How to utilize custom annotations in MyBatis?

To use custom annotations in MyBatis, you first need to define an annotation and mark it where needed. Next, configure the corresponding handler in MyBatis configuration file so that MyBatis can recognize and process these custom annotations.

Here is a simple example:

Firstly, define a custom annotation.

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface MyAnnotation {
    String value();
}

Then annotate this custom annotation on the method in the Mapper interface.

public interface UserMapper {
    @MyAnnotation("getUserById")
    User getUserById(int id);
}

Next, configure the corresponding handler in the MyBatis configuration file.

<plugins>
    <plugin interceptor="org.apache.ibatis.plugin.AnnotationPlugin">
        <property name="annotation" value="com.example.MyAnnotation"/>
    </plugin>
</plugins>

This way, when MyBatis executes the methods in the Mapper interface, it will check if there is an @MyAnnotation annotation on the method. If there is, it will then execute the corresponding processing logic.