The use of @ Mapper and @ MapperScan in mybatis annotations

Directory mybatis Annotation @ Mapper and @ MapperScan Mode 1: Use @ Mapper Annotation Mode 2: Use @ MapperScan Annotation @ MapperScan and @ Mapper Difference and Understanding Function Scan One Package Scan Multiple Packages

mybatis annotations @ Mapper and @ MapperScan

When using the Mybatis persistence layer framework to manipulate the database, we can use the @ Mapper annotation and the @ MapperScan annotation to hand over the Mapper interface class to Sprinig for management.

Mode 1: Use @ Mapper annotations

Advantages: finer granularity

Disadvantages: Adding @ Mapper annotation in Mapper interface class directly, it is necessary to add @ Mapper annotation in every mapper interface class, which is cumbersome

Mode 2: Use @ MapperScan annotations

With @ MapperScan, you can specify the packet path of the Mapper interface class to be scanned

@SpringBootApplication  
@MapperScan("com.erayt.mapper")  
public class App {  
    public static void main(String[] args) {  
       SpringApplication.run(App.class, args);  
    }  
}  

You can use * as a wildcard in the path to match the package name

@SpringBootApplication  
@MapperScan("com.erayt.*.mapper")  
public class App {  
    public static void main(String[] args) {  
       SpringApplication.run(App.class, args);  
    }  
}  

You can also scan multiple packages using @ MapperScan annotations

@SpringBootApplication  
@MapperScan("com.erayt.mapperFirst","com.erayt.mapperSecond")  
public class App {  
    public static void main(String[] args) {  
       SpringApplication.run(App.class, args);  
    }  
}  

Difference and understanding between @ MapperScan and @ Mapper

Action

Scan the Dao layer in the project, inject dao interface class into Spring, and let other classes refer to it;

@Mapper In the dao interface class, add this annotation; The trouble is that every dao interface class must add this annotation; @MapperScan You can specify the path of the dao interface class to be scanned, and you can add this annotation to the startup class instead of @ Mapper annotation. (You don't need to add @ Mapper annotation to all dao interface classes in this module.)

Scan 1 packet

@MapperScan("com.demo.mapper") Scanning the interface in the specified package @MapperScan("com.demo.*.mapper") : 1 * represents a level 1 package; For example, you can scan com. demo. aaa. mapper, but you cannot scan com. demo. aaa. bbb. mapper @MapperScan("com.demo.**.mapper") Two * for any package; For example, you can scan com. demo. aaa. mapper, or you can scan com. demo. aaa. bbb. mapper

Scan multiple packets

If the dao interface class is under a package or sub-package that the main program can scan:

@MapperScan({"com.kfit.demo","com.kfit.user"}) 

If not, you can configure it as follows:

@MapperScan({"com.kfit.*.mapper","org.kfit.*.mapper"})