JSP, Bean, or Servlet?

I've found that alot of the time, the systems I'm trying to design can use all of these to accomplish the same task. What's a good indicator of whether or not I should be using one technology over another?
For example, most recently, I designed an html form that is used to create registration html forms for clients. I can send the data in my form to another jsp page, a servlet, or a bean. ALL THREE can accept the date and use BufferedWriter to create and write to the registration form. Why would I want to use one over the other?
Any help here would be greatly appreciated. I am seriously lacking in proper system design knowledge.

If you want to use the data all through the user session, posting data to a JSP or a Servlet may require either URL rewriting or using hidden elements to preserve the state.
Its a better idea to store the data in a ValueObject (a simple java bean with get and set for all the properties).
You may want to refer to J2EE Patterns to find out more about the patterns you can use to design good server side application.

Similar Messages

Problem with JSP and Java Servlet Web Application....

Hi every body....
I av developed a web based application with java (jsp and Java Servlets)....
that was working fine on Lane and Local Host....
But when i upload on internet with unix package my servlets and Java Beans are not working .....
also not access database which i developed on My Sql....
M using cpanel support on web server
Plz gave me solution...
Thanx looking forward Adnan

You need to elaborate "not working" in developer's perspective instead of in user's perspective.

Prob with running jsp Bean

Hi,
I am trying to run a bean through a jsp but its giving error at useBean tag of jsp:
The error is :
HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException: /Quadratic.jsp(7,0) The value for the useBean class attribute com.brainysoftware.Quadratic is invalid.
     org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:39)
     org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:409)
     org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:150)
     org.apache.jasper.compiler.Generator$GenerateVisitor.visit(Generator.java:1227)
     org.apache.jasper.compiler.Node$UseBean.accept(Node.java:1116)
     org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2163)
     org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2213)
     org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2219)
     org.apache.jasper.compiler.Node$Root.accept(Node.java:456)
     org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2163)
     org.apache.jasper.compiler.Generator.generate(Generator.java:3272)
     org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:244)
     org.apache.jasper.compiler.Compiler.compile(Compiler.java:470)
     org.apache.jasper.compiler.Compiler.compile(Compiler.java:451)
     org.apache.jasper.compiler.Compiler.compile(Compiler.java:439)
     org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:511)
     org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:295)
     org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
     org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
My jsp is:
<HTML>
<HEAD>
<TITLE> JSP BEAN Quadratic Example </TITLE>
</HEAD>
<BODY>
<%@ page language="java" %>
<jsp:useBean id="quadratic" scope="session" class="com.brainysoftware.Quadratic" />
<jsp:setProperty name="quadratic" property="ia" param="a" />
<jsp:setProperty name="quadratic" property="ib" param="b" />
<jsp:setProperty name="quadratic" property="ic" param="c" />
X1= <%= quad.getDx1( ) %>
X2= <%= quad.getDx2( ) %>
End of program
</BODY>
</HTML>my bean is:
package com.brainysoftware;
import java.io.*;
class Quadratic{
int ia;
int ib;
int ic;
String dx1;
String dx2;
public int getIa( ) {
return ia;
public void setIa( int ii) {
ia=ii;
public int getIb( ) {
return ib;
public void setIb(int ii) {
ib=ii;
public int getIc( ) {
return ic;
public void setIc(int ii) {
ic=ii;
public String getDx1( ) {
double detA;
double result;
detA= ib*ib -4*ia*ic;
if(detA<0.0)
return "Real Roots not possible";
else {
result= -ib - Math.sqrt(detA/(2 * ia));
Double Dresult=new Double (result);
return Dresult.toString( );
public String getDx2( ) {
double detA;
double result;
detA= ib*ib -4*ia*ic;
if(detA<0.0)
return "Real Roots not possible";
else {
result= -ib + Math.sqrt(detA/(2 * ia));
Double Dresult=new Double (result);
return Dresult.toString( );
my directory structure is given below:
C:\tomcat-5.0.28\jakarta-tomcat-5.0.28\webapps\jsp-examples\WEB-INF\classes\com\
brainysoftware>dir
Volume in drive C has no label.
Volume Serial Number is 4C50-9542
Directory of C:\tomcat-5.0.28\jakarta-tomcat-5.0.28\webapps\jsp-examples\WEB-IN
F\classes\com\brainysoftware
05/22/2005 11:15 PM <DIR> .
05/22/2005 11:15 PM <DIR> ..
05/22/2005 11:18 PM 134 CalculatorBean.java
05/23/2005 12:12 AM 216 Counter.java
05/24/2005 10:48 PM 358 SimpleJavaBean.java
06/14/2005 11:16 PM 1,205 Calculator.java
06/14/2005 11:16 PM 1,323 Calculator.class
06/16/2005 06:44 PM 534 CalculatorBean2.java
06/17/2005 08:53 AM 703 CalculatorBean2.class
06/16/2005 07:00 PM 352 CalculatorBean2.html
06/17/2005 08:51 AM 588 CalculatorBean2.jsp
06/17/2005 04:29 PM 97 UploadBean.java
06/17/2005 04:43 PM 527 FileUploadBean.java
06/17/2005 04:43 PM 834 FileUploadBean.class
06/18/2005 12:21 PM 863 Quadratic.java
06/18/2005 12:21 PM 1,093 Quadratic.class
14 File(s) 8,827 bytes
2 Dir(s) 8,615,821,312 bytes free
C:\tomcat-5.0.28\jakarta-tomcat-5.0.28\webapps\jsp-examples\WEB-INF\classes\com\
brainysoftware>
The above clearly shows the presence of Bean in the reqd directory but still I am getting an error. Can somebody help me:
Zulfi.

class QuadraticThe class is not public. It is only visible to other classes in the same package as itself, so the servlet (JSP) trying to instantiate and reference it can't see it.
Make it public.

Jsp beans problem

hi all i have some trouble ...
i`m making a register form in jsp and i want to put the data into bean and then retrieve the data in a servlet
in the jsp i have:
<jsp:useBean id="data" class="DataBean">
<jsp:setProperty name="data" property="*"/>
</jsp:useBean>
<form method=post action="/SubmitServlet">
<input type=text name="message">
<input type=submit value="submit">
</form>
in the bean i have:
private String message = null;
public String getMessage() {
return message;
public void setMessage(String string) {
message = string;
and in the servlet:
public void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
HttpSession session = req.getSession();
     DataBean adr = (DataBean)session.getAttribute("data");
     if (adr==null) {
          System.out.println("ada");
     else {
     System.out.println(adr.getMessage());
.... and the server prints me the null string ... so the bean is not updated when i`m submiting the information from the jsp to the servlet ....
how could i make it right?

Oh, I see, when you said 'the Servlet prints the null string', you meant it gets to this line:
System.out.println(adr.getMessage());
and prints "null", right?
Well, that is because you never set the message. The way your JSP works:
1) Create a DataBean and store it in session (are there paramameters? no, so don't call any set methods)
2) Display a Form.
Then when the User presses the submit button, you have an action set to the Servlet /SubmitServlet, not back to the JSP. So, the Servlet has to handle the parameters passed from the form, not JSP. The JSP is done after it displays the page.
public void doPost(...) ...
HttpSession session = req.getSession();
DataBean adr = (DataBean)session.getAttribute("data");
if (adr==null) {
    adr = new DataBean();
    session.setAttribute("data", adr);
String message = req.getParameter("message");
adr.setMessage(message);
System.out.println("The Message Is: "+message);
//Maybe do a forward?? or some display??
}If you want the JSP to handle the parameters sent by the form, then you will have to make the form's action set to the same address, not to the servlet (see my message in the first reply about how to make sure the setProperty gets called...)

How to pass a object of JSP to a servlet called from JSP

Hi,
I am trying to display an image in the JSP through html image tag. I am using Struts Action class to get the image data from the database through a Session EJB. I am getting a byte array for the image retrieved from the database.
To display the image I need to call a servlet from the JSP from the image tag like this.
<html:img src="imageservlet" border="0"/>
But I need to send the image byte [] array data which is available with the JSP to the servlet to build image. I have a bean object with the JSP which holds the image byte []. The servlet should receive the bean object and will use the byte [] and build the image to be displayed.
My query here is how to send this bean object to the servlet which is getting called from the JSP as shown above.
Thanks in advance.

Hi,
Thanks for your response. I knew it is possible with session objects. But I want to perform this operation with out using session objects. Is there a way to accomplish this with out using Session objects.
Please help.
Thanks

Create session scoped bean in servlet?

I am working on a log in porgram for a jsp page using servlet.
I need to create a bean in that servlet after user enter correct username and password, and the bean must have scope of session.
How do I do this?
How do I control the scope of variables in a servlet?
thank you

come on people! i just answered this 2 minutes ago! search the forums first! or a servlet book.
servlet...
Bean bean = new Bean();
bean.setValue("value");
request.getSession().setAttribute("bean", bean);
jsp...
<jsp:useBean id="bean" class="Bean" scope="session" />
<%= bean.getValue() %>
OR
<%
Bean bean = (Bean)session.getAttribute("bean");
%>

Using java bean in servlet

Hi,
I have a problem in getting the values from simple bean to servlet. The project has one html form. When the user click on the submit button one jsp will be invoked which calls a bean program to validate the user data for required fields. Based on the result, jsp program forward the control to a servlet which stores the data in a database. Otherwise another jsp is called to inform the user to fill in the required data.
My problem is how to send the data from bean to servlet?
The snippet of jsp that calls bean is like this :
<%!
%>
<jsp:useBean id="formHandler" class = "subFormBean" scope="request">
<jsp:setProperty name="formHandler" property="*"/>
</jsp:useBean>
<%
if (formHandler.validate()) {
%>
<jsp:forward page="subscriberRegistration"/>
<%
} else {
%>
<jsp:forward page="retry.jsp"/>
<%
%>
And the snippet of the bean is like this :
public boolean validate() {
boolean bool=true;
if (subname.equals("")) {
errors.put("subname","Please enter your Name");
subname="";
bool=false;
public subFormBean() {
subname="";
public String getSubName() {
return subname;
public void setSubName(String sname) {
subname =sname;
The servlet which is to receive the data is like this :
public class subscriberRegistration extends HttpServlet{
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
subFormBean sfb = new subFormBean();
sfb.setSubName(subname);
But I'm getiing error while trying to compile the servelet saying that no variables found - sfb, subname etc.
Please let me know how to invoke the bean from servlet. I want to use servlet to instead of jsp to insert records into database. How can i do this? Please help me. Thanks in advance.

Hi Tolls,
Sorry, I'll give a bigger snippet of the prog.code below :
public class subscriberRegistration extends HttpServlet{
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
subFormBean sfb = new subFormBean();
sfb.setSubName(subname);
sfb.setSubAddress(subaddress);
sfb.setSubCity(subcity);
sfb.setSubState(substate);
sfb.setSubCntry(subcntry);
sfb.setSubPin(subpin);
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException{
response.setContentType("text/html");
PrintWriter pw = response.getWriter();
Class.forName("oracle.jdbc.driver.OracleDriver");
connection = DriverManager.getConnection(connectionURL,"scott","tiger");
stmt = connection.createStatement();
rs = stmt.executeQuery("SELECT subid_seq.NEXTVAL FROM DUAL");
while(rs.next()) {
String subno = rs.getString("NEXTVAL");
PreparedStatement pst = connection.prepareStatement("insert into eps_subscriber(eps_subno, eps_subname, eps_subaddress, eps_subcity, eps_substate, eps_subcntry, eps_subpin, eps_subphno, eps_subemailid, eps_subuserid, eps_subpwd) values(?,?,?,?,?,?,?,?,?,?,?)");
pst.setString(1,subno);
pst.setString(2,sfb.subname);
pst.setString(3,sfb.subaddress);
pst.setString(4,sfb.subcity);
pst.setString(5,sfb.substate);
pst.setString(6,sfb.subcntry);
pst.setString(7,sfb.subpin);
I'm validating the form data in beans program. Servlet is used to insert records into the database. So, i'm trying to capture data from the bean. How to capture the data from the bean to servlet? Or should I get it from the form fields directly? The servlet worked well when data was captured directly from html form fields. Please help me to fix this. Thanks in advance.

NEWBIE SUPER EASY JSP / BEAN

With about half a dozen books sitting around my desk, I can't get a REAL basic jsp to work. I FINALLY got tomcat to NOT give run time errors, however the web page simply outputs "This is output:" I know I am an idiot, but this JSP / bean stuff is upsetting. Any help on the following code would be great.
basic.jsp is as follows:
<jsp:useBean id="myBean" class="basic.basicbean" scope="session"/>
<html>
<head>
<title>
A Simple JSP
</title>
</head>
<body>
<%
myBean.setBasicName("Michelle");
%>
This is output: <% myBean.getBasicName();%>
</body>
</html>
basicbean.java is as follows:
package basic;
import java.beans.*;
public class basicbean {
private String BasicName=null;
/** Creates new basicbean */
public basicbean() {}
public String getBasicName() {
return this.BasicName;
public void setBasicName(String value) {
this.BasicName = value;
Made the .java into the class put it in the basic directory under the classes/basic directory of the WEB-INF. The JSP page loads, but only output is: "This is output:" I am using Tomcat as the JSP server. "Core JSP" "Core Servlets and JavaServer Pages" "Advanced JavaServer Pages" "JSP, Servlets, and MySQL", and "Java Server Pages for Dummies" and I still can't get it. Thanks for helping out an idiot.
-Jim

You are very close; just a small error in the line:
This is output: <% myBean.getBasicName();%>
The problem is your just simply calling the method and tossing the return value. You have three ways of outputing the bean property:
This is output: <% out.print(myBean.getBasicName();%>
or
This is output: <%=myBean.getBasicName()%>
or
This is output: <jsp:getProperty name="myBean" property="BasicName" />
If you use the <jsp:getProperty> approach, then you must have a <jsp:useBean> somewhere above the getProperty tag.
- Chris

Send data from bean to servlet and get results back to bean

Hi,
I'm new to this helpful forum and, as long as I'm practicing with JFS and Java Beans and Servlets, I really need some help about the following crappy issue.
I made a JSP login page called "LoginPage.jsp" (using "Visual Web JSF Page" tool in NetBeans 6.0), and the action associated to the "Login" button pression is defined in the associated Java Bean "LoginPage.java":
Code from "LoginPage.jsp":
<webuijsf:button actionExpression="#{LoginPage.loginButton_action}" binding="#{LoginPage.loginButton}" id="loginButton" primary="true" style="height: 24px; left: 383px; top: 192px; position: absolute; width: 96px" text="Login"/>
Code from "LoginPage.java":
public String loginButton_action()
    if (usernameField.equals("guest") && passwordField.equals("guest")) // this control should be done by a servlet, not here!
        return "loginOK"; // this is the outcome for faces-config.xml that will lead to a "Welcome.jsp" page
    else
        return "loginERROR"; // this is the outcome for faces-config.xml that will lead to a "Error.jsp" page
...Now, the problem is that the username and password control should not be done by the bean itself, but by a servlet (call it "LoginServlet.java").
In a few words, what I mean is that once the user writes username and password and presses the "Login" button, the called "loginButton_action()" forwards all the needed data to the servlet "LoginServlet.java", the servlet does the complete checks about login validity then prepares the result (it could be a string reporting "OK" or whatever else) and send it back to the bean "LoginPage.java", so that the flow can continue.
My problem is that I absolutely don't know how to make a bean and a servlet communicate in both ways and respectively exchange data.
Thanks in advance for any help, it will really be appreciated.

Google for passing values in request and session.

Redundant information in JSP bean action

Class Person:
public class Person{
private String name;
public void setName(String p){
name=p;
public String getName(){
return name;
}Code in servlet:
public void doPost(HTTPServletRequest request, HTTPServletResponse response) throws IOException,ServletException{
foo.Person p= new foo.Person();
p.setName("New Guy");
request.setAttribute("person",p);
RequestDispatcher view = request.getRequestDispatcher("result.jsp");
view.forward(request,response);
}Code in JSP:
<jsp:useBean id="person" class="foo.Person" scope="request">This jsp:useBean tag really is confusing. Why does it need to declare the class="foo.Person"? Why does the JSP need to know that "person" instance is derived from class foo.Person ? (I wonder if I changed this to foo.person --> not Person will result in error). Doesn't the statement request.setAttribute("person",p) from the servlet give enough info already to the JSP? thanks

The "person" in your servlet has nothing to do with your "person" in your JSP bean tag.

Retrieve values from a table of a JSP page in Servlet.

Hello all,
I am new in JSP servlet world, I want to create a grid on JSP page using Servlet.
Suppose i have some records in a JSP page and This JSP page will display these records in a tabular form. And, on a button click that table data should be
accessible in servlet,
Now, How can i traverse among all the rows of that table of JSP page in servlet. or How can i retrieve a specific cell record of that table of JSP page in servlet.
Can anyone please answer this.
Thank you and regards.

Hi,
Create in your HTML form inputs with the same name i.e.:
<input name="a[]" value="2" >
<input name="a[]" value="9" >
In your jsp page use :
String Values[] = request.getParameterValues("a[]") ;
This will give you a string array of two elements.
for (int x = 0; x < Values.length; x++)
System.out.println(Values[x]) ;
}Will print :
2
9
Hope this helps.
Bill Moo

Urgent....How can i redirect to my jsp page from servlet in init() method..

How can i redirect to my jsp page from servlet in init() method..Becoz that servlet is calling while server startsup..so im writing some piece of code in init() method..after that i want to redirect to some jsp page ...is it possible?
using RequestDispatcher..its not possible..becoz
RequestDispatcher rd = sc.getRequestDispatcher("goto.jsp");
rd.foward(req,res);
Here the request and response are null objects..
So mi question can frame as how can i get request/response in servlet's init method()..

Hi guys
did any one get a solution for this issue. calling a jsp in the startup of the servlet, i mean in the startup servlet. I do have a same req like i need to call a JSP which does some data reterival and calculations and i am putting the results in the cache. so in the jsp there in no output of HTML. when i use the URLConnection i am getting a error as below.
java.net.SocketException: Unexpected end of file from server
at sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:707)
at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:612)
at sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:705)
at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:612)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLCon
nection.java:519)
at com.toysrus.fns.alphablox.Startup.callJSP(Unknown Source)
at com.toysrus.fns.alphablox.Startup.init(Unknown Source)
at org.apache.tomcat.core.ServletWrapper.doInit(ServletWrapper.java:317)
so plz do let me know how to call a jsp in the start up of a servlet.
Thanks
Vidya

Accessing String assigned in a JSP from a Servlet?

Hello all, I was wondering if there is a way to access a String object that was assigned by an HttpSession object in a JSP from a Servlet. What happens is, in my application a user logs in, an HttpSession object is instantiated and all of the user credentials are assigned within a JSP like:
HttpSession httpSession = request.getSession( false );
String userName = httpSession.getAttribute("userName);
...{code}
Next, I have a Servlet (which is really just a Proxy to a different server), that I need to log some information with, namely the userName String. Is there a way I can access that String without instantiating another HttpSession object? Because when the timeout occurs (or when the user clears his cache I have found), the HttpSession becomes invalidated (even if I use +HttpSession#getSession( true )+) and the +HttpSession#getAttribute+ call fails (userName is just null). So is this possible to do?
Thanks in advance!

dnbphysicist wrote:
I understand you cannot recover attributes from a dead session, this is why I wanted to be able to access a variable that is pulled from the Session immediately after login so I can still get to it even once the session is dead.
Normally a session doesn't go dead after login.
I imagine that by using application scope the app would confuse the userName with other users that are logged in?Certainly. It was just an example. But your data clearly belongs in the session, so just keep it in the session. If the session get invalidated while it should not get invalidated, then your problem truly lies somewhere else.
I am definitely not arguing you latter point either :) A lot of this code I inherited unfortunately from previous developers and we are in desperate need of a redesign.I wish you much luck with that.

Strange behavior with entity beans and servlets in a cluster

We have 2 WebLogic 4.5.1 servers in a cluster with none of the Service
          Packs installed. When a client uses the deployed entity beans or
          servlets they work every other time. The times they do not work nothing
          happens. No exceptions, no responses to the client ( i.e. HTTP 404s ),
          nothing. I suspect something in the cluster setup since we do not have
          these same problems on non-clustered entity beans or servlets. We have
          made sure all the entity beans have the Shared Database flag set on and
          added the delayUpdatesUntilEndOfTx false to the enviroment of the DD.
          That didn't fix the problem. Any ideas?
          Thanks in advance,
          Dallas Dempsey
          DEM - Houston, TX


Do you have log files?
          - Prasad
          Chris Dempsey wrote:
          > We have 2 WebLogic 4.5.1 servers in a cluster with none of the Service
          > Packs installed. When a client uses the deployed entity beans or
          > servlets they work every other time. The times they do not work nothing
          > happens. No exceptions, no responses to the client ( i.e. HTTP 404s ),
          > nothing. I suspect something in the cluster setup since we do not have
          > these same problems on non-clustered entity beans or servlets. We have
          > made sure all the entity beans have the Shared Database flag set on and
          > added the delayUpdatesUntilEndOfTx false to the enviroment of the DD.
          > That didn't fix the problem. Any ideas?
          >
          > Thanks in advance,
          > Dallas Dempsey
          > DEM - Houston, TX

Generating the JSP from the Servlet source file

Hi,
Does anyone out there know if there is any utility/class/program which will generate a JSP from the Servlet Source file (.java file) or indeed from the compiled Servlet file (.class file)
If its possible to decompile a .class file into a .java file, surely it must be possible to convert the .java souce file into the .jsp file that created it.
any comments would be appreciated
Richard

I am the author of the original JSP!
But I want to run a script on the generated Servlet source file,
changing its contents, and then generate the JSP that would have created the new Servlet source file.
but I need to know if theres anything that will reverse engineer a Servlet source into the generating JSP.
its a kind of of Jeopardy type thing!

JSP, Bean, or Servlet?

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