     * The log stream
     */
    private static final Log log = LogFactory.getLog(BrowserDetect.class);
}