Hi Geeta,
I wonder which is best way to connect to database and get your job done.
Right Now what i am doing is :
JSP -> Bean -> Database
Database ->Bean->JSP
I am opening the connection in the Beans Constructor.
Whether there is any flaw in this approach if not how best can i improve
this model.
With Regards,
b.karthikeyan.
----- Original Message -----
From: Geeta Ramani <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, August 01, 2001 8:36 PM
Subject: Re: Refresh servlet page problem
>
> Hi Andrew:
>
> I think this is your problem: you are opening your connection in the
init()!
> init() is executed *just* once at servlet initialization time and *not*
every
> time a person posts (or gets)! So what is happening is your connection is
opened
> at init(), closed after the first doGet() and further doGets() don't have
> connection to work with (hence a null pointer exception). So this is what
you
> should do:
> Create and close the connection in the doGet()/doPost() and I believe your
> troubles will be over. (You would do well to create a connection pool in
the
> init() and then get and release connections from the pool, but that's
another
> story..)
>
> Geeta
>
> andrew tollin wrote:
>
> > Thank you Marco,
> >
> > I have attempted to close the statement along with the connection within
the
> > doGet method as follows:
> > finally {
> > file://close the database connection.
> > try {
> > if (stmt !=null) stmt.close();
> > if (con !=null) con.close();
> > }
> > catch (SQLException e) {}
> > }
> >
> > I open the connection in the init() method as follows. I dont quite
> > understand what my problem is! Help
> >
> > public void init(ServletConfig config)
> > throws ServletException
> > {
> > super.init(config);
> > try {
> > // Loads the driver
> > Class.forName("org.gjt.mm.mysql.Driver");
> >
> > // Get a Connection to the database
> > con = DriverManager.getConnection (url);
> > }
> > catch (Exception E) {
> > System.err.println("Unable to load driver.");
> > E.printStackTrace();
> > } // end catch
> >
> > ----- Original Message -----
> > From: "Marco Trevisan" <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Wednesday, August 01, 2001 9:36 AM
> > Subject: Re: Refresh servlet page problem
> >
> > > Looks like the first time the servlet is invoked it works OK.
> > > Subsequent invocations mess up the connection (never
> > > worked on mysql but I'd close and reopen the connection
> > > or better use a connection pooling package, maybe stmt
> > > isn't being closed).
> > > When you open via the address bar I suspect you get the
> > > cached HTML produced the first time.
> > >
> > > Marco
> > >
> > > ----- Original Message -----
> > > From: andrew tollin
> > > To: [EMAIL PROTECTED]
> > > Sent: Tuesday, July 31, 2001 10:14 PM
> > > Subject: Refresh servlet page problem
> > >
> > >
> > >
> > > Hello
> > >
> > > I have a problem with my servlets. I have created a number of servlets
> > that
> > > connect to a database, access a particular table, and insert the
database
> > > information into skeletal HTML. When I view my page on Tomcat port
> > > 8090(changed from port 8080 due to DB probs) by entering
> > > http://localhost:8090/servlet/UsefulAddresses for example, it loads
with
> > no
> > > errors. However when I refresh the page I get this error:
> > >
> > > Error: 500: Location: /servlet/UsefulAddresses: Internal Servlet
Error:
> > > : java.lang.NullPointerException
> > > at org.gjt.mm.mysql.Statement.executeQuery(Statement.java)
> > > at org.gjt.mm.mysql.jdbc2.Statement.executeQuery(Statement.java:78)
> > > at UsefulAddresses.doGet(UsefulAddresses.java:50)
> > >
> > > If i enter the servlet URL in the address bar again press return it
> > returns
> > > to the error free page! Every time I refresh this page or any other of
my
> > > servlets I get this error. Could anyone please tell me why this is. My
> > > servlet code is the next email.
> > >
> > >
> >
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