How can I pass multiple parameters and use them?

问题:

Hi I'm new to myBatis.

I'm using MyBatis and Spring with mybatis-spring.

How can I pass two different types of objects as parameters, and how can I use their properties in query?

<update id="update" parameterType="A, B"> <!-- @@? -->
  UPDATE SOME WHERE x=A.x AND y=B.y <!-- @@? -->
</update>

回答1:

Do not specify parameterType but use @Param annotation on parameters in mapper:

@Mapper
public interface MyMapper {

    void update(@Param("a") A a, @Param("b") B b);

    ...
}

Then reference them in mapping:

<update id="update" > 
   UPDATE SOME WHERE x=#{a.x} AND y=#{b.y}
</update>

回答2:

Use parameterType="map" and @Param annotation.

Method declared in interface:

void mapCategoryAndPage(@Param("categoryLocalId") Long categoryLocalId, @Param("pageLocalId") Long localId);

It is not required that value of @Param annotation must be equal to name of parameter

<insert id="mapCategoryAndPage" parameterType="map">
    INSERT INTO
        category_page_mapping (
            page_local_id,
            category_local_id)
    VALUES
        (#{pageLocalId},
         #{categoryLocalId});
</insert>

回答3:

I would suggest reading the MyBatis documentation - it is pretty comprehensive and accurate.

Lets take an example: updating a customer's name from a com.mycompany.Customer POJO instance, which has a getFirstName() getter.

1. Pass an instance of your Customer class as the parameter
2. Set the parameterType= "com.mycompany.Customer". But check out the alias facility - then you can use the shorthand version parameterType="Customer"
3. Use the standard MyBatis syntax in the SQL: ... set FIRST_NAME = #{firstName}

(Edit) If you need to pass multiple objects there are various options:

1. Pass a map containing the multiple objects
2. Create a utility class the aggregates your multiple classes, and pass this as the parameter.

Again, please read the manual...