struts-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Craig R. McClanahan" <craig...@apache.org>
Subject RE: DynaBeans, DynaClass, DynaMen
Date Fri, 12 Jul 2002 22:45:20 GMT
I implemented something a little more memory-efficient than this (doesn't
require the entire result set to be in memory) in tonight's nightly build
of commons-beanutils, which will therefore be available in the 20020713
nightly build of Struts.  You use it something like this:

  Connection conn = ...;
  Statement stmt = conn.createStatement();
  ResultSet rs = stmt.executeQuery("select * from customers");
  Iterator rows = (new ResultSetDynaClass(rs)).iterator();
  while (rows.hasNext()) {
    DynaBean row = (DynaBean) rows.next();
    System.out.println("Processing customer " + row.get("account_id"));
    ... access this row as a DynaBean ...
  }
  rs.close();
  stmt.close();

I elected to avoid doing the type conversions, so the properties you get
back will correspond to their types in the database.

Craig


On Fri, 12 Jul 2002 wbchmura@Ensign-BickfordInd.com wrote:

> Date: Fri, 12 Jul 2002 13:56:38 -0400
> From: wbchmura@Ensign-BickfordInd.com
> Reply-To: Struts Users Mailing List <struts-user@jakarta.apache.org>
> To: struts-user@jakarta.apache.org
> Subject: RE: DynaBeans, DynaClass, DynaMen
>
>
>
> Here is what I am using...  Very simple and only returns strings...
>
>
>   /**
>     * Converts a resultset into an ArrayList of DynaBeans
>     *
>     * @param resultSet SQL result set to be converted
>     * @return ArrayList of DynaBeans with all columnnames converted to
>     *         lowercase
>     * @throws SQLException DOCUMENT ME!
>     */
>    private static ArrayList getDynaBeanArrayList(ResultSet resultSet)
>                                           throws SQLException {
>
>       ResultSetMetaData metaData = resultSet.getMetaData();
>       int cols = metaData.getColumnCount();
>       ArrayList list = new ArrayList();
>       DynaProperty[] props = new DynaProperty[cols];
>       BasicDynaClass dClass = null;
>
>       for (int i = 1; i <= cols; i++) {
>          props[i - 1] = new
> DynaProperty(metaData.getColumnName(i).toLowerCase());
>       }
>
>       try {
>          dClass = new BasicDynaClass("test",
>                                      Class.forName(
>
> "org.apache.commons.beanutils.BasicDynaBean"),
>                                      props);
>       } catch (Exception e) {
>          e.printStackTrace();
>       }
>
>       while (resultSet.next()) {
>
>          HashMap map = new HashMap(cols, 1);
>
>          for (int i = 1; i <= cols; i++) {
>             map.put(metaData.getColumnName(i).toLowerCase(),
>                     resultSet.getString(i));
>          }
>
>          try {
>
>             DynaBean dbean = dClass.newInstance();
>             BeanUtils.populate(dbean, map);
>             list.add(dbean);
>          } catch (Exception e) {
>             e.printStackTrace();
>             throw new SQLException("RequestUtils.getArrayList: "
>                                    + e.toString());
>          }
>       } // End While
>
>       return (list);
>    }
>
>
> -----Original Message-----
> From: craigmcc [mailto:craigmcc@apache.org]
> Sent: Friday, July 12, 2002 12:07 PM
> To: struts-user
> Subject: Re: DynaBeans, DynaClass, DynaMen
>
>
>
>
> On Fri, 12 Jul 2002, Thorbjoern Ravn Andersen wrote:
>
> > Date: Fri, 12 Jul 2002 07:02:57 +0200
> > From: Thorbjoern Ravn Andersen <tra@biobase.dk>
> > Reply-To: Struts Users Mailing List <struts-user@jakarta.apache.org>
> > To: Struts Users Mailing List <struts-user@jakarta.apache.org>
> > Subject: Re: DynaBeans, DynaClass, DynaMen
> >
> > wbchmura@Ensign-BickfordInd.com skrev:
> >
> > >...anyone remember DynaMen?
> > >
> > >Anyhow...  I got a Dynabean mechanism working that builds a DynaBean
> > >based on the metadata of a SQL result set, populates and array of the
> > >little buggers and passes it back to me.  For displaying I have a tag
> > >library that does not like a call to get('name') as the field name.
> > >What is the best way to get around this?
> > >
> > I wrote an AnonyBeans package which uses BCEL to generate beans on the
> > fly based on a ResultSet.  It is alpha code but works for me, and is
> > usable anywhere where you need a real traditional bean, but where you
> do
> > not want to serialize it or  use its type in Java source.
> >
> > Is this interesting?
> >
>
> I think it would be  interestesting, even though it might not be
> universally useful (some containers won't let you introduce new classes
> at
> runtime).
>
> I'd also be interested in a mechanism that converted a ResultSet into a
> custom DynaClass, with a corresponding DynaBean for each row.  This
> would
> be trivially simple to do -- so simple that it probably makes a
> worthwhile
> addition to commons-beanutils itself if someone wanted to take this on.
>
> This wouldn't help you create dynamic input forms, but it would make a
> completely flexible bean-like wrapper around a result set so you can use
> Struts tags to display stuff.
>
> > --
> >   Thorbjørn Ravn Andersen                 http://biobase.dk/~tra
>
> Craig
>
>
> --
> To unsubscribe, e-mail:
> <mailto:struts-user-unsubscribe@jakarta.apache.org>
> For additional commands, e-mail:
> <mailto:struts-user-help@jakarta.apache.org>
>
>
>
> --
> To unsubscribe, e-mail:   <mailto:struts-user-unsubscribe@jakarta.apache.org>
> For additional commands, e-mail: <mailto:struts-user-help@jakarta.apache.org>
>
>


--
To unsubscribe, e-mail:   <mailto:struts-user-unsubscribe@jakarta.apache.org>
For additional commands, e-mail: <mailto:struts-user-help@jakarta.apache.org>


Mime
View raw message