General JSP-Servlet question

Hi! All
I created a web application using JSP and without using a single servlet. A friend of mine suggests that JSP should never be used by itself. JSP and servlets should go hand in hand.
Is there a drawback to the application created using only JSP?
Please advice.

Whenever you are writing a web application,you should use MVC architecture. That is a better approach for performance and scalability
To quote from J2EE Patterns Catalog
<MVC>
Several problems can arise when applications contain a mixture of data access code, business logic code, and presentation code. Such applications are difficult to maintain, because interdependencies between all of the components cause strong ripple effects whenever a change is made anywhere. High coupling makes classes difficult or impossible to reuse because they depend on so many other classes. Adding new data views often requires reimplementing or cutting and pasting business logic code, which then requires maintenance in multiple places. Data access code suffers from the same problem, being cut and pasted among business logic methods.
The Model-View-Controller design pattern solves these problems by decoupling data access, business logic, and data presentation and user interaction.
</MVC>

Similar Messages

Login Problems and General JSP Security Questions

I'm new to this, so I'm still not sure if I'm approaching this problem the right way. But after a user logs in with the correct username/password, I create a session attribute like so:
session.setAttribute("loggedIn", "true");
Now, inside of every other JSP page I make the following check before the user can continue:
<%
          String loggedIn = (String)(session.getAttribute("loggedIn"));
          if( loggedIn == null || !loggedIn.equals("true")) {
%>
               <jsp:forward page="../login.html" />
<%
%>
And to logout I simply set the attribute to false:
session.setAttribute("loggedIn", "false");
Unfortunately, this doesn't work very well. It seems to be very inconsistent. Does anyone know of a better, not-so-difficult, method to do this? Or do you see any problems with what I have?
Another thing, how do I prevent a user from accessing my JSP directory? For example, I have my JSPs stored in public_html/jsp directory, how do I prevent someone from simply visiting www.mysite.com/jsp without using the web.xml file?

I use sessions in this way without any problems, what are the inconsistencies??
You can protect folders with Tomcat security but it requires XML configuration.

Newbie JSP/Servlet general question

Hi,
I am currently studying the life cycle of a JSP page from the Java EE 5 Tutorial (http://java.sun.com/javaee/5/docs/tutorial/doc/bnahe.html). This document says that: "+If an instance of the JSP pages servlet does not exist, the container loads the JSP pages servlet class, instantiates an instance of the servlet class, initializes the servlet instance by calling the jspInit method+".
My two questions are:
i) Does this JSP servlet implement the HttpJspPage interface defined in javax.servlet.jsp?
ii) Does Struts and Spring MVC provide such JSP servlet Java classes implementations or are these part of other packages? If not, which packages offer such implementations?
Thanks,
J.

Jrm wrote:
Hi,
I am currently studying the life cycle of a JSP page from the Java EE 5 Tutorial (http://java.sun.com/javaee/5/docs/tutorial/doc/bnahe.html). This document says that: "+If an instance of the JSP pages servlet does not exist, the container loads the JSP pages servlet class, instantiates an instance of the servlet class, initializes the servlet instance by calling the jspInit method+".
My two questions are:
i) Does this JSP servlet implement the HttpJspPage interface defined in javax.servlet.jsp?Yes.
>
ii) Does Struts and Spring MVC provide such JSP servlet Java classes implementations or are these part of other packages? If not, which packages offer such implementations?No, the implementation for the JSP servlet is usually provided by the Servlet Container, not a framework, since the Servlet Container is responsible for creating and compiling the JSP.
>
Thanks,
J.

Jsp,servlet,bean question,please help

The Tomcat Web server set up like this.......
The directory structure is
e:/sampleapp/WEB-INF/classes
/lib
And the web.xml is in the WEB-INF for the use of ay potential servlet.
The basic understanding is that all the .java files go into the WEB-INF directory and the .class files go into the classes directory.
All the .jsp files go into the sampleapp directory.Till here is correct I feel.
Now for my qustion......
I plan to use jsp,servlet and beans for a potential web application...,where do all these files go?,just the same as above or is there a difference.
Hope that I have given a reasonable explaination to my question.
Thanks for any replies
AS

All of your compiled servlet and java bean (java
classes in general) will be placed into the following
directory (under a directory structure matching the
java package they are in):
e:/sampleapp/WEB-INF/classesAll of your .jar files that are used as libraries (not
your .jar files for applets):
e:/sampleapp/WEB-INF/libAll of the rest of your JSP files, javascript files,
HTML files, JAR files, images files, etc. will go into
the following directory:
e:/sampleappYou must make sure you put your sampleapp directory
where tomcat can load it. Or use the admin tool to
load it. If you make a .WAR file with a corresponding
web.xml file in it, it will simplify loading it into
tomcat. It also will help you do your servlet
mappings, etc. I hope this helps.Thanks for your timely response.To add to it,let me tell you.
The <b>bean</b> files are put into a package right,so they should be put into the WEB-INF/classes/<package name>
What about The <b> servlet </b> files...... they are just put into the WEB-INF/classes/ directory????
Kindly let me know.
Thanks
AS

Question about domain name/JSP, servlets

I have a web host which publishes my pages, say www.zzz.com. I want to use JSP/Servlets on my machine which is using Apache Tomcat. Here's the problem, if I link a JSP/Servlet from www.zzz.com, the user will see my IP, i.e. 37.28.18.102/servlets/Calculations
Is there a way where the people's browser's URL text field will always be www.zzz.com even if the page is located on my server?

Try using Frameset where top frame is always www.xxx.com and child frame can be anywhere

How to implement this function in JSP/Servlet env?

Hi all,
I working on a project, it provides functionality to upload file using JSP/Servlet. In the first JSP page, there is file location and submit button. After user select a file to upload and click submit button, a message, like "sending file to XXXX", will be shown on the screen. Once uploading and validation are done on the server-side, a successful/error msg will be shown to user.
Here I have a question for the "sending..." msg and the successful/error msg. They should be put in one jsp page or in two separate page? how to implement them?
Thanks for any help!
Tranquil

For the sending message... Well, the thing is, when you click submit, it's sending the file to the server and the server is processing it, and this is all done before the "complete" page is sent to the server. So one would need to use some Javascript on the page before the actual submit happens to show some message. This is done on Ebay when you put something for sale, you can upload an image, and there is a little popup message telling you that it's uploading, and it is removed when the process is done. Now, I'm not sure the exact details of how this works, but my educated guess is this:
1) The onsubmit function of the form checks that the file upload fields have a value (no need to popup a message if no file upload, since that's what usually takes the time, although it could just be assumed there is a file). If a file is to be uploaded, or just want to show the message anyway, a new popup window is opened with the window.open method and the "sending" message is shown (either written via Javascript or just load a small web page to the window).
2) The popup window, since you can't transfer the window object from the form page to the next page, has to check window.opener for some value that the success/error page would have to set. The success/error page could use it's body onload function to set a variable in it's own window object to denote that the page is loaded. The popup window can use a looping check using setTimeout or setInterval in Javascript to check for window.opener.isLoadedVariable to be present, and if so, close itself.
I've never done that, but I see no reason why it wouldn't work.

File upload and download using jsp/servlets

How to upload any file to the server using jsp/servlets. . Help me out

You can also try the Jenkov HTTP Multipart File Upload. It's a servlet filter that is easy to add to your web-project. After adding it, you can access both request parameters and the uploaded files easily. It's more transparent than Apache Commons File Upload. There is sufficient documentation to get you started, and there is a forum if you have any questions.
Jenkov HTTP Multipart File Upload is available under the Apache license, meaning its free to use.

Jsp / Servlet / bean / upload

Hello,
I use a jsp to enter several fields. These fields are sent to a servlet by using a bean (recorded in the current session). Until now there is no problem. The servlet receives all information. Now I must also send 5 files which must be stored on the server. I have thus to add in my jsp 5 file fields.
My question :
Is it possible to integrate the FileUpload package for uploader my files without anything to change in my code (by using of a bean to exchange the data between my jsp and my servlet). ??
In other words, it is possible to use my bean to also transport files. ??
Tank u for u help

Yes it is possible..
download cos.jar from www.oreily.com for file upload..
it will read dat from the form as two parts ..
parameter part and file part..
and you can implement it throgh a servlet easily..
for more follow oreily JSP/servlets Cookbook

JSP/Servlets & XML - suggestion needed

Hi everyone,
I don't have any coding issues, I'm really just looking for some help on deciding how to go with a project I want to make. First off, I wrote a Java library that builds messages in a special format. I wanted to come up with a pretty frontend for it, so I decided I'd try my hand at a webapp since I've been interested in them for a while. So far my web app consists of jsps, servlets and my library.
At this point I'd like to add the ability for the webapp to store created messages in an XML file (read / write). The XML library I want to use is JAXB. I have it setup to read/write my XML file fine in a test servlet, however I'd like to implement this in a kind of "best practice" approach. So I'm looking for suggestions on how I should do this.
A few of my ideas:
1) Use a jsp page to call a "MessagesBean" which retrieves my data from my xml file. I could then format this nicely in the jsp page. The problem with this however is that I can't find any way to open a file relative to the webapp from within a Bean. ie. when I try to open "messages.xml", I can see from tomcat errors that it attempts to open it in tomcats bin folder (or if i run from within eclipse, eclipses bin folder). I know I could get around this by using an absolute path but I want this to be portable. Any suggestions?
2) To solve the above problem I found "getServletContext().getRealPath("")" in the Servlet API. Using this method I'm able to open my XML file relative to my webapp. The only issue I have here is that I'm now using a servlet to display the page, making it harder for me to format the output.
I'm very new to JSP/Servlets/etc so I really don't know how I should be doing this. I'm just trying to make sure I don't start out on the wrong foot. Can someone please give some suggestions on what I could do?
Cheers.

I suggested not putting business logic in the servlet, but instead instansiating a business logic object in the servlet and calling one of its functions to do the work.
There is nothing wrong with putting the business logic in the servlet on first try. Just later on, you might want to refactor the code to more conform to the above.
In your code, you mentioned that the MessagesBean in the JSP page doesnt seem to call the constructor. The <useBean> tag first looks to
see if the object is in request scope. If it is, it uses it (doesnt call constructor). If its not, it creates its own (calls constructor). You should always
have it in request scope ready for useBean to use.
I think this line:
<jsp:useBean id="messages" class="my.package.MessagesBean" />
should be changed to something like:
<jsp:useBean id="messages" class="my.package.MessagesBean" scope="request" />
The MessagesBean should only have get/set methods to get data out of its object (its a very simple object that holds data). None of its functions
should perform business logic such as hitting the database.
Therefore these items in your JSP page should be in the servlet or business logic:
messages.setPath( getServletContext().getRealPath("") ); // Pass in relative PATH
messages.processXML(); // Process XML file
While this should be in your JSP:
java.util.List<TEXT> TextFiles = messages.getTEXTFiles(); // Return a List of TEXT objects
Question: The JSP calls my Bean "MessagesBean". It then passes in the current relative path. This seems fairly hackish to me, is there a better way to give the relative path to my bean?
Answer: Hard code the relative path to the JSP page in the servlet or business logic. There is no need for the JSP page to pass its path back to the servlet or business logic. Your servlet
'knows' the path to all the JSP pages it needs to dispatch to.
The best way to learn MVC is to continually refactor your code until it looks more and more like MVC (separation of concerns).

Can somebody explain to me how JSP, servlets, ASP work within Sun's server

Ok, I'm only beginning to get a grip of how all this works. And I have a lot of questions and confusion.
1.) The server that comes with J2EE, what is that server? Is it an app server that runs only servlets and JSP, with some Web server stuff so it can output some info? Is it a stripped down version of TomCat? I am having a lot of trouble with the J2EE server (the one that comes with the SDK), and that is why I'm asking, maybe I don't need it. But I really want to learn JSP's, JScripts, and Beans. How else can I go about doing that, other than all out Tomcat.
2.) Also can I run Servlets on Microsft's IIS on a Windows 2000 machine? Do I need a special API to run servlets, or JSPs?
So how I see it, and again, I am a newbie at this. Machines that host a website, above all needs a web server. let's say most people use Apache, and they want to run it in Linux, becuase they want to be hackers. So then do they also run Tomcat, or IIS, or Coldfusion, or a million other servers in tandem on the same machine, so that they can handle ASP, JSPs, servlets, .cmf, etc.? or do they separate the app server from the webserver and then do some sort of linking? if somebody can direct me to how all this stuff works, I would greatly greatly appreciate it.

Sounds like you need to read the J2EE spec as well as
the servlet and JSP specs. It helps to glance through
sections you are interested in.
Ok, I'm only beginning to get a grip of how all this
works. And I have a lot of questions and confusion.
I think for a newbie, deploying your jsp's and servlets
to a J2EE compliant app server can be quite a headache.
You might want to concentrate on tomcat, which does servlet
and jsp.
Some app servers provide a http connector for most common web servers.
I think tomcat has a IIS connector. In this case IIS would serve static html as well as its own stuff, other things like servlets and jsp go to tomcat. I am unsure about this as I mostly use tomcat in standalone mode. You can run tomcat on windows, as it is written in java.
>
2.) Also can I run Servlets on Microsft's IIS on a
Windows 2000 machine? Do I need a special API to run
servlets, or JSPs?

Change Drop Down from Other JSP/Servlet/Bean

I am wanting to have a select box populate from a database query based on the information pulled from another select box as the user chooses it (ie a user chooses a state and the city choices populate or something like that). I am using JSP, Servlets and Beans. Seems that I need to us JSF, but I was wondering if there is another way or better way.
Thanks for the thoughts.

user12081556 wrote:
I meant to put in my question above, aren't jsf tags just imbedded in some jsp/html code?Not jsp code no. I don't know whether it's possible to use jsf and jsp together, but I wouldn't try.
While JSP has evolved over time from Html and Java code mixed together to standard tags responsible mostly for displaying the data, it's still an old "hack" that compiles jsp pages into servlets.
JSF at least alleviates some of those problems and works nicely with proper xhtml formatted views too (and there's facelets etc. etc. etc.).
Granted, if you're shown some jsp tags and jsf tags, you might not appreciate the difference in the technologies.

Menu item in Jsp/Servlet

Hi experts, when you're using Jsp/Servlet to implement the front-end web application, what options do you have for implementing some menu dropdown?
Is awt or swing can be used for that purpose?
How would you go about the layout management issue?
Thanks, and your reponse is appreciated

I guess You are looking for a solution in JSP/Servlets. Here is my program that might be help ful to you. This program will bring a drop down list that fetches the values from the database.
<table cellpadding=4 cellspacing=2 border=0 align=center>
<TR>
<TD><B>choose Code</B></TD>
<TD valign=top>

<% String userId =(String) session.getValue("userName"); %>
<%
Connection con = null;
Statement stmt = null;
ResultSet rs = null;
String uId;
String returnString="";
String null_value="";
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
con = DriverManager.getConnection("jdbc:oracle:thin:@serverName:1521:localHost", "scott", "tiger");
if (con == null) {
System.out.println("Connection not found");
stmt = con.createStatement();
con.setAutoCommit(false);
String sql= "select code from example_list where user_id='"+userId+"'";
rs= stmt.executeQuery(sql);
%>
<select name="alcList">
<%String aString;
rs= stmt.executeQuery(sql);
while (rs.next()) {
%>
<option value="<%= aString = rs.getString("code") %>">
<%= aString %></option> <%}%></select><%
con.commit();
//returnString= true;
} catch(SQLException sqlex) {
sqlex.printStackTrace();
//return returnString;
} catch(Exception ex) {
ex.printStackTrace();
} finally {
stmt.close();
con.close();
stmt = null;
rs = null;
con = null;
%></TD>
<TD align=center>
<INPUT TYPE=submit SIZE=30 VALUE="Submit"></TD>
</TR>
</Table>
</FORM>
</BODY>
</HTML>if this doesn't answer your problem, Please post your question exactly. May be I can help you out.
Good Luck.
-Sreekanth varidhireddy

JSP.Servlets ....

I am working on a application where I have JVM on Power PC hardware with Linux as OS. I have also configured Apache and Tomcat and everything is running fine. I can execute example servlets as well jsp pages.
My objective is to have java lib or jsp servlet (something) which will read /write data from Power PC and then pass it on to Host (Windows Application as well the web application
Question: how does my Host app written in VB NET or C# will retrieve this data form Power PC? The reason I want this way as i do not want to write Power PC data read/write code twice , one for website which will run on my Power PC and then second host applciation running on windows.
I hope I am making my point clear., any help or suggestion appriciated
Thanks
AGDT.

I am working on a application where I have JVM on
Power PC hardware with Linux as OS. I have also
configured Apache and Tomcat and everything is
running fine. I can execute example servlets as well
jsp pages.Very good.
My objective is to have java lib or jsp servlet
(something) which will read /write data from Power PC
and then pass it on to Host (Windows Application as
well the web applicationJava JVM running on Power PC or Windows can read or write data for that OS without a problem.
Web apps accept HTTP requests. HTTP protocol is the same for both Windows and PowerPC. What does the web app have to do with this?
Question: how does my Host app written in VB NET or
C# will retrieve this data form Power PC? Now I'm confused: Which is the host, which is the client, and where are the servlets and JSPs in all this mess?
The reason
I want this way as i do not want to write Power PC
data read/write code twice , one for website which
will run on my Power PC and then second host
applciation running on windows.What is the Windows host? Is it also an HTTP listener that you want the servlet to connect to and send data via HTTP?
I hope I am making my point clear., any help or
suggestion appriciated
Thanks
AGDT.Clear as mud to me. Perhaps you can explain it a little better, or someone else smarter than me will see what you're driving at.
%

Programmatically Registering a JSP/Servlet Portlet

???Programmatically Registering a JSP/Servlet Portlet???
OK, I have read all the literature on how to register a JSP/Servlet Portlet and have not seen any info on how to register a JSP/Servlet Portlet programmatically.
I know for sure that you can register a PL/SQL Portlet programmatically via a couple of SQL and PL/SQL scripts that were given in the PL/SQL PDK examples.
Bottom line, I want a way to register a new JSP/Servlet Portlet with ZERO GUI/User interface.
My questions are:
Is it possible to register a JSP/Servlet Portlet programmatically?????
If it is possible to register a JSP/Servlet Portlet programmatically, were is the info on it or can you give me some examples of it????
THANKS MUCH!!!
null

For a faster response, you may want to ask this question on the Portal Developer's Kit (PDK) Forum.

Different Classloader for JSP, Servlets?

Hi!
          Does the WL5-JSP-servlet use an other classloader then the other
          servlets??
          I've previous posted an article with the subject "JSP - Servlet - Static
          Code in Classes".
          I will try to describe my problem better:
          At server startup I pass information to my startup servlet, for example
          the user and pw for our connection pool. The startup servlet instanciates
          the class Global which creates a db-pool with the user and pw getting
          from
          the startup-servlet.
          startup-servlet {
          public void init(ServletConfig config)
          Global.init("user","pw");
          The class Global looks like this:
          class Global {
          static {
          // register jdbc driver
          // store file informations
          static public init(string, string) {
          // init the connection pool with user and pw
          static public getConnection() {
          // returns connection from pool
          All our other servlets then just use the methode Global.getConnection()
          and other methods from the class Global.
          All servlets works perfect and can access the db-pool.
          When a jsp-file is called which also uses the methode
          Global.getConnection(), a new Instance of the class Global will be made.
          In order to init all values again, I would have to call the
          Global.init(user, pw) methode again.
          So my question is: Why does the jsp file causes a new instance of the
          class Global?
          Does the WL5-JSP-servlet use an other classloader then the other
          servlets??


I am seeing the problem is sp3. I can't use sp4 becuase form based
          authentication, FBA, was broken. I can only hope that FBA will be
          re-fixed in sp5.
          Kumar Allamraju wrote:
          >
          > If you are seeing this problem in SP4, yes this is a regression in SP4 &
          > SP5. We are already aware of this
          > problem. SP5 will be out in a week or so. But this fix won't be available
          > in SP5. Follow-up with
          > support.
          >
          > --
          > Kumar
          >
          > "Bryon G. Rigg" wrote:
          >
          > > I have an application which has a servlet that controls page navigation
          > > via an xml file. The servlet class is located beneath the
          > > WEB-INF/classes as is the xml file. When I have weblogic pointing to
          > > the app directory, my servlet finds the xml file, using the
          > > Class.getResourceAsStream() method, without a hitch. But when I
          > > package everything up into a war file, and point weblogic at the war
          > > file instead, the servlet can not locate the xml file.
          > >
          > > What gives? Is there some kind of brain-dead classloader being used
          > > for war files versus a normal classloader used for directories? Any
          > > workarounds? And when will sp5 be released? I have been hearing a
          > > week or two for weeks.
          [bryon.vcf]

General JSP-Servlet question

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