How can I get client information such as OS and browser

I'm using JSP, Servlet to develop my web application.

I want to get client information such as: operation system, browser, resolution, ... whenever a client is using my website.

Your best bet is User-Agent header. You can get it like this in JSP or Servlet,

String userAgent = request.getHeader("User-Agent");

The header looks like this,

User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.0.13) Gecko/2009073021 Firefox/3.0.13

It provides detailed information on browser. However, it's pretty much free format so it's very hard to decipher every single one. You just need to figure out which browsers you will support and write parser for each one. When you try to identify the version of browser, always check newer version first. For example, IE6 user-agent may contain IE5 for backward compatibility. If you check IE5 first, IE6 will be categorized as IE5 also.

You can get a full list of all user-agent values from this web site,

http://www.user-agents.org/

With User-Agent, you can tell the exact version of the browser. You can get a pretty good idea on OS but you may not be able to distinguish between different versions of the same OS, for example, Windows NT and 2000 may use same User-Agent.

There is nothing about resolution. However, you can get this with Javascript on an AJAX call.

In Java there is no direct way to get browser and OS related information.

But to get this few third-party tools are available.

Instead of trusting third-party tools, I suggest you to parse the user agent.

String  browserDetails  =   request.getHeader("User-Agent");

By doing this you can separate the browser details and OS related information easily according to your requirement. PFB the snippet for reference (you can replace this with a switch case as well).

        String  browserDetails  =   request.getHeader("User-Agent");
        String  userAgent       =   browserDetails;
        String  user            =   userAgent.toLowerCase();
    
        String os = "";
        String browser = "";

        log.info("User Agent for the request is===>"+browserDetails);
        //=================OS=======================
         if (userAgent.toLowerCase().indexOf("windows") >= 0 )
         {
             os = "Windows";
         } else if(userAgent.toLowerCase().indexOf("mac") >= 0)
         {
             os = "Mac";
         } else if(userAgent.toLowerCase().indexOf("x11") >= 0)
         {
             os = "Unix";
         } else if(userAgent.toLowerCase().indexOf("android") >= 0)
         {
             os = "Android";
         } else if(userAgent.toLowerCase().indexOf("iphone") >= 0)
         {
             os = "IPhone";
         }else{
             os = "UnKnown, More-Info: "+userAgent;
         }
         //===============Browser===========================
        if (user.contains("msie"))
        {
            String substring=userAgent.substring(userAgent.indexOf("MSIE")).split(";")[0];
            browser=substring.split(" ")[0].replace("MSIE", "IE")+"-"+substring.split(" ")[1];
        } else if (user.contains("safari") && user.contains("version"))
        {
            browser=(userAgent.substring(userAgent.indexOf("Safari")).split(" ")[0]).split("/")[0]+"-"+(userAgent.substring(userAgent.indexOf("Version")).split(" ")[0]).split("/")[1];
        } else if ( user.contains("opr") || user.contains("opera"))
        {
            if(user.contains("opera"))
                browser=(userAgent.substring(userAgent.indexOf("Opera")).split(" ")[0]).split("/")[0]+"-"+(userAgent.substring(userAgent.indexOf("Version")).split(" ")[0]).split("/")[1];
            else if(user.contains("opr"))
                browser=((userAgent.substring(userAgent.indexOf("OPR")).split(" ")[0]).replace("/", "-")).replace("OPR", "Opera");
        } else if (user.contains("chrome"))
        {
            browser=(userAgent.substring(userAgent.indexOf("Chrome")).split(" ")[0]).replace("/", "-");
        } else if ((user.indexOf("mozilla/7.0") > -1) || (user.indexOf("netscape6") != -1)  || (user.indexOf("mozilla/4.7") != -1) || (user.indexOf("mozilla/4.78") != -1) || (user.indexOf("mozilla/4.08") != -1) || (user.indexOf("mozilla/3") != -1) )
        {
            //browser=(userAgent.substring(userAgent.indexOf("MSIE")).split(" ")[0]).replace("/", "-");
            browser = "Netscape-?";
                  
        } else if (user.contains("firefox"))
        {
            browser=(userAgent.substring(userAgent.indexOf("Firefox")).split(" ")[0]).replace("/", "-");
        } else if(user.contains("rv"))
        {
            browser="IE-" + user.substring(user.indexOf("rv") + 3, user.indexOf(")"));
        } else
        {
            browser = "UnKnown, More-Info: "+userAgent;
        }
        log.info("Operating System======>"+os);
        log.info("Browser Name==========>"+browser);