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From Pawan Singh <pa...@pinger.org>
Subject How to use DBCP in J2SE environment
Date Mon, 14 Dec 2009 05:45:54 GMT
Hi

Can someone with Apache DBCP expertise clarify this question? This code snippet assumes that
Database connection pools have been established using Apache DBCP package.

public ResultSet getResults(String sql)
{

           Connection conn = pooledDataSource.getConnection();   <-- gets connection from
pool
           PreparedStatement stmt = conn.prepareStatement(sql,...);
           ResultSet rs = stmt.executeQuery();
           conn.close(); <--- return to pool
           return rs;
}

public uicode_in_someotherproject() {
	ResultSet rs  = getResults("SELECT * from foo");
        bindDataToTableControl(rs);
}

My problem is simply controlling the lifetime of the ResultSet. Since it is a J2SE app, and
we return ResultSet back to the user interface to bind data to user controls, I cannot close
the connection. This is because PoolableConnection actually "passivates" the connection on
returning to pool which closes the statement and result set.

My only other choice is to make the top layer control the lifetime of connection and statement
- but that is ugly. I though that DBCP's connection pool will simply return the connection
without "passivating" it and therefore everything will work properly.

I just want advice from experts on how to control the lifetime of ResultSet. Do I have to
keep a reference to connection object till I am ready to discard ResultSet?

Another question is related to "garbage collection". Why does DBCP not use "finalize" to return
these connections and statements back to pool? It would seem to me that it will solve some
of the problems related to having to call "close" on all these objects properly - otherwise
one can cause a leak.

-Pawan
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