The use of javabean in a servlet

I used a javabean in (scope=application) a jsp, but now I want to use that bean in my servlet, can anybody show me how?

why not share with others ??
please write out

Similar Messages

How to use a javaBean in a servlet without FORMS...

Hi,
I would like to use a javaBean in a Servlet.
I know how you can do this with the code
HttpSession session = request.getSession();
in your servlet.
However, by using this code you have to call the servlet by a FORM. Is it possible to call the servlet (which calls the javaBean) in your JSP file without a FORM?
Greetings
Tigi

Thanks Anthony,
I'm working with Tigi on the same project and now I can tell you that the problem is solved.
request.getRequestDisptacher("/myServlet");hehe, you switched the 't' and the 'a'
<%@ include file="/myServlet" %>this is the one we use :)
But what is the difference between the first one and the last one? Now We are using the last one because that's the shortest :) not a pretty good reason huh :)
cheers,
Soep

Problem to connect to mysql from servlet using a javabean

Hi,
I'm new here and beginner on java to.
I have problem to connect to MySql database, by a connection javabean.
It's the following: a HTML page calls a servlet and this servlet imports the package connection javabean.
It has no problem when I establish the connection inside the servlet, with all its methods (public and private). But i want to separate the code connection from servlet.
Detail: there is no problem, using the javabean to connect to MS Access database.
I put "mysql-connector-java-3.1.12-bin.jar" file inside WEB-INF/lib application and common/lib directories.
I set the classpath:
SET CLASSPATH=%CATALINA_HOME%\COMMON\LIB\mysql-connector-java-3.1.12-bin.jar;%CLASSPATH%
I think that the servlet cannot create an instance of javabean, because passed by catch exception of the servlet init method.
But I don't know why.
Please Why?
Below there are the fragment of errors, servlet code e javabean code.
Thank you.
Zovao.
HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
java.lang.NullPointerException
at CadServletFileBeanConexArq.doPost(CadServletFileBeanConexArq.java:47)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:716)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:809)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:200)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:146)
Note: The line 47 is calling insertIntoDB javabean method.
========///////////////===============
// Here is the servlet CadServletFileBeanConexArq.java
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.sql.*;
import conJdbc.*;
public class CadServletFileBeanConexArq extends HttpServlet {
public ConexPed connect = null;
private String driver = "com.mysql.jdbc.Driver";
private String URL = "jdbc:mysql://localhost:3306/cadastro";
public void init( ServletConfig config )
throws ServletException
super.init( config );
try
connect = new ConexPed(driver, URL, "monty", "some_pass");
catch ( Exception e )
e.printStackTrace();
connect = null;
public void doPost( HttpServletRequest req,
HttpServletResponse res )
throws ServletException
boolean success = true;
String email, nome, sobrenome, produto, valor;
email = req.getParameter( "Email" );
nome = req.getParameter( "Nome" );
sobrenome = req.getParameter( "Sobrenome" );
produto = req.getParameter( "Produto" );
valor = req.getParameter( "Valor" );
res.setContentType( "text/html" );
if ( email.length() > 0 && nome.length() > 0 && sobrenome.length() > 0 && valor.length() > 0 )
/* inserting data */
success = connect.insertIntoDB(
"'" + email + "','" + nome + "','" + sobrenome + "','" + produto + "'", Double.parseDouble(valor) );
//closing connection
public void destroy()
connect.fecharConexao();
=============///////////////============
Here is the JavaBean.
package conJdbc;
import java.sql.*;
public class ConexPed
public Connection connection;
public Statement statement;
public ConexPed (String driver, String urlServidor, String user, String password)
try
Class.forName(driver);
connection = DriverManager.getConnection(urlServidor,user,password);
catch (ClassNotFoundException ex)
System.out.println("N�o foi poss�vel encontrar a classe do Driver: " + driver);
catch (SQLException ex)
System.out.println("N�o foi poss�vel conectar ao servidor");
try
statement = connection.createStatement();
catch (SQLException ex)
System.out.println("N�o foi poss�vel criar a statement");
*Inserting data to database
public synchronized boolean insertIntoDB( String stringtoinsert, double valor)
try
statement.executeUpdate( "INSERT INTO pedido values (" + stringtoinsert + " , " + valor + ");" );
catch ( Exception e ) {
System.err.println(
"ERROR: Problemas ao adicionar nova entrada" );
e.printStackTrace();
return false;
return true;
* Close statement.
public void fecharStatement()
try
statement.close();
catch (SQLException ex)
ex.printStackTrace();
* close database
public void fecharConexao()
try
connection.close();
catch (SQLException ex)
ex.printStackTrace();
}

Hi,
I'm new here and beginner on java to.
I have problem to connect to MySql database, by a connection javabean.
It's the following: a HTML page calls a servlet and this servlet imports the package connection javabean.
It has no problem when I establish the connection inside the servlet, with all its methods (public and private). But i want to separate the code connection from servlet.
Detail: there is no problem, using the javabean to connect to MS Access database.
I put "mysql-connector-java-3.1.12-bin.jar" file inside WEB-INF/lib application and common/lib directories.
I set the classpath:
SET CLASSPATH=%CATALINA_HOME%\COMMON\LIB\mysql-connector-java-3.1.12-bin.jar;%CLASSPATH%
I think that the servlet cannot create an instance of javabean, because passed by catch exception of the servlet init method.
But I don't know why.
Please Why?
Below there are the fragment of errors, servlet code e javabean code.
Thank you.
Zovao.
HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
java.lang.NullPointerException
at CadServletFileBeanConexArq.doPost(CadServletFileBeanConexArq.java:47)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:716)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:809)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:200)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:146)
Note: The line 47 is calling insertIntoDB javabean method.
========///////////////===============
// Here is the servlet CadServletFileBeanConexArq.java
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.sql.*;
import conJdbc.*;
public class CadServletFileBeanConexArq extends HttpServlet {
public ConexPed connect = null;
private String driver = "com.mysql.jdbc.Driver";
private String URL = "jdbc:mysql://localhost:3306/cadastro";
public void init( ServletConfig config )
throws ServletException
super.init( config );
try
connect = new ConexPed(driver, URL, "monty", "some_pass");
catch ( Exception e )
e.printStackTrace();
connect = null;
public void doPost( HttpServletRequest req,
HttpServletResponse res )
throws ServletException
boolean success = true;
String email, nome, sobrenome, produto, valor;
email = req.getParameter( "Email" );
nome = req.getParameter( "Nome" );
sobrenome = req.getParameter( "Sobrenome" );
produto = req.getParameter( "Produto" );
valor = req.getParameter( "Valor" );
res.setContentType( "text/html" );
if ( email.length() > 0 && nome.length() > 0 && sobrenome.length() > 0 && valor.length() > 0 )
/* inserting data */
success = connect.insertIntoDB(
"'" + email + "','" + nome + "','" + sobrenome + "','" + produto + "'", Double.parseDouble(valor) );
//closing connection
public void destroy()
connect.fecharConexao();
=============///////////////============
Here is the JavaBean.
package conJdbc;
import java.sql.*;
public class ConexPed
public Connection connection;
public Statement statement;
public ConexPed (String driver, String urlServidor, String user, String password)
try
Class.forName(driver);
connection = DriverManager.getConnection(urlServidor,user,password);
catch (ClassNotFoundException ex)
System.out.println("N�o foi poss�vel encontrar a classe do Driver: " + driver);
catch (SQLException ex)
System.out.println("N�o foi poss�vel conectar ao servidor");
try
statement = connection.createStatement();
catch (SQLException ex)
System.out.println("N�o foi poss�vel criar a statement");
*Inserting data to database
public synchronized boolean insertIntoDB( String stringtoinsert, double valor)
try
statement.executeUpdate( "INSERT INTO pedido values (" + stringtoinsert + " , " + valor + ");" );
catch ( Exception e ) {
System.err.println(
"ERROR: Problemas ao adicionar nova entrada" );
e.printStackTrace();
return false;
return true;
* Close statement.
public void fecharStatement()
try
statement.close();
catch (SQLException ex)
ex.printStackTrace();
* close database
public void fecharConexao()
try
connection.close();
catch (SQLException ex)
ex.printStackTrace();
}

How to get javabean data in Servlets.( JavaBean -- Servlet(Controller)

how to get javabean data in Servlets.
1) I am using name ,password in Jsp(View )
2) when I submit this Bean will be called and Setter methods will be called .
3) In ServletController (controller) I want to get data of javabean.
In this I have to do validation of user.
I want to pass the javabean obj as like -->
request.getAttribute("beanObj");
My intention is to get all the poperties in javabean by passing bean id
or beanobj ,
Is there any way to get all the data using bean id or beanObj.
Plz Reply,

Now in the Servlet we can get the same bean by this code:
PageContext pageContext = JspFactoryImpl.getDefaultFactory().getPageContext(this, request, response, null, true, 8192, true);
UserBean userbean = (UserBean)pageContext.getAttribute("userbean", PageContext.SESSION_SCOPE);
String userid = userbean.getUsername();
For this code to work it is needed to import 2 files:
import org.apache.jasper.runtime.JspFactoryImpl;
import javax.servlet.jsp.PageContext;
The JspFactoryImpl is in jasper-runtime.jar file provided in tomcat dir.It seems to me that you are exactly knowing what you are doing :-(
You can get a Bean stored in a Session by
request.getSession().getAttribute("userbean");
In the login.jsp page for example we have the code
<jsp:useBean id="userbean" scope="session"class="com.newproj.UserBean" />
<jsp:setProperty name="userbean" property="*" />the jsp:setProperty is not called when you click on the submit button
if fills the bean with the request values from the previous request.
andi

What is the use of bean?

I'm new to JSP.What is the use of bean? And how do we write it? Can I do the JSP which connect to database without using the bean?

You don't need JavaBeans when working with JSPs. For info on JavaBeans look here: http://developer.java.sun.com/developer/onlineTraining/Beans/beans02/
As a general rule of thumb it's not a very good idea to have JSPs connect directly to a database. I'd higly recommend you pickup "Java Servlet Programming" from O'Reilly, it covers Servlets, JSPs and how to tie them together.

How to use a JavaBean with request scope from one page to other page

Hi,
I want to use in one jsp file a javabean with scope of request for it, I use:
<jsp:useBean id="entry" class="jsps.SaleEntry" scope="request" />and after in that page I make operations with it using the jsp:setProperty and jsp:getProperty operations
My question is that if I want to get the result of that javabean in the following page, Have I to record the javabean doing : request.setAttribute(""objectId",id) and then in the following jsp page I can rescue the object doing: SaleEntry sE=(SaleEntry) request.getAttribute("objectId") ???
or in the contrary, only using jsp:setProperty the information is available to recover it in the following jsp doing : SaleEntry sE=(SaleEntry) request.getAttribute("objectId") because setProperty records the information without need of doing : request.setAttribute(""objectId",id). ????
Thanks with anticipation and sorry if it is a silly question but I am beginner in the use of JavaBeans

Thanks Anthony,
I'm working with Tigi on the same project and now I can tell you that the problem is solved.
request.getRequestDisptacher("/myServlet");hehe, you switched the 't' and the 'a'
<%@ include file="/myServlet" %>this is the one we use :)
But what is the difference between the first one and the last one? Now We are using the last one because that's the shortest :) not a pretty good reason huh :)
cheers,
Soep

How to get a CA certificate installed in the web trust db from java servlet

Hi all.
Hi, I have a web-app that requires a client certificate from a CA. The CA cert is in the trust db of the webserver. And I would like to get the CA certificate (X509Certificate) corresponding to the issuer of the current client certificate of the request. Is there an easy way of doing this from a java servlet?
I'm using Sun Java System Web Server 6.1
Thanks in advance.

Hi, thanks for your quick answer.
I have to check the client certificate revocation status using ocsp protocol. I'm cheking ogro project ocsp library (http://dev.globus.org/wiki/Incubator/OGRO) to check this status against my CA validator agency. In order to use this library in my servlet to check the status I need both the client cert and the issuer cert. So that is why I need to get the CA cert from my trust db.
There is another way, I have the cert as file (the same I used to import the CA cert in my trust db), and I get the cert from the file. With this cert and the cert from the client I do the ocsp request and it works. But I trying to avoid having the CA cert in a file and recover the cert from the trust db.
Thanks

How to use connection pool in jsp/servlet ?

I found I can "lookup" it in either java beans/servlets/JSP using JNDI. why?
what is the best practice to use it in a jsp/servlet web app considering JNDI lookuping expensive?
Thanks!
Bo
Edited by: BobXu on Nov 17, 2008 2:27 PM
Edited by: BobXu on Nov 17, 2008 2:32 PM

Huh?
You can lookup a JNDI resource from anywhere in java code you want to. As long as you have a repository set up to search on :-)
Of course whether that resource is available or not is a different matter. If you let the server set up the JNDI resource for you, then you can't run it standalone outside the server without something else setting the same thing up :-)
So its not so much a limitation of beans, but just the environment you run the code in.
Best practice? Don't write sql queries in JSP pages :-)
For the rest you might consider the DAO pattern. Or ignore SQL altogether and let hibernate do the work there for you.
Cheers,
evnafets

JAVA.LANG.NULLPOINTEREXCEPTION WHILE USING GETCLIENTINFO JAVABEAN IN FORM

We are using GetClientInfo JavaBean in Oracle 6i Form registered in Oracle Applications. Earlier, when we used Jinitiator, the Form used to open properly. Recently we started using Java Plug-in 1.6.0_12 (JRE version 1.6.0_12 Java HotSpot(TM) Client VM), we get following errors and then entire application closes.
java.lang.NullPointerException
     at oracle.forms.ui.VBean.isFocusTraversable(Unknown Source)
     at java.awt.Component.isFocusable(Unknown Source)
     at java.awt.Component.isRequestFocusAccepted(Unknown So

Get Client Information
http://www.oracle.com/technology/sample_code/products/forms/6idemos.html
java.lang.NullPointerException
     at oracle.forms.ui.VBean.isFocusTraversable(Unknown Source)
     at java.awt.Component.isFocusable(Unknown Source)
     at java.awt.Component.isRequestFocusAccepted(Unknown Source)
     at java.awt.Component.requestFocusHelper(Unknown Source)
     at java.awt.Component.requestFocusHelper(Unknown Source)
     at java.awt.Component.requestFocus(Unknown Source)
     at oracle.forms.handler.UICommon.updateFocus(Unknown Source)
     at oracle.forms.handler.UICommon.setFVP(Unknown Source)
     at oracle.forms.handler.UICommon.setFVP(Unknown Source)
     at oracle.forms.handler.UICommon.onUpdate(Unknown Source)
     at oracle.forms.handler.ComponentItem.onUpdate(Unknown Source)
     at oracle.forms.handler.JavaContainer.onUpdate(Unknown Source)
     at oracle.forms.handler.UICommon.onUpdate(Unknown Source)
     at oracle.forms.engine.Runform.onUpdateHandler(Unknown Source)
     at oracle.forms.engine.Runform.processMessage(Unknown Source)
     at oracle.forms.engine.Runform.processSet(Unknown Source)
     at oracle.forms.engine.Runform.onMessageReal(Unknown Source)
     at oracle.forms.engine.Runform.sendDeferredMessages(Unknown Source)
     at oracle.forms.engine.Runform.onMessage(Unknown Source)
     at oracle.forms.engine.Runform.sendInitialMessage(Unknown Source)
     at oracle.forms.engine.Runform.startRunform(Unknown Source)
     at oracle.forms.engine.Main.createRunform(Unknown Source)
     at oracle.forms.engine.Main.start(Unknown Source)
     at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)

Using a JavaBean in JSP

Hello,
I am very new at this, and I am doing a very simple tutorial to use a JavaBean in JSP. I have followed all the procedures from my tutorial, and I get the following error:
org.apache.jasper.JasperException: Can't find a method to write property 'make' of type 'java.lang.String' in a bean of type 'com.wrox.cars.CarBean'
I have the bean:
package com.wrox.cars;
import java.io.Serializable;
public class CarBean implements Serializable {
private String make = "Ford";
public CarBean(){
public String getMake(){
return make;
public void SetMake(String make)
this.make = make;
and the JSP:
<jsp:useBean id="myCar" class="com.wrox.cars.CarBean" />
I have a <jsp:getProperty name="myCar" property="make" /><br>
<jsp:setProperty name="myCar" property="make" value="Ferrari" />
Now I have a <jsp:getProperty name="myCar" property="make" /><br>
The only thing I am missing is this step, where I have been looking for these JAR files and can't find them
I have downloaded many JSTL libraries, and still can't find them/
- dom.jar
- jaxp-api.jar
- jdbc2_0-stdext.jar
- sax.jar
- xalan.jar
- xercesImpl.jar
I really appreciate any help.

Thanks a lot.
Although I should know that, it seems that the error was in the tutorial.
Thanks again,

Using additional jars in portal (jregex1.2_01.jar ) and use of javabeans

Hi
I want to use code that parses regular expressions with java and to that end I would like to use jregex1.2_01.jar (if there is a native jar file in oracle that does the same, that woule be good, but I could not find anything that refers to regex or jregex).
I tried to put that new jar file in two locations in the portal area under WEB-INF\lib, namely in:
C:\oracle\ora9ias\j2ee\OC4J_Portal\applications\portal\portal\WEB-INF\lib
where there are a lot of other jar files and also in:
C:\oracle\ora9ias\j2ee\OC4J_Portal\applications\jpdk\jpdk\WEB-INF\lib
However, when I try to compile my code, it fails on the import line:
import jregex.util.io.*;
(the line itself is correct)
Obviously the jregex1.2_01.jar file is not in my classpath, but when oracle was installed, it did not create a CLASSPATH environment variable, so I would not like to make one that may exclude others oracle jars that then are not listed in CLASSPATH.
I have two questions:
1. How does import additional jars into Oracle, so that they can be used by java programs, and are there any inherent dangers in doing that?
2. Where do I place my class file, if I want to use that class file as a javabean. The bean will be referred to by a jsp file which has been imported as a portlet. I assumed I would place my beans under
C:\oracle\ora9ias\j2ee\OC4J_Portal\applications\jpdk\jpdk\WEB-INF\lib
as my jsp files are residing close to that, namely in:
C:\oracle\ora9ias\j2ee\OC4J_Portal\applications\jpdk\jpdk\htdocs\myjsps
but I am not sure.
Can anyone help me with setting up additional jars so they can be used by java files (to be used as javabeans) and with the location and use of javabeans in Oracle Portal?
Any help will be greatly appreciated.
Thanks very much
Hugo

Hi Hugo,
When developing server-side applications, forget about the CLASSPATH environment variable. You must instead become familiar with how the server's classloading scheme operates.
From your post, it looks as though you already are familiar to some degree, because you have correctly identified one of the places to put extra jar files, namely WEB-INF/lib.
At first glance, I would have expected your import to work with the jar file located in WEB-INF/lib - have you made sure you bounced the server?
Also, make sure that any dependencies of jregex are also included in WEB-INF/lib.
Another thing to try is add an entry into ${OH}/j2ee/OC4J_Portal/config/application.xml which explicitly references the jregex jar file.
Regards,
Gareth
(PDK team)

JavaBean JSP to Servlet

Presuming this is an easy one.
I have created a JavaBean in a JSP page that submits a form to a Servlet, how do I send the JavaBean to the Servlet?
I know how to create a JavaBean in a Servlet and send it to a JSP page but not vise versa.

The bean you created in the JSP no longer exists when the returning form content hits the servlet, it's a new transaction.
So the first thing the servlet needs to do is to create a new instance of the bean and load data from the parameters into the corresponding bean attributes. There are library classes in Spring, Struts or apache commons to do this stuff, or you can simply do it yourself like:
MyDto dto = new Dto();
dto.setField1(request.getParameter("field1"));
.. etc.It's likely that the servlet will store this bean as a request attribute before forwarding to the JSP. It's also likely that you'll have to validate some of the fields, especially if the bean has non - String attributes.
(This is a major area where frameworks like struts or Spring do a lot of this boiler plate stuff for you).

Use of Synchronized in jsp/servlet

Can any one explain me the use of Synchronized in servlet/jsp which is multithreaded Is this correct synchronized should be used only when we want to pritect Static variable as they have only one copy but in case of instance variable they have seperate copy for each instance so no point of synchronized.
Thanks in advance

Hello again,
Take an external file for instance, you open a input stream to it and read data from it in your Java application. You can't have two threads reading at the same time, and one will likely block or throw an exception.
A better example is when your threads need to communicate with each other. If they all communicate via a set of variables that can be read and written to by any of them, then they should be synchronized. You should know if your threads need to communicate with each other? If they do not, there is no need for synchronisation.
What are your threads doing if you don't mind me asking?
I have to admit, I have had little experience using threads, and I have never needed to use threads in JSP (I don ot directly use servlets).
Regards,
Darren

Using public variables in a servlet

Hi, I have a public variable "CustID" in my servlet. Note that is a public member variable and not a static variable.
In the doPost() method, I am trying to use the custId field.
Pls. look at the code below. I want to know that in a multi-user environment since the custId field is defined at Servlet level as a member variable, is there a chance for this variable to be corrupted and I fire a wrong query ???
Awaiting your answers
public class QWCustomerServlet extends HttpServlet
public boolean debug = false;
public QWFieldList fieldList = new QWFieldList();
public String custID = null;
public doPost(HttpServletRequest req, HttpServletResponse res)
HttpSession session = null;
if ( (session = request.getSession(false))!= null){
custId = session.getAttribute("cid");
String query = "select * from customer where cust_id=" + custId;
Statement stmt = conn.createStatement();
stmt.executeQuery(query);
}

Yes. There is only one instance of a servlet and all requests thread through it. Don't use instance variables unless you want all threads to share (usually in a read-only manner such as a reference to a resource). In your example, move the custId declaration inside doPost and it will be thread-safe.

Using getSessionContext() and getIds() in servlets

hello
Problem is getSessionContext() and getIds in servlets are not working at all. I 've a servlet which uses these methods to manupulate sessions what it does'nt work.
getSessionContext() returns session context under which this servlet is running. through this context i want to access all the sessions which are associated with servlet. this context is used with getIds() to get the ids of different sessions. it returns enumeration. but in my case it is always empty even when there are two browsers have valid sessions going on.
so please suggest me some way out
waiting desperately
thanks

As long as you created the session, it should have returned the session id. You may need to post some code.
Bosun

The use of javabean in a servlet

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