Seeking a JSP Alternative to ASP Request.ServerVariables

[jeremybwilson]

I would like to try and find an alternative solution in JSP to the following ASP code sample.


<%
userAgent = Request.ServerVariables("HTTP_USER_AGENT")
isMobile = false
i
f((InStr(userAgent, "AvantGo") > 0) OR (InStr(userAgent, "Windows CE") > 0) OR (InStr(userAgent, "NetFront") > 0) OR (InStr(userAgent, "BlackBerry") > 0) ) then
isMobile = true
end if
if isMobile then
response.redirect("http://www.namesandnumbers.com/mobile")
end if
%>


I'm also wondering if the effort involved in doing this wouldn't just be time better spent on developing an HTML solution with a handheld CSS file fed dynamically to the page by some JavaScript browser/client detection. Probably a question for another forum here...

As always, thanks in advance for any responses.

[chazzy]

http://java.sun.com/javaee/5/docs/api/javax/servlet/http/HttpServletRequest.html

request.getHeader("HTTP_USER_AGENT")

[jeremybwilson]

Well, I was able to cook something up in JSP but it doesn't seem to be catching and redirecting. I am actually trying to detect two different ways but neither redirects. In both attempts, I threw in an additional else statement to try and catch my local client Firefox 3 (Mozilla/5.0) and still all I get is the "Hello World" (at the end of the statement) printed out to the page.

Can anyone tell me where I am going wrong here? Code included. FWIW, the first three lines are code snippets used frequently in our OpenCMS 6 environment.

<%@ page session="false" %>
<%@ taglib prefix="cms" uri="http://www.opencms.org/taglib/cms" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core" %>

<%
String accept = request.getHeader("accept");
String user_agent = request.getHeader("user-agent");
String accept_charset = request.getHeader("accept-charset");
String accept_language = request.getHeader("accept-language");
String x_wap_profile = request.getHeader("x-wap-profile");
String profile = request.getHeader("profile");
%>
<%
if ((user_agent == ("AvantGo")) || (user_agent == ("Windows CE")) || (user_agent == ("NetFront")) || (user_agent == ("BlackBerry"))) {
String redirectURL = "http://www.xbox.com";
response.sendRedirect(redirectURL);
}
else if (user_agent == ("Mozilla/5.0")) {
%>
<p>You are using Firefox</p>
<% } else { %>
<p>Hello World</p>
<% } %>

<%
if ((user_agent.indexOf("AvantGo") > 0) || (user_agent.indexOf("Windows CE") > 0) || (user_agent.indexOf("NetFront") > 0) || (user_agent.indexOf("BlackBerry") > 0)) {
String redirectURL = "http://www.xbox.com";
response.sendRedirect(redirectURL);
}
else if (user_agent.indexOf("Mozilla/5.0") > 0) {
%>
<p>You are using Firefox</p>
<% } else { %>
<p>Hello World</p>
<% } %>

On a side note, I am curious about something here. Me personally, with regards to JSP, I am a noob but I manage to function with ASP and PHP. My last year spent trying to piecemeal learn JSP is just killing me, as I seem to have difficulty finding well flushed out examples of how to do some of the most basic tasks, tasks that I see being done with classic ASP or PHP, in JSP. At least in terms of web-based samples/examples of server-side JSP scripting.

I'm actually still confused about what JSP exactly is, as many examples I see seem to include what looks to me like object-oriented Java code. Is this JSP or something different? Beans?

At this point in this post I should probably just come right out and ask for a "beginning JSP" book recommendation.

Does anyone else feel like they ran into this problem when attempting to learn JSP from scratch with no previous programming background?

[chazzy]

use .equals or .equalsIgnoreCase

[jeremybwilson]

use .equals or .equalsIgnoreCase

Thanks Chazzy.

However, I'm still running into a wall here.

This is what I tried next. I also attempted the same with .equals.


<%
if ((user_agent.equalsIgnoreCase("AvantGo")) || (user_agent.equalsIgnoreCase("Windows CE")) || (user_agent.equalsIgnoreCase("NetFront")) || (user_agent.equalsIgnoreCase("BlackBerry"))) {
String redirectURL = "http://www.xbox.com";
response.sendRedirect(redirectURL);
}
else if (user_agent.equalsIgnoreCase("Mozilla")) {
%>
<p>You are using Firefox</p>
<% } else { %>
<p>Hello World</p>
<% } %>

I am still not having any lucky making the redirect behavior work which tells me that I am not properly comparing these string values.

[jeremybwilson]

Okay, so I'm sure that I'm properly declaring my String user_agent variable.

So I'm good down to at least here: <%@ page session="false" %>
<%@ taglib prefix="cms" uri="http://www.opencms.org/taglib/cms" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core" %>

<%
String user_agent = request.getHeader("user-agent");
%>

What I don't understand is why aren't my comparisons returning any results when a quick scriptlet of the user_agent string returns immediate results.

<%= user_agent%>

Which returns user-agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.0.11) Gecko/2009060215 Firefox/3.0.11

It seems as though (user_agent == ("Any Value")) will only return false.

[criterion9]

Try contains: http://java.sun.com/j2se/1.5.0/docs/api/java/lang/String.html#contains(java.lang.CharSequence)

[jeremybwilson]

Thanks criterion, that did the trick. Can anyone point me to a specific reason as to why my attempts to declare a string variable called "user_agent" and populate it with information gleaned from request.getHeader("user-agent"); only returned false when attempting comparisons using .equals. and .equalsIgnoreCase?

[criterion9]

What you spit out was a huge string that contained the characters you were looking for. .equals and .equalsIgnoreCase only check for equality. You were checking if the string contained another string. Does that make sense?

[jeremybwilson]

Yes, sorry, the differences between .equals and .equalsIgnoreCase versus .contains were not apparent to me. Namely the fact that both of the .equals examples I just gave, are looking for complete equality. The moment I switched it out it for .contains , the script worked flawlessly.

By the way, here is my final working product. Simple but does the job.

<%@ page session="false" %>
<%@ taglib prefix="cms" uri="http://www.opencms.org/taglib/cms" %>

<%
String user_agent = request.getHeader("user-agent");
%>
<%
if ((user_agent.contains("AvantGo")) || (user_agent.contains("Windows CE")) || (user_agent.contains("NetFront")) || (user_agent.contains("BlackBerry"))) {
String redirectURL = "http://www.xbox.com/mobile";
response.sendRedirect(redirectURL);
} else if ((user_agent.contains("Mozilla")) || (user_agent.contains("MSIE")) || (user_agent.contains("Opera"))) {
// out.println("<p>You are using Firefox</p>");
String redirectURL = "http://www.xbox.com";
response.sendRedirect(redirectURL);
} else {
out.println("<p>Hello world</p>");
}
%>

[JavaServlet]

I would recommend not putting logic in JSP and keeping it in java classes only.
JSP should be for presentation only.