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Class oncore.Main
java.lang.Object
|
+----javax.servlet.GenericServlet
|
+----javax.servlet.http.HttpServlet
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+----oncore.Main
- public class Main
- extends HttpServlet
Main servlet in the program. This handles almost all ( except the one
which request student information ) the requests. Any servicing of query
needs the user to have been authenticated before. Since HTTP is stateless
the state of authentication is maintained by cookies ( cookies are handled
by the class HttpServlet by itself, so that we need not write any code to
do that ). All the data which may depend on the context is read from
configuration file.
-
Main()
-
-
doGet(HttpServletRequest, HttpServletResponse)
- Method which will get called when a user tries to access the servlet
for the first time.
-
doPost(HttpServletRequest, HttpServletResponse)
- Method which gets called every time use submits some query.
-
getServletInfo()
-
-
init(ServletConfig)
- Method which does initialisation stuff in the Servlet.
Main
public Main()
init
public void init(ServletConfig cfg) throws ServletException
- Method which does initialisation stuff in the Servlet. This gets
hajjaar things as startup parameters ( please refer he props file for
details ) and create a new Configuration object to initialize all the
fields of Configuration.
- Parameters:
- cfg - This is ServletConfig object passed to the method by servlet
engine. This contains all initArgs.
- Throws: ServletException
- Thrown when kernel ( servlet ? ) panic ( ie
fatal error ;-) occurs in initialisation.
- Overrides:
- init in class GenericServlet
doGet
public void doGet(HttpServletRequest req,
HttpServletResponse res) throws ServletException, IOException
- Method which will get called when a user tries to access the servlet
for the first time. This method gets invoked when the browser sends
http request of the form GET http://.../servlet/Main HTTP/1.1. This
method just sends back the login page.
- Parameters:
- req - The request from user which requests initial page.
- res - The response to be submitted to user.
- Throws: ServletException
- thrown when some problem with servlet
engine.
- Throws: IOException
- thrown when socket I/O goes wrong.
- Overrides:
- doGet in class HttpServlet
doPost
public void doPost(HttpServletRequest req,
HttpServletResponse res) throws ServletException, IOException
- Method which gets called every time use submits some query. Servlet
engine will automatically invoke this method whenever the browser
submits the HTTP request in the format:
POST http://.../servlet/Main HTTP/1.1
Very crucial method since this method decides to whom control should be
transferred.
- Parameters:
- req - The request submitted to the servlet engine.
- res - The response to be submitted to the user.
- Throws: ServletException
- Thrown when some fatal error occurs with
the servlet.
- Throws: IOException
- Thrown when error in socket I/O occurs.
- Overrides:
- doPost in class HttpServlet
getServletInfo
public String getServletInfo()
- Overrides:
- getServletInfo in class GenericServlet
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