Design Patterns Employed in the MyBatis Framework

MyBatis, an ORM framework with more than twenty thousand lines of source code, leverages a wide range of design patterns to decouple complex scenarios, making the framework’s architecture both flexible and maintainable.

Creational patterns include the Factory pattern (e.g., SqlSessionFactory creation), the Singleton pattern (e.g., the global Configuration object), and the Builder pattern (e.g., ResultMapBuilder for constructing complex mapping objects). These patterns simplify object creation and configuration within MyBatis.

Structural patterns are illustrated by the Adapter pattern (unifying various logging frameworks under a common interface), the Proxy pattern (the MapperProxy that provides dynamic DAO implementations), the Composite pattern (the SqlNode tree that represents hierarchical SQL fragments), and the Decorator pattern (the second‑level cache decorator that wraps a simple executor).

Behavioral patterns appear as the Template method (the abstract BaseExecutor defines a fixed execution workflow), the Strategy pattern (different TypeHandler implementations select algorithms for handling various JDBC types), and the Iterator pattern (the PropertyTokenizer traverses nested property expressions). Each pattern isolates variable behavior while preserving a stable overall process.

In total, MyBatis employs roughly ten distinct design patterns, demonstrating how a sophisticated ORM framework can systematically address complexity through proven architectural solutions, and highlighting the value of studying such source code for deeper understanding of backend system design.