Spring Architecture Series-5.Implementing Mybatis Integration

Introduction MyBatis is a popular persistence framework that provides a flexible way to map SQL statements to Java objects.In this article, I'll explore how to implements MyBatis integration in aSpring-like framework,base on my miniSpring project's implementation. Core Components The MyBatis integration consists of several key components: src/com/yaruyng/batis/ ├── DefaultSqlSessionFactory.java ├── DefaultSqlSession.java ├── SqlSessionFactory.java ├── SqlSession.java └── MapperNode.java SqlSessionFactory Implementation The SqlSessionFactory is the entry point for creating SqlSession instance: public class DefaultSqlSessionFactory implements SqlSessionFactory { @Autowired JdbcTemplate jdbcTemplate; String mapperLocations; Map mapperNodeMap = new HashMap(); public void init() { scanLocation(this.mapperLocations); // Initialize mapper nodes } @Override public SqlSession openSession() { SqlSession newSqlSession = new DefaultSqlSession(); newSqlSession.setJdbcTemplate(jdbcTemplate); newSqlSession.setSqlSessionFactory(this); return newSqlSession; } } key features: Integration with Spring's IoC container Mapper XML file scanning Session management Mapper XML Parsing The framework parse MyBatis mapper XML files: private Map buildMapperNodes(String filePath) { SAXReader saxReader = new SAXReader(); URL xmlPath = this.getClass().getClassLoader().getResource(filePath); try { Document document = saxReader.read(xmlPath); Element rootElement = document.getRootElement(); String namespace = rootElement.attributeValue("namespace"); Iterator nodes = rootElement.elementIterator(); while (nodes.hasNext()) { Element node = nodes.next(); String id = node.attributeValue("id"); String parameterType = node.attributeValue("parameterType"); String resultType = node.attributeValue("resultType"); String sql = node.getText(); MapperNode selectnode = new MapperNode(); selectnode.setNamespace(namespace); selectnode.setId(id); selectnode.setParameterType(parameterType); selectnode.setResultType(resultType); selectnode.setSql(sql); selectnode.setParameter(""); this.mapperNodeMap.put(namespace + "." + id, selectnode); } } catch (Exception ex) { ex.printStackTrace(); } return this.mapperNodeMap; } This implementation: Uses DOM4J for XML parsing Extracts SQL statements and metadata Creates MapperNode objects MapperNode Structure The MapperNode class represents a single SQL statement: public class MapperNode { String namespace; String id; String parameterType; String resultType; String sql; String parameter; // Getters and setters } Features: Namespace and ID for unique identification Parameter and result type information SQL statement storage Parameter mapping support SqlSession Implementation The DefaultSqlSession handles SQL execution: public class DefaultSqlSession implements SqlSession { JdbcTemplate jdbcTemplate; SqlSessionFactory sqlSessionFactory; @Override public Object selectOne(String sqlid, Object[] args, PreparedStatementCallBack pstmtcallback) { String sql = this.sqlSessionFactory.getMapperNode(sqlid).getSql(); return jdbcTemplate.query(sql, args, pstmtcallback); } } Key aspects: SQL statement retrieval Parameter binding Result mapping JDBC template integration Integration with Spring Ioc: The Mybatis integration leverages Spring's IoC container: @Autowired JdbcTemplate jdbcTemplate; Benefits: Automatic dependency injection Transaction management Connection pooling Resource management XML Configuration Example mapper XML configuration: SELECT * FROM users WHERE id = ? Usage Example Here's how to use the Mybatis integration: @Repository public class UserDao { @Autowired private SqlSessionFactory sqlSessionFactory; public User findById(Integer id) { SqlSession session = sqlSessionFactory.openSession(); try { return (User) session.selectOne( "com.example.UserMapper.findById", new Object[]{id}, new UserRowMapper() ); } finally { session.close(); } } } Key Features Mapper XML Support XML-Based SQL configuration Dynamic SQL support Parameter mapping Session Management Connection handing Transaction boundaries Resource cleanup Result Mapping Object mapping Type conversion Collection handing Spring Integration IoC container support Transaction management Resource manageme

Mar 27, 2025 - 04:46

Spring Architecture Series-5.Implementing Mybatis Integration

Introduction

MyBatis is a popular persistence framework that provides a flexible way to map SQL statements to Java objects.In this article, I'll explore how to implements MyBatis integration in aSpring-like framework,base on my miniSpring project's implementation.

Core Components

The MyBatis integration consists of several key components:

src/com/yaruyng/batis/
├── DefaultSqlSessionFactory.java
├── DefaultSqlSession.java
├── SqlSessionFactory.java
├── SqlSession.java
└── MapperNode.java

SqlSessionFactory Implementation

The SqlSessionFactory is the entry point for creating SqlSession instance:

public class DefaultSqlSessionFactory implements SqlSessionFactory {
    @Autowired
    JdbcTemplate jdbcTemplate;

    String mapperLocations;
    Map<String, MapperNode> mapperNodeMap = new HashMap<>();

    public void init() {
        scanLocation(this.mapperLocations);
        // Initialize mapper nodes
    }

    @Override
    public SqlSession openSession() {
        SqlSession newSqlSession = new DefaultSqlSession();
        newSqlSession.setJdbcTemplate(jdbcTemplate);
        newSqlSession.setSqlSessionFactory(this);
        return newSqlSession;
    }
}

key features:

Integration with Spring's IoC container
Mapper XML file scanning
Session management

Mapper XML Parsing

The framework parse MyBatis mapper XML files:

private Map<String, MapperNode> buildMapperNodes(String filePath) {
    SAXReader saxReader = new SAXReader();
    URL xmlPath = this.getClass().getClassLoader().getResource(filePath);
    try {
        Document document = saxReader.read(xmlPath);
        Element rootElement = document.getRootElement();
        String namespace = rootElement.attributeValue("namespace");

        Iterator<Element> nodes = rootElement.elementIterator();
        while (nodes.hasNext()) {
            Element node = nodes.next();
            String id = node.attributeValue("id");
            String parameterType = node.attributeValue("parameterType");
            String resultType = node.attributeValue("resultType");
            String sql = node.getText();

            MapperNode selectnode = new MapperNode();
            selectnode.setNamespace(namespace);
            selectnode.setId(id);
            selectnode.setParameterType(parameterType);
            selectnode.setResultType(resultType);
            selectnode.setSql(sql);
            selectnode.setParameter("");

            this.mapperNodeMap.put(namespace + "." + id, selectnode);
        }
    } catch (Exception ex) {
        ex.printStackTrace();
    }
    return this.mapperNodeMap;
}

This implementation:

Uses DOM4J for XML parsing
Extracts SQL statements and metadata
Creates MapperNode objects

MapperNode Structure

The MapperNode class represents a single SQL statement:

public class MapperNode {
    String namespace;
    String id;
    String parameterType;
    String resultType;
    String sql;
    String parameter;

    // Getters and setters
}

Features:

Namespace and ID for unique identification
Parameter and result type information
SQL statement storage
Parameter mapping support

SqlSession Implementation

The DefaultSqlSession handles SQL execution:

public class DefaultSqlSession implements SqlSession {
    JdbcTemplate jdbcTemplate;
    SqlSessionFactory sqlSessionFactory;

    @Override
    public Object selectOne(String sqlid, Object[] args, 
            PreparedStatementCallBack pstmtcallback) {
        String sql = this.sqlSessionFactory.getMapperNode(sqlid).getSql();
        return jdbcTemplate.query(sql, args, pstmtcallback);
    }
}

Key aspects:

SQL statement retrieval
Parameter binding
Result mapping
JDBC template integration

Integration with Spring Ioc:

The Mybatis integration leverages Spring's IoC container:

@Autowired
JdbcTemplate jdbcTemplate;

Benefits:

Automatic dependency injection
Transaction management
Connection pooling
Resource management

XML Configuration

Example mapper XML configuration:



 namespace="com.example.UserMapper">
     id="findById" parameterType="java.lang.Integer" 
            resultType="com.example.User">
        SELECT * FROM users WHERE id = ?

Usage Example

Here's how to use the Mybatis integration:

@Repository
public class UserDao {
    @Autowired
    private SqlSessionFactory sqlSessionFactory;

    public User findById(Integer id) {
        SqlSession session = sqlSessionFactory.openSession();
        try {
            return (User) session.selectOne(
                "com.example.UserMapper.findById",
                new Object[]{id},
                new UserRowMapper()
            );
        } finally {
            session.close();
        }
    }
}

Key Features

Mapper XML Support
- XML-Based SQL configuration
- Dynamic SQL support
- Parameter mapping
Session Management
- Connection handing
- Transaction boundaries
- Resource cleanup
Result Mapping
- Object mapping
- Type conversion
- Collection handing
Spring Integration
- IoC container support
- Transaction management
- Resource management

Implementation Details

Mapper Scanning

private void scanLocation(String location) {
    String sLocation = this.getClass().getClassLoader()
            .getResource("").getPath() + location;
    File dir = new File(sLocation);
    for (File file : dir.listFiles()) {
        if (file.isDirectory()) {
            scanLocation(location + "/" + file.getName());
        } else {
            buildMapperNodes(location + "/" + file.getName());
        }
    }
}

SQL Execution

public Object selectOne(String sqlid, Object[] args, 
        PreparedStatementCallBack pstmtcallback) {
    String sql = this.sqlSessionFactory.getMapperNode(sqlid).getSql();
    return jdbcTemplate.query(sql, args, pstmtcallback);
}

Best Practice

Resource Management
- Proper session cleanup
- Connection pooling
- Transaction boundaries
Error Handling
- SQL exception handling
- Resource cleanup in finally blocks
- Proper error propagation
Performance Optimization
- Statement caching
- Connection pooling
- Batch processing support

Common Challenges and Solutions

Connection Management
- Use connection pooling
- Implement proper cleanup
- Handle transaction boundaries
SQL Mapping
- Proper parameter binding
- Result type conversion
- Collection handling
Transaction Management
- Spring transaction integration
- Proper isolation levels
- Rollback handling

Conclusion

Implementing MyBatis integration in a Spring-like framework provides:

Clean separation of concerns
Flexible SQL mapping
Transaction management
Resource optimization Key takeaways:
Understanding MyBatis core concepts
Spring integration patterns
Resource management
Performance considerations

This implementation demonstrates how to create a robust ORM framework integration while maintaining simplicity and flexibility.