Using Servlets in stead of Applets

hi All,
Though I have been in Java Platform for years, I am new to use Java Web-based things. Now I am on a project which is already in Java Applets.
* Java Applets are taking the client machine's configuration and performs some tasks and facilitates the end-user to make print-outs out of the results produced.
* Now, I am on my process to revamp this to some other solution in Java, particularly in JSP and Servlets.
* As I am new to this stuff, I am in need of some conceptual help whether I am able to read the client machine's things from a Servlet and produce the results from a JSP page. If it is possible, will that be faster comparing to the older Version in Applets.
* Can I incorporate Swing for the GUI for the end-user.
Please help me by giving suggestions or by some net materials. Thanks in adv.
bh_t_76

A servlet runs on the server - not the client machine. At the end of the day, it basically produces a web page, which is all the client sees.
- You have little or no control over the client machine
- You cannot access the info on the client machine, apart from standard HTTP headers.
- you cannot incorporate swing - interface is limited to web page and HTML components.
- printing web pages can be troublesome (to say the least)
You may want to check the requirements, and the suitability of a jsp/servlet solution for this application.

Similar Messages

When to use servlets / when applets

hi there,
building a web application when do I use servlet technology and when applets? What are the arguments to let me choose between them? Or combine both servlets and applets? Any ideas/URLs are welcome.
greetings

is it a matter how powerful my servermachine is?
No, not really, but an applet will use the processor on the client and the servlet will use the server's cpu, so that could potentially be an issue for you.
or a matter of security or whatever?
There are security issues with Applets, as they cannot access system resources, but neither can Servlets, so I think that's a non issue.
What exactly do you need to do with the data once you get it out of the database? THAT is the real question! If you want to fetch data and then display the data as text or HTML in a browser, use a servlet. If you need the client to interact with the data in a more sophisticated way, use an Applet. With an Applet, you can put buttons and sliders and whatever and control things, and interact with the application. But a Servlet is not an application, nor is it interactive. A Servlet is called, it gets parameters from an HTTP client, and then it responds, and it's done. An Applet has runtime, and stays running, to interact with the client indefinitely.
I'll give you a real world example. With a Servlet, you might output a web page to a browser, and show an advertisement somewhere on the page. However, an Applet could show an advertisement, and update that ad every few seconds or so, and show one after another, like a slideshow. Even better, an Applet could go get a BRAND NEW ad that was just put in the database and get the new ad at runtime, showing up to the minute results. An Applet could do a stock ticker program, Servlet cannot. Get the difference?

[b]can I use servlets for Chat? new to servlets[/b]

I want to a chat application for someprof and students
I am using multicasting technique to send and receive messages
I used applets and created it but applets don't support java.net's MulticastSocket so I used certificate
Now I want to use servlets for this in JSP because I called applets from JSP
Can it be possible? If yes please clearify.

it is possible
you could create a jsp page that would update like 10 or 20 or whatever number of ServletContext attributes.
in the jsp_service or in the doPost or doGet method of a servlet:
String messageFromUser=request.getParameter("msg");
int num=15;
String[] chat=new String[num];
chat[0]=getServletContext().setAttribute("chatLine" + 0, messageFromUser);
for(int i=1; i<num; i++) {
String previousMessage=getServletContext().getAttribute("chatLine" + (i-1));
chat=getServletContext().setAttribute("chatLine" + i, previousMessage);
out.println(chat[i]);
however, there is a pretty decent client/server chat program that can run as an applet here:
http://planetsourcecode.com/vb/scripts/ShowCode.asp?txtCodeId=4397&lngWId=2

Detecting ram and hard disk using servlet

how to detect RAM and HD using servlet from remote client host. currently i use JIGSAW as JWS...should i use hashtable and runtime class for this problems. please help me...

well...
You can't...
You could use the methods in the Runtime class for memory management but they'll return the corresponding values of the server and not the client (Servlets are Server Side Java Applets).
And most of the hardware specs are hidden to JVM and without JNI programming you are unable to detect any hardware type (HW drivers are usually written in C or even in ASM).
So, learn C, figure out how to access devices at low level programming if the information is so important for you and stop dreaming of accessing computer hardware from the web. It would be a serious security risk if it would be possible ;)
rgds
Sabalasa

URGENT.........File Upload using Servlets and jsp

I am a new servlet programmer.......
iam using tomcat server......
can any one pls help in writing code for file upload using servlets and jsp without using multipart class or any other class like that....
Please URGENT..

Slow down! "Urgent" is from your perspective alone. I, myself, am not troubled or worried in the least.
hi ugniss
thanks for ur reply....sorry i was not
y i was not asked not to use multipart class or any
other class like that...is there any other
possibility to do file uploading from jsp to
servlet...
Just as an aside, a JSP is a Servlet. But even if I move beyond that, the question does not make sense. If you want a "JSP to upload to a Servlet", then simply do so in memory. You are still (likely) within the same scope of a given request. However, if instead you are referring to a JSP that is displayed on a browser, then really you are talking about HTML, which is what the browser will receive. And since you are now talking about a browser, your only real, viable option is a multi-part file upload. So, it is either server or it is browser. And either way, the question leads to very established options, as outlined above.
the main concept is.. in the browser the user selects
a particular file and clicks the button upload..after
clicking upload the jsp should sent the file to the
servlet in streams...there the servlet gets in and
saves in a server location........this is wat i hav
to do...
Okay. So, after reading my previous (redundant) paragraph, we have arrived at the crux of the issue. You have a JSP that will be output as HTML to a client (browser) which you want to upload content to your server (handled by a Servlet). So, you are now stuck again with multi-part. The requirement to not use multi-part is non-sensical. You can overcome it, say, if you write your own applet or standalone Swing client. However, if your users are invoking this functionality from a browser, you are limited by the options that W3C has provided you. Use multi-part.
is there aby possibilty to do this.....can any one
pls help....Take the advice to download and review Jakarta Commons FileUpload. Inform your management that their requirement makes no technical sense. Research on your own. There are dozens of examples (and tutorials) on file upload using multi-part. Embrace it. Live it. Love it.
- Saish

Open Jasper Report in new page using servlet

Guys,
Looks very simple but i am having problem making this process work. I am using 11.1.1.4
This is my use case:
- From a employee page, user clicks on a menu item to open report for current employee. I need to pass appropriate report parameters to servlet and open report into new page.
I can successfully call servlet using commandmenuitem and set request parameters and call servlet from backing bean.... but that doesn't open report in a new page.... any way i can do this?
Another option i tried was that using gomenuitem and setting target=blank but in that case i need to pass the parameter using servlet url which i like to avoid.(in case i need to pass many parameters in future) (also values will be set on page so i need to generate url when then click the menuitem...... so there are some hoops and loops i need to go through) I don't know a way to pass the request parameter using backing bean to servlet... i don't think it is possible.
Those are the two approaches i tried.
If you have any better approach...I would appreciate if you can let me know. (i have searched on internet for two days now.... for the solution)
-R
Edited by: polo on Dec 13, 2011 7:22 AM

Hi,
Hope following will useful
http://sameh-nassar.blogspot.com/2009/10/using-jasper-reports-with-jdeveloper.html
http://www.gebs.ro/blog/oracle/jasper-reports-in-adf/

How to define target window when redirecting within frames using servlet?

Howdy:
Is there a way to define target window when redirecting within frames using servlets?
How to do it in JSP as well?
T.I.A.
Oriental Spirit

Your servlet (or JSP) can't decide where it is going to be displayed. The browser has already decided that when it makes the request to your servlet.

Using servlet to generate XML file

What I want to do is simple but can't work. Hope you guys can give me a hint.
I succesfully generate XML file in command line using Oracle XML parser and class generator. Then I was trying to do it using servlet. it compiles fine but generate NullPointer exception at the line:
Emp e1= new Emp(); //Emp is the root of XML
I suspect the Emp constructor can't correctly find the globalDTD in its superclass -CGDocument. Please note this only happens in servlet setting, not is command line setting. Any suggestion to get arounf this?
Another unrelated question is that when I create a XML file using the Oracle XML parser, it seems all the elements a file has to be added once, otherwise the compiler will compalain about the missing element. this will be inconvinient when I constructing a big XML file, which I 'd liek to split into small piece and add them up. Maybe there is a good way but I just don't know it.
my email: [email protected]

Hi,
I'm running into the same problem deploying the classes generated by the class generator. Code works fine from JDeveloper, but had to put my DTD in the directory where my classes are. Deploying the classes with Apache's JServ gives me a NullPointer exception on the first addNode method. I guess it can't find the DTD. I tried to put the DTD in many locations but this didn't fix the problem. Any suggestions?
Steve,
Did you fix this problem? Thanx!
null

How do i call the method in a class using servlet

i am doing a project which need to use servlet to call a few methods in a class and display those method on the broswer. i tried to write the servlet myself but there are still some errors .. can anyone help:
The servlet i wrote :
package qm.minipas;
import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class test extends HttpServlet {
Database database;
/** Initializes the servlet.
public void init(ServletConfig config) throws ServletException {
super.init(config);
database = FlatfileDatabase.getInstance();
/** Destroys the servlet.
public void destroy() {
/** Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
* @param request servlet request
* @param response servlet response
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
response.setContentType("text/html");
java.io.PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet</title>");
out.println("</head>");
out.println("<body>");
out.println("this is my class wossname"+FlatfileDatabase.getInstance()); // this is calling the toString() method in the instance of myJavaClass
out.println("this is my method"+FlatfileDatabase.getAll());
out.println("</body>");
out.println("</html>");
out.close();
/** Handles the HTTP <code>GET</code> method.
* @param request servlet request
* @param response servlet response
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
processRequest(request, response);
/** Handles the HTTP <code>POST</code> method.
* @param request servlet request
* @param response servlet response
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
processRequest(request, response);
/** Returns a short description of the servlet.
public String getServletInfo() {
return "Short description";
my methods which i need to call are shown below:
public Collection getAll() {
return Collections.unmodifiableCollection(patientRecords);
public Collection getInpatients() {
Collection selection=new ArrayList();
synchronized(patientRecords) {
for(Iterator i=patientRecords.iterator(); i.hasNext();) {
PatientRecord next=(PatientRecord) i.next();
if(next.isInpatient())
selection.add(next);
return Collections.unmodifiableCollection(selection);
public Collection getByAdmissionDate(Date dateOfAdmission) {
List selection=new ArrayList();
for(Iterator i=patientRecords.iterator(); i.hasNext();) {
PatientRecord next=(PatientRecord) i.next();
if(dateOfAdmission.equals(next.getDateOfAdmission()))
selection.add(next);
return Collections.unmodifiableCollection(selection);
public Collection getByAdmissionDates(Date from,Date to)
throws IllegalArgumentException {
if(to.before(from))
throw new IllegalArgumentException("End date must not be before start date");
List selection=new ArrayList();
for(Iterator i=patientRecords.iterator(); i.hasNext();) {
PatientRecord next=(PatientRecord) i.next();
Date nextAD=next.getDateOfAdmission();
if((nextAD.after(from)||nextAD.equals(from))
&&(nextAD.before(to)||nextAD.equals(to)))
selection.add(next);
return Collections.unmodifiableCollection(selection);
public Collection getByDischargeDates(Date from,Date to)
throws IllegalArgumentException {
if(to.before(from))
throw new IllegalArgumentException("End date must not be before start date");
List selection=new ArrayList();
for(Iterator i=patientRecords.iterator(); i.hasNext();) {
PatientRecord next=(PatientRecord) i.next();
Date nextAD=next.getDateOfDischarge();
if(nextAD==null)
continue;
if((nextAD.after(from)||nextAD.equals(from))
&&(nextAD.before(to)||nextAD.equals(to)))
selection.add(next);
return Collections.unmodifiableCollection(selection);
public Collection getByConsultant(String consultant) {
List selection=new ArrayList();
for(Iterator i=patientRecords.iterator(); i.hasNext();) {
PatientRecord next=(PatientRecord) i.next();
if(consultant.equalsIgnoreCase(next.getConsultant()))
selection.add(next);
return Collections.unmodifiableCollection(selection);
public Collection getByDischargeDate(Date dateOfDischarge) {
List selection=new ArrayList();
for(Iterator i=patientRecords.iterator(); i.hasNext();) {
PatientRecord next=(PatientRecord) i.next();
if(dateOfDischarge.equals(next.getDateOfDischarge()))
selection.add(next);
return Collections.unmodifiableCollection(selection);
public Collection getBySurname(String surname) {
List selection=new ArrayList();
for(Iterator i=patientRecords.iterator(); i.hasNext();) {
PatientRecord next=(PatientRecord) i.next();
if(surname.equalsIgnoreCase(next.getSurname()))
selection.add(next);
return Collections.unmodifiableCollection(selection);
public Collection getByWard(String ward) {
List selection=new ArrayList();
for(Iterator i=patientRecords.iterator(); i.hasNext();) {
PatientRecord next=(PatientRecord) i.next();
if(ward.equalsIgnoreCase(next.getWard()))
selection.add(next);
return Collections.unmodifiableCollection(selection);

please provide a detail description of your errors.

How to invoke a jsp page from java which does not use Servlets?

Hello,
I am working in Documentum. I am trying to invoke a jsp page from another java page which does not use Servlets.
I tried doing this by just instantiating the java class related to the jsp page from my present java class.In my java class related to the jsp page, I have defined onInit() and onRender() methods.
Now, I am trying to call the jsp page from my present java class by just instantiating the java class related to the jsp page. This throws a java.lang.NullPointerException.
Any comments or suggestions on this.Any help would be appreciated.
Thanks,
Ranjith M.V

RanjithM.V wrote:
Hello,
Thanks for the reply. One important thing I forgot to mention. I am also using xml component.And?
As this is the standard way used for coding in Documentum, I do not want to use Beans.Well, JSP's should, in and of themselves, contain no functional code. It should all be only display.
Without that is it not possible?What did I say? I said,
masijade wrote:
It is possible, but I very, very, very, much doubt, that it would be worth the effort.And, if you don't know how, a forum is not truely going to be able to help you implement it (at least not in less than a few years time, at which point it would be outdated).
>
Appreciate your understanding and help.
Thanks,
Ranjith M.V

Uploading a file to server using servlet (Without using Jakarta Commons)

Hi,
I was trying to upload a file to server using servlet, but i need to do that without the help of anyother API packages like Jakarta Commons Upload. If any class for retrieval is necessary, how can i write my own code to upload from client machine?.
From
Velu

<p>Why put such a restriction on the solution? Whats wrong about using that library?
The uploading bit is easy - you put a <input type="file"> component on the form, and set it to be method="post" and enctype="multipart/form-data"
Reading the input stream at the other end - thats harder - which is why they wrote a library for it. </p>
why i gave the restriction is that, i have a question that <code>'can't we implement the same upload'</code>
I was with the view that the same can be implemented by our own code right?

Using a filechooser in an applet

Is it possible to use a filechooser for an applet save button? If so how can you do it? So far I have only been able to use the filechooser object with JFrame and not JApplet.

Hi,
I'm a newbie, but I just had a similar problem and the solution was in the html code to display the applet. here's the code:
<applet width=700 height=500 code="ImageExample.class"> </applet>
make sure the height and width here are big enough for your imaage.
HTH
Paul

Using a main in an Applet

Hello, I have a question.
How do you use a mian in an Applet.
Eample, after an applet section is complete, I want it to go into Console use. Does anyone know how to combine the two? Thanks
Note: So far, I got the program to go into the Console but It stops working when it asks for user input. There are no "String args[]" and that is what I hypothesis is the error

import javax.swing.*;
public class MyApplet extends JApplet {
     public void init() {
          //init stuff here
     public void start() {
          //start stuff here
     public static void main(String[] args) {
          JFrame f = new JFrame();
          JApplet a = new MyApplet();
          f.getContentPane().add(a);
          f.setSize(600, 400);
          f.setVisible(true);
          f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          a.init();
          a.start();
}Excuse me, but is there a way to do this on Applet only instead of JApplet... I was told we need to use Applet only...

Displaying results from a database query using servlets

I have this HTML form where users can search a MS Access database by entering a combination of EmployeeID, First name or last name. This form invokes a Java Servlet which searches the database and displays the results as an HTML page. I am giving the user the choice of displaying 3, 5 or 10 results per page. I want to know how to do that using servlets. If a particular search results in 20 results, the results should be displayed in sets of 3, 5 or 10 depending on the user's choice. If the user makes a choice of 5 results per page then 4 pages should be displayed with a "next" and "previous" button on each page. I want to know how this can be done.

Arun,
I'm not sure how to do this using JSP as I have not worked on JSP.
But I can give you a hint on how to do this within normal java class as I've used this in my current project.
In your core class/bean that generates the entire resultset, you need to run a loop that will scan through the desired number of records in the resultset.
To do this, you have to have skip and max parameter in your URL.
Somthing like http://server.com/myservlet?skip=0&max=10 to display first 10 records, http://server.com/myservlet?skip=10&max=10 to display next 10 records. The <next>parameter would be fed in by the user by a simple form in your web-page. If you need to hold this <max-num-of-recs-per-page> param, you can store it in a cookie (since this is nothing crucial piece of info, don't need to use session obj etc...cookie will do) and get the value each time you display the resultset.
So, essentially, suppose you are at the first page and you wish to show 10 recs at a time. The link for "Next" button would be http://server.com/myservlet?skip=10&max=10
when at the second page, you'll have
"priv" button as http://server.com/myservlet?skip=0&max=10 and
"next" button as http://server.com/myservlet?skip=20&max=10 and so on...
hope this makes sense..
Shantanu

Cache file(pdf) in user's browser using Servlet -Cookie, or Session

How can I save a file (pdf) in the cache of a browser (IE 6) in a user's computer? I am using Servlet and Tomcat 4.1.24. PDF file is sitting in server (remote computer) under a URL space.
The idea is to NOT to download the pdf file on user's computer (from the remote server) if the user has a cached copy of the pdf file and pdf file in the server is the same as the pdf file in the browser. If cached pdf is different from pdf in browser, or, if the user does not have that pdf file in cache, then download pdf file from the server.
Can I come up with a way to use Cookie class? Cookie class does not have an API which will let me save a file in it. I could have saved the pdf file in the Cookie with 999999999 setMaxAge. Is storing that pdf file in session the only choice? I do not see session serving my purpose - session should not be valid for a longgg duration e.g. week or month.
Also, how would I create a file whne I am given a URL to that file.
URL fileInServer = new URL("http://www.myDomain.com/myWebApp/PDF/my.pdf);
URLConnection conn = fileInServer.openConnection();
Does getContent() help and what are the steps after that?
Any help with the source code will be appreciated.
Thanks,
Sam
[email protected]

I am NOT creating this PDF file on the fly. This pdf file is sitting in the server (remote machine) under URL e.g. http://10.10.10.xxx:8081/myApp/PDF/my.pdf
I need to check if this pdf file is in the cache in user's computer (differnt machine than the server) and if the cached pdf is the same as the pdf in the server. If that file is not in the cache, or if they are not the same, then, I need to save the pdf file from the server into user's browser cache.
I am writing all that code in Servlet. I can save the file in session. I do NOT know how else can I cache the file, other than saving it in session. I can not think of any setHeader() which will let me save a file in user's browser cache. Headers like If-Modified-Since are of no help, as it does not let me compare file in browser cache with the file in server.
Also, how would I create a file, given a URL to that file.
URL fileInServer = new URL("http://www.myDomain.com/myWebApp/PDF/my.pdf");
URLConnection conn = fileInServer.openConnection();
Do I use getContent()? What are the steps after that?
Thanks,
Sam
[email protected]

Using Servlets in stead of Applets

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