Maintaining a parallel Java 1.5 version of DButils
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Key: DBUTILS-48
URL: https://issues.apache.org/jira/browse/DBUTILS-48
Project: Commons DbUtils
Issue Type: New Feature
Reporter: Olivier Grégoire
Priority: Minor
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!)
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