I think that it is bad practice to to database connection inside the jsp
page. Make a seperate bean or different class that handles the
connection will help you in long run.
-Original Message-
From: Thorbjørn Ravn Andersen (Scandiatransplant)
[mailto:[EMAIL PROTECTED]]
Sent: Tuesday, January 29, 2002 10:14 AM
To: [EMAIL PROTECTED]
Subject: Struts DataSource object - how much can be taken for given?
I have now progressed further, and run into a few questions which I
would
appreciate help with in order to be nudged in the right direction.
After a bit of work with the Struts basic JDBC-connection pooling system
and the struts-config.xml file, I found out that I can get access to my
database from a JSP as follows:
%@ page
import=javax.servlet.*,javax.sql.*,java.sql.*,org.apache.struts.*,org.a
pache.struts.action.* %
%
DataSource dataSource = (DataSource)
getServletContext().getAttribute(Action.DATA_SOURCE_KEY);
Connection conn = dataSource.getConnection();
Statement s = conn.createStatement();
ResultSet rs = s.executeQuery( select count(*) from recipient);
...
I want to do this in order to provide a set of JSP-pages which test
basic
functionality without requiring the whole MVC-system to be functional.
I have written a couple of beans, each of which are to correspond to a
given database table (not much new in that), where they will synchronize
over a Connection-object, and I would like to know how
I should design this for it to be so generic as possible. The existing
database scheme we are building this application on top, consists of
several hundred tables, so I must recycle resources.
Can I expect that the DataSource object will be the same in the lifetime
of my application (a given bean will only talk to a single database, and
we will most likely not use more than a single database for the whole
application), or should I look in getServletContext() each time I need a
new Connection?
I understand that for connection pools to work correctly I should close
my
connection when I am done with it, and request a new one next time.
Will
the above code allow me to choose connection pool managers freely
(provided that it is running correctly), or is this just for the one
provided by Struts?
I have a strong feeling that I should refrain as much as possible from
scriplets in the JSP, so I would also appreciate knowing if there are
beans or taglibs that help manage such an object. My own beans will be
able to accept the appropriate object (DataSource etc) as a property,
but
are there any facilities that help providing what I need as a property?
And a last question. As part of the work flow of the users they may
have
to be presented to a rather long list of persons. I have considered
whether it would be feasible ressourcewise to simply build an ArrayList
of
Beans, where each bean corresponds to a person in the database, and then
have it as a session property. This also goes very well with the
display:table taglib. Should I go for a database request per subtable,
and do it all by my self? I would appreciate comments from people who
have tried this, and have experiences to share.
Some of the tables have many fields, and may be rather large objects.
We
can expect few users, and few simultaneous searches.
If I have missed a FAQ where this is explained in detail, I apologize.
I
am still struggling with learning the framework, and I have tried to
follow and read most of the documentation and the links it contains.
Best Regards,
--
Thorbjørn Ravn Andersen
Scandiatransplant, c/o Christian Mondrup
89 49 53 01
http://biobase.dk/~tra
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