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

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Uploading a file using jsp and com.oreilly.servlet lib package

Sorry to bother you but I need your help folks
I am developing an application to pick up files from a database and sent to a specified location on a different system.
I am presently trying to run this code,I have placed this lib package from oreilly which is supposed to encapsulate the usage of file uploads,which is a jar file called cos.jar into C:\Program Files\Java\jdk1.5.0_03\jre\lib\ext folder .I have a jsp page that calls the bean which does the upload and implement the classes in the oreilly package.I am using tomcat 5
[b]the jsp page that acts as the user interface
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>Please Choose The File</title>
</head>
<body bgcolor="#ffffff">
<table border="0"><tr>
<form action="Upload.jsp" method="post"
enctype="multipart/form-data">
<td valign="top"><strong>Please choose your document:</strong><br></td>
<td> <input type="file" name="file1">
<br><br>
</td></tr>
<tr><td><input type="submit" value="Upload File"></td></tr>
</form>
</table>
</body>
</html>
this is the jsp page that calls the bean
<jsp:useBean id="uploader" class="com.UploadBean" />
<jsp:setProperty name="uploader" property="dir" value="<%=application.getInitParameter(\"save-dir\")%>" />
<jsp:setProperty name="uploader" property= "req" value="${pageContext.request}" />
<html>
<head><title>file uploads</title></head>
<body>
<h2>Here is information about the uploaded files</h2>
<jsp:getProperty name="uploader" property="uploadedFiles" />
</body>
</html>
[b]this is the bean class
package com;
import java.util.Enumeration;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.ServletRequest;
import com.oreilly.servlet.MultipartRequest;
import com.oreilly.servlet.multipart.DefaultFileRenamePolicy;
import javax.servlet.*;
public class UploadBean {
private String webTempPath;
private HttpServletRequest req;
private String dir;
// private ServletRequest request;
public UploadBean( ) {}
public void setDir(String dirName) {
if (dirName == null || dirName.equals(""))
throw new IllegalArgumentException("invalid value passed to " + getClass( ).getName( )+".setDir");
//webTempPath = dirName;
dir = dirName;
/* public String getDir()
return webTempPath;
public void setReq(ServletRequest request) {
if (request != null && request instanceof HttpServletRequest)
req = (HttpServletRequest) request;
} else {
throw new IllegalArgumentException("Invalid value passed to " + getClass( ).getName( )+".setReq");
public String getUploadedFiles( ) throws java.io.IOException{
//file limit size of 5 MB
MultipartRequest mpr = new MultipartRequest(req,dir,5 * 1024 * 1024,new DefaultFileRenamePolicy( ));
Enumeration enume = mpr.getFileNames( );
StringBuffer buff = new StringBuffer("");
for (int i = 1; enume.hasMoreElements( );i++){
buff.append("The name of uploaded file ").append(i).append(" is: ").append(mpr.getFilesystemName((String)enume.nextElement( ))).append("<br><br>");
}//for
//return the String
return buff.toString( );
} // getUploadedFiles
On running the code I find this error messages
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
javax.servlet.ServletException: javax/servlet/ServletRequest
     org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:848)
     org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:781)
     org.apache.jsp.jsp.Upload_jsp._jspService(org.apache.jsp.jsp.Upload_jsp:73)
     org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
     org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:322)
     org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:291)
     org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
root cause
java.lang.NoClassDefFoundError: javax/servlet/ServletRequest
     com.oreilly.servlet.MultipartRequest.<init>(MultipartRequest.java:222)
     com.oreilly.servlet.MultipartRequest.<init>(MultipartRequest.java:151)
     com.UploadBean.getUploadedFiles(UploadBean.java:49)
     org.apache.jsp.jsp.Upload_jsp._jspService(org.apache.jsp.jsp.Upload_jsp:63)
     org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
     org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:322)
     org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:291)
     org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.9 logs.
Apache Tomcat/5.5.9
tanks

Hi,
Looks like you are missing a file from the classpath. Make sure servlet.jar is available in your classpath. Ordinarily files in <tomcat_home>/lib directory should be added automatically. You need to check why it hasn't been added in your case. A good place to start would be the bat files in the bin directory viz startup.bat, catalina.bat etc.
cheers,
vidyut

Need Help Badly on Shopping Cart Using JSP And Java Servlet

Hi All,
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How i do store all the items user has selected ... everytime he would wan to view his cart ...
As i would be calling from jsp to servlet .. or jsp to servlet ... and i do not know how i should go about in creating the shopping cart.

Hi !
Yon can use a data structure as vector and store the items selected by the user into the vector . Keep the vector in session using session object , so the user can access the entire shopping cart from anywhere in the application .
Then , you can change the cart accordingly .
Hope this works.
Cheers ,
Pranav

Showing various images on browser using JSP and Servlet

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THANK YOU !
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If I understand correctly what your problem is:
Do this in the jsp:
out.println("<img src=\"ShowImg?image=" + intI + "\" WIDTH=100>");
In the image servlet, get the "image" parameter and parse it as an int. Move the Imagem.IndicarImagem() call to the image servlet.

When to use jsp,and when to use servlet?

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IMHO I use servlets to control the flow between my jsp's based on a number of factors in a webapp. For instance, user authorization. If a user has the authorization to conduct various administrative functions on an application (like change user rights, reset passwords etc) they will have access to specific buttons or links on some screens that others will not. I use servlets to establish what access rights a user has and direct them to the appropriate pages. I also use servlets to test data validity on form input screens. I know that I can also do this with JavaScript but that can be disabled by the client and in order to prevent that I also double check the form input from a servlet. All my jsp's do is display the results of a business process (which is held in a JavaBean or EJB) and the servlets act as the controllers for the application, connecting to multiple databases, verifying application state, flow control etc. I try to keep the jsp as simple as possible as some of them are maintained by html developers who lack the necessary experience to write java code. I hope this helps.

Question regarding use of Log and LogFactory in Servlets

Hi,
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corresponding action mapping
<action path="/FilePathAction" type="actions.FilePathAction">
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So plz help me to upload a file to the server from any PC.
Iam searched alot but didnt get any solution.

Plz help me soon if it possible so
Iam in great need.
I have worked alot but not worked out.
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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 :-)
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So its not so much a limitation of beans, but just the environment you run the code in.
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For the rest you might consider the DAO pattern. Or ignore SQL altogether and let hibernate do the work there for you.
Cheers,
evnafets

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In my application I am having:-
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3)- a servelet and a jsp.
In servlet I want to fetch entire data of the table and want to assign the values to the setters of the bean.
in jsp I want to call that bean and want to use its getters to display the entire profile of the user.
I am finding compleatly unable to use the bean in the servlet, please help me out.

hi,
try like this..
after fetching all of your datas
store in setter method of the bean.
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Managing blob images using ADF and JSF or struts

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jfin wrote:
but so far I have to say that I like the fact that I'll have to do very little
System.out.println(<..../>....<>....</>).Assuming that you rather mean out.println() where out is the ServletOutputStream reference returned by HttpServletResponse#getOutputStream(), I can only agree with you. That's certainly not the way how JSP/Servlet code is to be written. The maintainability, extendability, reusability and testability would be far below the freezing point then. You need to write presentation logic in JSP files, not in Servlets and absolutely not in scriptlets inside a JSP.
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I'm having trouble finding documents show how one should use databases and listen for container events? I'm using Berkley Java DB. I'll need all my remote object to have access to the database. How do I pass that in? Custom adapters? Also, when Tomcat shuts down I need to close the database, how would this be down? Custom adapters? So I may be answering my own question, but I'm asking cause I really don't see anything in the documentation that points this out. It really looks like I'd be using singletons and factories for this. I could register a Servlet or Servlet Context to listen for Tomcat events, but I figured it couldn't hurt to ask others using Blaze, as I'm very new to it. Thanks.

So how would you tell Blaze to use this? Is there something you put into the config file? My thoughts on all this is to use PicoContainer to manage all services then create an adapter to inject all resources when creating remote objects. But this seems a little heavy if Blaze can do all this for me. The adapter seems like the injection point to me. Is that not what it's used for? Or is using it like that bad practice under Blaze? I've read all I can find on Blaze, so either it's missing docs, or I'm not finding them all. If I'm missing them, by all means let me know where to go. I don't want to ask questions that are already answered in documents else where.
On Tue, May 20, 2008 at 10:51 AM, Mete Atamel <
[email protected]> wrote:
A new message was posted by Mete Atamel in
General Discussion --
  Using databases and container events?
I think it's mainly in JavaDocs but here's a sample I have where I check to make sure the HSQLDB is running as the BlazeDS starts up:
import java.sql.Connection;
import java.sql.SQLException;
import flex.messaging.config.ConfigMap;
import flex.messaging.services.AbstractBootstrapService;
public class DatabaseCheckService extends AbstractBootstrapService
    // This is called right before server starts up.
    public void initialize(String id, ConfigMap properties)
        Connection c = null;
        try
            // Check that the database is running...
            c = ConnectionHelper.getConnection();
            // ... if yes return
            return;
        catch (SQLException e)
            System.out.println("DB is not running!");
        finally
            ConnectionHelper.close(c);
// This is called as server is starting.
    public void start()
        // No-op
// This is called as server is stopping.
    public void stop()
        // No-op
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Using databases and container events?
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"All that is necessary for the triumph of evil is that good men do nothing." - Edmund Burke

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

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

Can I use SimpleFdkCredential() from within a servlet?

I have a test program that logs in to content DB using SimpleFdkCredential, and works perfectly well run from the main() method of a Java class from within JDeveloper. When I try to login the same way from within the doGet() method of a servlet, doGet() hangs on the call to ManagersFactory.login() using the same SimpleFdkCredential that works in-process. The login() call doesn't throw any exceptions, it just sits there waiting[I presume], and never returns.
Is it necessary to use S2SFdkCredential for any authentication that originates from a servlet invocation? It seems that SimpleFdkCredential should work in this instance as well.
Thanks.

Can you check the Content DB http node log (application.log) with debug log level set, to see if the request from the servlet for the RemoteLoginManager Web Service was received?
I would also check that all libraries are present/accessible from servlet - and that there are no conflicts with existing libraries.
Also, check the servlet log for anything strange.
Finally, you could try remote debugging of your servlet .. e.g -Xdebug java option.
-Matt.

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