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 [EMAIL PROTECTED] wrote:
> Date: Fri, 12 Jul 2002 13:56:38 -0400
> From: [EMAIL PROTECTED]
> Reply-To: Struts Users Mailing List <[EMAIL PROTECTED]>
> To: [EMAIL PROTECTED]
> 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:[EMAIL PROTECTED]]
> 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 <[EMAIL PROTECTED]>
> > Reply-To: Struts Users Mailing List <[EMAIL PROTECTED]>
> > To: Struts Users Mailing List <[EMAIL PROTECTED]>
> > Subject: Re: DynaBeans, DynaClass, DynaMen
> >
> > [EMAIL PROTECTED] 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
>
>
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