commons-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Dan Fabulich (JIRA)" <j...@apache.org>
Subject [jira] Issue Comment Edited: (DBUTILS-48) Maintaining a parallel Java 1.5 version of DButils
Date Thu, 05 Feb 2009 16:31:59 GMT

    [ https://issues.apache.org/jira/browse/DBUTILS-48?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12670809#action_12670809
] 

dfabulich edited comment on DBUTILS-48 at 2/5/09 8:30 AM:
-------------------------------------------------------------

Here's a patch to update DbUtils for 1.5.  It's backwards-compatible with the old API; in
fact, most of my changes are type-erased at compile time.

The biggest change was to change the order of the QueryRunner.query method signatures (var-args
have to go at the end).  The old functions are left in, but deprecated.

I also added a helper static method ResultSetIterator.iterable, which returns an Iterable,
for use in for-each loops.  You'd use it like this:

{code}
for (Object[] row : ResultSetIterator.iterable(resultSet)) {
  // do stuff
}
{code}

      was (Author: dfabulich):
    Here's a patch to update DbUtils for 1.5.  It's backwards-compatible with the old API;
in fact, most of my changes are type-erased at compile time.

The biggest change was to change the order of the QueryRunner.query method signatures (var-args
have to go at the end).  The old functions are left in, but deprecated.

I also added a helper static method ResultSetIterator.iterable, which returns an Iterable,
for use in for-each loops.  You'd use it like this:

for (Object[] row : ResultSetIterator.iterable(resultSet) {
  // do stuff
}
  
> Maintaining a parallel Java 1.5 version of DButils
> --------------------------------------------------
>
>                 Key: DBUTILS-48
>                 URL: https://issues.apache.org/jira/browse/DBUTILS-48
>             Project: Commons DbUtils
>          Issue Type: New Feature
>            Reporter: Olivier Grégoire
>            Priority: Minor
>             Fix For: 1.2
>
>         Attachments: generics.patch
>
>
> Well, DButils was a great step forward when managing a database. But Java 5 came and
added a lot of new features to the language, including generics, which I think is easy to
put in place.
> The base change of all this is changing the signature of ResultSetHandler:
> public interface ResultSetHandler<T> {
>   public T handle(ResultSet rs) throws SQLException;
> }
> With this code, we can easily provide directly from the QueryRunner a specific object
without having to cast it.
> Furthermore, we can also make the queries much more efficient, and declare only 2 method
instead of three as it is currently the case:
> 	public <T> T query(String sql, ResultSetHandler<T> handler, Object... params)
throws SQLException {
> 		Connection connection = this.prepareConnection();
> 		try {
> 			return this.query(connection, sql, handler, params);
> 		} finally {
> 			close(connection);
> 		}
> 	}
> 	public <T> T query(Connection connection, String sql, ResultSetHandler<T>
handler, Object... params) throws SQLException {
> 		PreparedStatement statement = null;
> 		ResultSet resultSet = null;
> 		try {
> 			statement = this.prepareStatement(connection, sql);
> 			this.fillStatement(statement, params);
> 			resultSet = this.wrap(statement.executeQuery());
> 			return handler.handle(resultSet);
> 		} catch (SQLException e) {
> 			throw this.nestException(e, sql, params); // nestException creates an exception to
be thrown here, instead of rethrow(e, sql, params);
> 		} finally {
> 			try {
> 				close(resultSet);
> 			} finally {
> 				close(statement);
> 			}
> 		}
> 	}
> I don't know for you, but I find that code much more readable and maintainable. In fact,
I already did this implementation and use it in prod without any issue, since it is only basic
language adaptation.
> And using it is also very easy:
> Book book = queryRunner.query("SELECT * FROM book WHERE title = ? AND author = ?", new
BeanHandler(Book.class), title, author);
> instead of 
> Book book = (Book)queryRunner.query("SELECT * FROM book WHERE title = ? AND author =
?", new BeanHandler(Book.class), new Object[]{title, author});
> However, I wrote an original time estimation of 1 day, because all classes have to be
adapted, especially those included in org.apache.common.dbutils.handlers.
> As I estimate, it is minor, it is just a request in order to have more beautiful code,
for a downside of providing a Java 1.5 compatible version of DBUtils. Maintaining this should
be very rough as well, since DBUtils is not really big (but it's amazing how so little code
can provide so much code improvements!)

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message