題記：
“低碳從拔下插頭做起”，開源，從關注產品社區做起：）
發這個貼的的緣由是看了jnn大哥發的一篇關於開源軟件的帖子http://www.iteye.com/topic/277696，雖然是08年寫的，但裏面說到follow社區的mail list的建議是不錯的，想想自己還未奉獻過代碼，於是去ibaits的google社區瞅了一眼，其實只要你行動，提交一個被accepted的issue並不是那麼困難。
以下就是展現一個最新被ibatis3.x接受的建議。（當然不是我commit的，希望以後有機會吧）
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 <resultMap> that exists in the mapper XML file ?
可以不可以爲@select新增一個註解用於重用resultMap配置中定義的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<Country> 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);
}
這裏每個方法都需要重複添加如上返回的map定義，就顯的很冗餘了。
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") 作者想添加這個註解，替代上面的重複定義。
annotation, where the myMapperID would be the ID of a <resultMap> I have
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
<mapper namespace="CountryDAO">
<resultMap type="Country" id="countryResult">
<result property="id" column="id"/>
<result property="code" column="code"/>
<result property="isoCode" column="iso_code"/>
<result property="name" column="name"/>
<result property="countryCode" column="country_code"/>
<result property="active" column="active"/>
</resultMap>
So this wishful @ResultMap annotation would then make the mapper interface
look like:
修改後的代碼變爲：
public interface CountryDAO {
@Select( value = { "select * from country where active = true" })
@ResultMap(value = "countryResult")
List<Country> 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這個map已經在xml文件中定義好了，無需再每個方法前面重複定義了，只要聲明就ok了。