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Message-ID: <20031212151733.8074.qmail@web60810.mail.yahoo.com>
Date: Fri, 12 Dec 2003 07:17:33 -0800 (PST)
From: David Graham <grahamdavid1980@yahoo.com>
Subject: Re: DBCP & DBUtils
To: Jakarta Commons Users List <commons-user@jakarta.apache.org>
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> 2. DBUtils - These sound real neat and I'd really like to use them, but 
> I can't find any decent documentation to get a beginner started. The 
> example page (http://jakarta.apache.org/commons/dbutils/examples.html) 
> may be enough to remind a developer how things work, but it's rough for 
> me because it leaves alot of questions and guessing.

I'll look at adding more examples soon but this is a community effort so
feel free to open a bugzilla enhancement ticket with a patch in cvs diff
-u format on the examples. 

Questions for different commons components should be sent in separate
emails with the component name prefixed on the subject line like [dbutils]
or [dbcp] so that people can filter messages accordingly.

David

> 
> I've used the JOCLPoolingDriverExample.java from DBCP as a basis for my 
> playing with the Utils. Following the directions on the example page, I 
> wasn't able to get it to work. Nor do I really understand the way its 
> supposed to work.
> 
> I gather the QueryRunner is designed to execute an sql query and give 
> you an object you define instead of a ResultSet. The example nor the 
> apis really tell you what the ResultSetHandler is doing. And what kind 
> of bean are you supposed to setup? I mean, if you do a SELECT * on some 
> table you can get alot of rows back, but with the QueryRunner you only 
> get a single object back. And I'm guessing you define that object 
> yourself. But, is that bean supposed to represent a row of the table 
> returned from your query? If it is, how do you access all of the rows. 
> Obviously, I'm confused and couldn't find anything to help. The only way
> 
> I got it to work was as follows:
> 
> import java.sql.DriverManager;
> import java.sql.Connection;
> import java.sql.Statement;
> import java.sql.ResultSet;
> import java.sql.SQLException;
> import java.util.ArrayList;
> import java.util.Iterator;
> 
> import org.apache.commons.dbutils.QueryRunner;
> import org.apache.commons.dbutils.ResultSetHandler;
> import org.apache.commons.dbutils.handlers.BeanHandler;
> 
> public class JOCLPoolingDriverExample {
> 
>     public static void main(String[] args) {
> 
>         Connection conn = null;
>         Statement stmt = null;
>         ResultSet rset = null;
> 
>         try {
>             System.out.println("Creating connection.");
>             conn = 
> DriverManager.getConnection("jdbc:apache:commons:dbcp:/db");
>            
>             QueryRunner runner = new QueryRunner();
>             ResultSetHandler h = new BeanHandler(OrderBean.class) {
>                 public Object handle(ResultSet rs) throws SQLException {
>                    
>                     //OrderBean orderBean = new OrderBean();
>                     ArrayList orders = new ArrayList();
>                    
>                     while(rs.next())
>                     {
>                         OrderBean orderBean = new OrderBean();
>                         orderBean.setOrderId(rs.getString(1));
>                         orderBean.setTotalAmount(rs.getString(2));
>                         orders.add(orderBean);
>                     }
> 
>                     return orders;
>                 }
>             };
>            
>             ArrayList p =
>                 (ArrayList)runner.query(conn, "SELECT ORDER_ID, 
> TOTAL_AMT FROM ORDERS", h);
>            
>             Iterator iter = p.iterator();
>             while(iter.hasNext())
>             {
>                 System.out.println((OrderBean)iter.next());
>             }
>         } catch(SQLException e) {
>             e.printStackTrace();
>         } finally {
>             try { rset.close(); } catch(Exception e) { }
>             try { stmt.close(); } catch(Exception e) { }
>             try { conn.close(); } catch(Exception e) { }
>         }
>     }
> }
> 
> 
> I doubt this is at all correct as its really not doing anything for me. 
> It's just as much work. From the example, it infers that the 
> ResultSetHandler class will work some magic in dumping your query into 
> an Object. Can anyone help?
> 
> Thanks,
> Mike Zatko
> 
> 
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