@MapperScan And @Mapper

• @MapperScan And @Mapper
  • The background that
  • @MapperScan And @Mapper The role of
  • adopt @Mapper Give Way Mybatis Provide proxy implementation for interface
  • adopt @MapperScan Give Way Mybatis Provide proxy implementation for interface

The background that

We're writing mapper when , You only need to write the interface without implementing it , from Mybatis The framework provides the corresponding proxy implementation class for the interface （, And register the proxy implementation class into the container ）. however Mybatis How do you know which interfaces need to be proxy implemented , It is through @MapperScan And @Mapper Notes to know .

@MapperScan And @Mapper The role of

send Mybatis Know which interfaces need to be provided with proxy implementation .

adopt @Mapper Give Way Mybatis Provide proxy implementation for interface

Statement ： Different versions mybatis There may be differences in the generation mechanism of proxy classes , The following conclusion @MapperScan be based on org.mybatis:mybatis-spring:2.0.6,@Mapper be based on org.mybatis:mybatis:3.5.9

1. Use... On the target interface @Mapper Note to identify

2. Ensure that the source code of the interface must be under the current project

   namely ： The interface must be the source code interface of the current project , It cannot be in other dependent class libraries , No @Mapper Will not enter into force .

   notes ： One might think that using @ComponentScan Other dependent classes in the library mapper Import is OK . In fact, it can't be ,@ComponentScan What is being scanned @Component Wait for the annotation to mark the class and register it in Spring Containers , And Mybatis The recognition mechanism of scanning generation agent class is two concepts .

   notes ： If you need to Mybatis For other dependent class libraries mapper Interface also generates proxy classes , Then please use @MapperScan

adopt @MapperScan Give Way Mybatis Provide proxy implementation for interface

Statement ： Different versions mybatis There may be differences in the generation mechanism of proxy classes , The following conclusion @MapperScan be based on org.mybatis:mybatis-spring:2.0.6,@Mapper be based on org.mybatis:mybatis:3.5.9

1. You just need to specify the range you want .Mybatis The corresponding proxy implementation will be carried out for all interfaces under this scope （, And register the proxy implementation class into the container ）.

   notes ： The scope can include the scope within the current project , You can also include the scope of the class library that the current project depends on .

   notes ：@MapperScan All interfaces within the specified scope , All interfaces , Whether it's mapper Interface 、 still service Interface 、 Or some other interface , As long as the interface is @MapperScan Within the specified range ,Mybatis Will implement the corresponding proxy for this interface （, And register the proxy implementation class into the container ）. therefore In the use of @MapperScan when , It must be noted that the specified range cannot be too large . Avoid the following ：
   

Related information

• This article has been included in 《 Programmer growth notes 》 , The author JustryDeng