What is the principle behind MyBatis result set mapping?
MyBatis utilizes XML configuration files or annotations to map query results to Java objects. The principle of result set mapping involves defining mapping rules that match the columns in the query result with the properties in the Java objects, thereby converting the query result into Java objects.
MyBatis offers two options for defining rules to map result sets.
- XML configuration file: Mapping rules are defined using tags in the XML configuration file. Columns from query results can be mapped to properties in Java objects using tags, and mapping of associated query results can be done using tags.
- Explanation: Mapping rules can be defined by using the @Result annotation on the properties of Java objects. The @Result annotation can be used to map columns in query results to properties in Java objects, as well as to map associated query results using the @One or @Many annotations.
When executing a query, MyBatis will map each row of the query result according to the defined mapping rules to a corresponding Java object. If there are multiple rows in the query result, MyBatis will map each row to a Java object and return these objects in a List or an array.
In summary, the principle of result set mapping in MyBatis is to match the columns in the query result with the properties in Java objects based on defined mapping rules, thereby converting the query result into Java objects.