题记：
“低碳从拔下插头做起”，开源，从关注产品社区做起：）
发这个贴的的缘由是看了jnn大哥发的一篇关于开源软件的帖子http://www.iteye.com/topic/277696，虽然是08年写的，但里面说到follow社区的mail list的建议是不错的，想想自己还未奉献过代码，于是去ibaits的google社区瞅了一眼，其实只要你行动，提交一个被accepted的issue并不是那么困难。
以下就是展现一个最新被ibatis3.x接受的建议。（当然不是我commit的，希望以后有机会吧）
Reported by clinton.begin, May 17, 2010
Reporter: Travis Hein
Would it be possible to create a new annotation (or does one exist already
and I just have not found it yet), where I can specify that @Select results
should be a
可以不可以为@select新增一个注解用于重用resultMap配置中定义的map。
For example,
比如：
Consider a "country" table,
CREATE TABLE COUNTRY ( ID bigint PRIMARY KEY NOT NULL, CODE varchar(2) NOT NULL, ISO_CODE varchar(3) NOT NULL, NAME varchar(2147483647), COUNTRY_CODE varchar(10), ACTIVE boolean DEFAULT TRUE NOT NULL );
And the java Bean,
public class Country {
Long id;
String code; // 2 digit ISO country code
String isoCode; // 3 digit ISO country code
String name; // string name
String countryCode; // the telephone dialing prefix (e.g. +1)
boolean active = true;
// and all the get() set() methods for these bean properties
}
And then the mapper interface,
public interface CountryDAO {
/**
* Selects all country entries.
* Though it appears when we use the annotations, we need to specify the
results every time ?
*/
@Select( value = { "select * from country where active = true" })
@Results(value = {
@Result(property="id"),
@Result(property="code"),
@Result(property="isoCode", column="iso_code"),
@Result(property="name", column="name"),
@Result(property="countryCode", column="country_code"),
@Result(property="active", column="active")
})
List getAllActive();
// TODO: all these methods would also be select queries, where I would
want the same results map as above
Country getById(Long id);
Country getByCode(String code);
Country getByIsoCode(String isoCode);
}
这里每个方法都需要重复添加如上返回的map定义，就显的很冗余了。
Where, instead of the @Results annotation, which would need to be
duplicated with its nested @Result annotations on every select method that
I want to return the same mapping, what I would wish to have would be
something like a
@ResultMap(value="myMapperID") 作者想添加这个注解，替代上面的重复定义。
annotation, where the myMapperID would be the ID of a
declared in the mapper's xml file that will be included by the
SqlMapConfig.xml (which I have anyway to bind to this mapper interface, and
also because I have some more complex queries declared in the xml mapper
file too).
Where in this example, I already have a
So this wishful @ResultMap annotation would then make the mapper interface
look like:
修改后的代码变为：
public interface CountryDAO {
@Select( value = { "select * from country where active = true" })
@ResultMap(value = "countryResult")
List getAllActive();
// and now other things that want to select into this map can do so,
re-using the single map declaration
// that is referenced in the xml.
@Select( value = { "select * from country where id = #{id} })
@ResultMap(value = "countryResult")
Country getById(Long id);
@Select( value = { "select * from country where code = #{code} })
@ResultMap(value = "countryResult")
Country getByCode(String code);
@Select( value = { "select * from country where isoCode = #{isoCode} })
@ResultMap(value = "countryResult")
Country getByIsoCode(String isoCode);
}
I think having something like this @ResultMap annotation would be a good
thing to have, what do you think?
看到countryResult这个map已经在xml文件中定义好了，无需再每个方法前面重复定义了，只要声明就ok了。