Well, I too thought about this...
Then I thought, If I leave the getConnection() open and let the DAO take
care of it, I thought the same DAO can be used for multiple datasources. The
way you get a connection does not matter.
Well, I am still 50/50 about this idea though. I am thinking of another
approach
Lets say I have an abstract class DAOFactory.(A factory that creates DAO's)
so now My ABCDaofactory extends DAOFactory. (ABCDaoFactory is a singleton)
In ABCDaoFactory, i write an init method which sets the connection
Manager(It could be an Oracle manager or a DB2Connection manager).
Also, the ABCDaofactory has a method getMyBottleOfPicklesDao() which
returns MyBottleOfPicklesDao (A data access object).
This factory would get you a ready made DAO and all you got to do is use
it.(Bruce Eckel calls these people who use these as Client Developers Hee
ha!!)
The MyBottleOfPicklesDao would extend a BAseDAO which has a concrete (not
abstract) getConnection method which says
abstract class BaseDAO
getConnection()
{
// This way you delegete the getConnection in the base class and that
connection depends on the Connection Manager //which is another layer of
abstraction that is set in the ABCDaoFactory.
conn = connectionManager.getConnection();// the connectionManager
variable is set in the factory
}
this way your DAo doesnt need to know how to get a connection
regards
pathangi r
-----Original Message-----
From: Geddes, Mark (ANTS) [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, July 18, 2001 9:39 AM
To: '[EMAIL PROTECTED]'
Subject: RE: Where do YOU put JDBC calls?
This is a nice pattern, but I do not want my DAO to be responsible for
getting the connection. I need to use them in the web-tier (no EJBs) and
possibly also the middle tier. In each case the DataSource may be obtained
in a different manner and it is not the DAO's responsibility to know how.
mark
-----Original Message-----
From: Pathangi, Rao H. [mailto:[EMAIL PROTECTED]]
Sent: 18 July 2001 15:33
To: '[EMAIL PROTECTED]'
Subject: RE: Where do YOU put JDBC calls?
Mark
To handle this situation, I wrote a base class which has the connection
Object as a protected variable. Lets say you have a method readOrder(String
orderId)..
Write another abstract method getConnection() in your BaseDAO. Use
connection manager or pooling or whatever, but get a connection in this
method and implement it in your DAo that extends the BaseDAo
Now in the method readOrder can read something like this
readOrder(String OrderId)
{
try
{
Connection con = getConnection(); // Your DAO is now plugged
// Do something with the connection...
}
catch{}
finally
{
//close connection, unplug your DAO
}
}
Hope that helps
pathangi r
-----Original Message-----
From: Geddes, Mark (ANTS) [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, July 18, 2001 9:23 AM
To: '[EMAIL PROTECTED]'
Subject: RE: Where do YOU put JDBC calls?
ditto.
I am always reading that the Connection reference should be passed into the
method. After writing a few DAOs in this manner, I found the exception
handling too tedious - I was checking for closed connections both within the
DAO method and also in the calling method. So I usually pass in a DataSource
and ensure that my DAO method obtains and closes the connection. Shoot me
down if you like.
Mark
-----Original Message-----
From: Pathangi, Rao H. [mailto:[EMAIL PROTECTED]]
Sent: 18 July 2001 15:18
To: '[EMAIL PROTECTED]'
Subject: RE: Where do YOU put JDBC calls?
Iam using the DAO(Data Access Object) design pattern for such Data access
situations. DAO is a layer of abstraction that works in conjunction with the
Business Object which is nothing but a container for business data. the
Business Object calls the DAO's business methods. The DAO's Business methods
wrap the JDBC Code for data base interaction. Its been explained clearly on
the J2EE blueprints section.Once you are done writing your DAO's, extend the
DAO into a session bean or use it seperately.
regards
pathangi r
-----Original Message-----
From: Ryan Cornia [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, July 18, 2001 8:56 AM
To: [EMAIL PROTECTED]
Subject: Where do YOU put JDBC calls?
I'm wondering what people are considering best practices for JDBC calls?
I have been writing beans that wrap a database table, and include functions
"select", "insert", "delete". These functions either load the bean, insert
the bean values in the database, or delete the record from the database. In
all of these functions, I pass in a database connection from the action. (Or
whatever else is calling the bean.)
ie- public boolean select(Connection cn1, String primaryKey)
How are others doing it? I think this is a good approach, but want to see if
someone has come up with something better.
Thanks,
Ryan
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