Bo-feng Java EE technical Articles--mybatis Mapper Resultmap (5) Constructor (Introduction resultmap label usage in constructor) __java

In Resultmap, the properties of a Java entity class are typically mapped to a field on a database table using the ID, result child element. But if you encounter JavaBean with only a parameter constructor, I also need to implement a JavaBean instantiation and data injection using the constructor element. Today, Beau Teacher will lead us to learn how to use the constructor element constructor in the Resultmap.

To continue with our previous user class, we add a constructor:

Accordingly, the RESULTMAP should make the following modifications:

MyBatis uses the parameter type to tag the constructor, injecting the result into the constructor. Java cannot get parameter names by firing, so when creating constructor elements, make sure that the parameters are passed sequentially and that the correct parameter types are specified.

The advantage of constructing method injection is to allow the value of a property to be set at initialization time without exposing the public method.

Idarg and ARG elements other properties and rules are the same as IDs, result properties: