A Comprehensive Overview of MyBatis Architecture and Core Components

The author intends to give a global perspective on MyBatis, summarizing its overall architecture to help readers understand the framework more thoroughly.

Key features of MyBatis include:

SQL mapping configuration using XML or annotations to separate SQL statements from Java code.

Dynamic SQL generation for flexible query building.

Parameter mapping that automatically binds Java object properties to SQL parameters.

Result set mapping that converts query results into Java objects.

Transaction management integrated with frameworks like Spring to ensure atomicity.

Connection‑pool integration (e.g., Apache DBCP , C3P0 , HikariCP ) for efficient resource handling.

Second‑level cache for sharing data across sessions.

The MyBatis architecture is divided into three layers: the foundation support layer , the core processing layer , and the interface layer . The foundation layer handles resource loading and configuration parsing, the core layer manages SQL execution and transaction handling, and the interface layer provides mapper proxies.

Configuration file parsing is performed by classes inheriting from BaseBuilder :

XMLStatementBuilder parses <select> , <insert> , <update> , <delete> tags and builds MappedStatement objects.

XMLMapperBuilder parses mapper XML files ( Mapper.xml ) and constructs mapping metadata.

XMLConfigBuilder parses the main configuration file ( mybatis-config.xml ) to build the global Configuration object.

During proxy construction , SqlSession.getMapper creates a dynamic proxy via MapperProxyFactory , MapperRegistry , and MapperProxy , linking mapper interfaces to SQL statements.

The SQL execution flow involves:

Creating a Statement / PreparedStatement / CallableStatement via the SqlSession .

Executing the SQL query.

Processing the ResultSet and mapping results back to Java objects.

Finally, the article recaps the complete process: building a SqlSessionFactory , opening a SqlSession , executing SQL via methods like selectOne() , selectList() , insert() , update() , delete() , parsing dynamic SQL, and handling results.