How to implement a RequestDispatcher, so I checked tomcat's source code, the ApplicationDispatcher class, but there are many places I can't understand.
I found in the ApplicationDispatcher class that the method used to forward request and response to the designated resource is the invoke(ServletRequest,ServletResponse) method, and this part is responsible for executing forward:
support.fireInstanceEvent(InstanceEvent.BEFORE_DISPATCH_EVENT,
servlet, request, response);
// for includes/forwards
if ((servlet != null) && (filterChain != null)) {
filterChain.doFilter(request, response);
}
// Servlet Service Method is called by the FilterChain
support.fireInstanceEvent(InstanceEvent.AFTER_DISPATCH_EVENT,
servlet, request, response);
I can't understand this part of code, does this mean the RequestDispatcher.forward() and RequestDispatcher.include() methods are all executed in a filterchain? What is the mechanism of it?
When we forward the request to a jsp , I noticed that the url bar address does not change .
I made a form form.html , and set action to a servlet then in servlet class I set an attribute and forward the request to jsp ,which prints the value of that attribute.But the url in address does not actually points to that jsp to which i forwarded the request.
For some reason, even though I am giving it the correct number of arguments for the constructor to be initalized it doesn't go through. I end up with a compile error:
PatientBuilder.java:17: error:
constructor Patient in class Patient cannot be applied to given types; Patient aPatient = new Patient(bloodType, rhFactor, ID, age); ^ required: no arguments found: String,String,int,int reason: actual and formal argument lists differ in length
And I'm not understanding how that's possible when it calls for 2 strings and 2 ints and that's what I am passing.
I have this in my main method Scanner inputDevice = new Scanner(System.in);
System.out.println("What is the patients ID number?"); int ID = inputDevice.nextInt(); System.out.println("What is the patients age?"); int age = inputDevice.nextInt();
[Code] ....
And then here are my two constructors, one default and one overloaded.
public Patient() { patientBlood = new BloodData(); ID = 0; age = 0; bloodType = "O"; rhFactor = "+";
I want to make several classes which extend different objects and add additional functions to simplify them and make their purpose in my projects more narrow and make their instances easier to use. So an example, Image class which extends BufferedImage and the constructor in Image class directly loads the file without having to create it first and then have to use Try Catch and all that additional code. Now, here is where my question comes in. Can I make an class, an abstract class or something which can be IMPLEMENTED into these several classes such as the Image class, and in doing so those several classes will have to have (like unimplemented methods) a HashMap<String key, ChildClass instance_as_value>, child class being the Image class as an example.
So I would have something like public class Image extends BufferedImage implements Library, and this class, because it implements Library will have a HashMap<String key, Image value> in it or it's parent class.
import java.util.concurrent.TimeUnit; import java.util.concurrent.atomic.AtomicInteger; import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.Lock; public class tree_lock_test{ int total_instances; int thread_instances = 0; int N;
[Code] .....
this is compiled with another Peterson class which has implemeted peterson lock for two threads ...
So I'm trying to build a queue, first in first out, (so add to the head remove from the end) using a linked list for use in another program, I'm having a problem dequeueing where the program seems to run indefinitely without giving an answer, so my suspicion is its caught in a while loop but how and why I can't figure out.
public class CircularQueuelist { private Node head = null; private int size = 0; private class Node { int data; Node next;
[Code] ....
My logic seems sound, I basically look for when the second node over from the current one I'm on is a reference to the head, and then skip the one in front of it using setting currents. next link to current.next = head, severing the link to the last node.
This is what my driver looks like, I enqueue items 1-10 and then use the iterator to make sure it worked out fine and check size, its when I dequeue that I run into a problem, the program runs indefinitely.
public class Queuetest { public static void main(String[]args) { CircularQueuelist test = new CircularQueuelist(); for (int count = 0; count < 10; count ++)
i am having a problem while calling a method..i am having a class
Java Code:
public class MySer implements Runnable { public void getMessage(String msg) { ..., }.., } mh_sh_highlight_all('java'); i use the above class in another class
I am trying to use iText to create a PDF document. I found a nice tutorial online but one thing stumps me. How do I get the URL of the JSP page that contains the content? Since this will not be static, I don't want to hard code this. I am sure this is something simple but I am fairly new to servlets and JSP.
I tried to visit my webapp with /appinfo appended after the context url but I get a 404 and I see no errors in the GlassFish4 log.
My project is using JSF 2.x with the viewservlet mapped on *.xhtml and it is using Spring Beans as well (using the Spring Context Loader), mapped to /rest/*. Do I need to map something else?
I can only get this servlet working without annotations but only using the old web.xml way.
I don't know what I need to do to get my servlet working with annotations.
So that I can map the first request coming say www.xyz.net to my first page , it does the work but some of my css and images is not getting displayed .
I am new to Servlets and came across it in Head First Java 2nd Edition. I wrote the servlet code. I don't know how to run it. Do I need to set up a server?
Suppose we have two servlets runing inside same war on same server. When user access servlet A and create a session, he then open another tab or browser to access servlet B (session created by servlet A still exist). Inside servlet B, does
I'm trying to go back to basic and strengthen some of my foundation. I'm wondering what kind of data would be appropriate to be stored inside a session? My app is a web app where all the users are the employee of a company. So it's an web-based app that keeps track of stock movements, purchasing and sales order (standard distributor company). The web app interacts strictly with employees, so no public facing app (yes, that's right, no shopping cart). So, in this kind of web app, what kind of data that by storing it to session.
I am calling a jsp page from my servlet using the requestdispatcher.forward(myjsp.jsp) method. myjsp.jsp is creating a new thread which is parallely processing along with the servlet. The issue is that the jsp page is not displayed until the servlet finishes its execution, although the new thread is created by jsp and is executing in parallel. How do we have the jsp page displayed even when the servlet is executing.
I have a secured Struts application in WebSphere that uses FORM j_security_check for authentication.There is also a Post Logon "filter" defined which runs some code after a login is processed.The extract from web.xml showing the login configuration and filter is as follows:
If a user isn't logged into the application and they try to access one of the secured servlets, for example quotes.do, they are directed to the login page to enter their information.If they login successfully, they are then directed to quotes.do, rather than the default "welcome" page. Is there a setting in the web.xml or the post logon filter where I can force j_security_check to ALWAYS go to the default welcome page after a successful login?
I need to encode the URL in order to prevent XSS security threat. I don't have to encode the complete URL, I just have to encode the values for query string. How to encode only the values of query string parameters and change it in the URL itself using java. I am planning to do this in a filter.
I am trying to finish this servlet that adds a new course to my courses display. im using a check box so the user can pick what the prerequisite are for the new course they want to add. so if they check cs201 , it will add cs201 as a prerequisite for that new course.
for some reason my checkbox will only add the first checkbox that is clicked. like if i add a subject , and click the check boxs for cs203 , cs202, and cs201. it will only grab cs201 and add it to my course display. it wont grab all 3. how can i grab the other info thats checked?
I am seen that ASP.NET apps have a handy feature called URL Routing. How will one implement this in Java without the use of heavy frameworks like Spring MVC ? How do you even begin writing a URL Router if there isn't anything available?
I did a Servlet and a JSP with a combobox. I called the JSP on one browser and selected value n1 from the combobox. From another computer, I called the (same URL) and selected value n2. I expected the Servlet to handled both requests separately, however when I select value n2 on the 2nd browser, the jsp on the 1st browser that initially had value 1, now changes into value 2 as well.
Why cant the servlet handle requests separately? users actions on different browsers should not interfere with each other..!
I am trying to build a basic online exam app.But not able to find out how to do that.So user will log in , click on start exam That will be handled by servlet , servlet should call Model class that will fetch questions from database and make a list of those questions and return it to servlet.Than servlet will set that list as an attribute.
and redirect to jsp , which will have three buttons previous ,next ,finish.on clicking on finish I will call servlet wichich will calla model class which returns users score and then servlet redirects to result.jsp.Is this way is right ?
I have good knowledge of servlet,jsp. I've also worked on mvc pattern and now looking to learn a web framework but i'm not sure which to choose between spring mvc OR struts.Should i first do struts and then go for spring or can i choose spring directly?
