Add support for JdbcTempalte.queryForObject(sql,<primitive>.class)

[rwinch]

Previously using jdbcTemplate.queryForObject(sql, int.class) produced
a TypeMismatchDataAccessException stating it could not convert an Integer
to an int.

This update allows conversion to the respective primitives instead of just
the wrapper Objects.

Issue: SPR-13220

[panchenko]

Wouldn't it be simpler to convert primitive class to the corresponding wrapper initially (when initializing SingleColumnRowMapper#requiredType) ?

[rwinch]

@panchenko Thanks for your feedback. If I understand the question correctly, you wonder why we don't just convert the value in the constructor and / or setter? If so

• NumberUtils.convertNumberToTargetClass(Number, Class<T>) is used in multiple places (and may be used in more places in the future), so I think that is the correct place to fix this.
• convertValueToRequiredType(Object,Class<?>) which should work for primitive values as well For example, while mapRow passes in this.requiredType, the class SingleColumnRowMapper is non final so anyone that extends the class can pass in a different type to the method.
• As far as I know there is no easy way to convert from the primitive class to its corresponding wrapper class, so this actually involves quite a bit of code.

Does this help? If not, can you please clarify? Perhaps I am not understanding your proposal.