SpringBoot+MyBatis操作多数据源

本文将对如何使用Springboot+MyBatis操作多数据源进行简单示例和介绍，项目的完整目录层次如下图所示。

添加依赖与配置

首先，需要在工程POM文件中引入MyBatis和MySQL的Maven依赖。

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.4.1.RELEASE</version>
	</parent>
	<dependencies>
		<!-- 添加 MyBatis -->
		<dependency>
			<groupId>org.mybatis.spring.boot</groupId>
			<artifactId>mybatis-spring-boot-starter</artifactId>
			<version>1.2.0</version>
		</dependency>
		<!-- 添加 MySQL -->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
		</dependency>
	</dependencies>

其中mybatis-spring-boot-starter是 MyBatis 官方提供的Starter， 其Github 源码地址: https://github.com/mybatis/spring-boot-starter 。
此外，mybatis-spring-boot-stater 的官方文档地址：http://www.mybatis.org/spring-boot-starter/，MyBatis 官方中文文档地址：http://www.mybatis.org/mybatis-3/zh/java-api.html 。
然后，在核心配置文件application.properties中添加数据源相关配置。

#########################################################
### Primary DataSource -- DataSource 1 configuration  ###
#########################################################
primary.datasource.url=jdbc:mysql://localhost:3306/dev1?useUnicode=true&characterEncoding=utf8
primary.datasource.driverClassName=com.mysql.jdbc.Driver
primary.datasource.username=root
primary.datasource.password=123456

#########################################################
### Secondary DataSource -- DataSource 2 configuration ##
#########################################################
secondary.datasource.url=jdbc:mysql://localhost:3306/dev2?useUnicode=true&characterEncoding=utf8
secondary.datasource.driverClassName=com.mysql.jdbc.Driver
secondary.datasource.username=root
secondary.datasource.password=123456

配置数据源

首先，分别为每一个数据源各定义一个配置类，在配置类中通过注解@MapperScan来为不同包下的Mapper分别创建不同SqlSessionFactory、SqlSessionTemplate和DataSourceTransactionManager，用来操作不同的数据源。

/**
 * 数据源 1 配置类
 */
@Configuration
@MapperScan(basePackages = "com.pengjunlee.primary.mapper", sqlSessionTemplateRef = "primarySqlSessionTemplate")
public class PrimaryDataSourceConfig {

	@Bean(name = "primaryDataSource")
	@ConfigurationProperties(prefix = "primary.datasource")
	public DataSource primaryDataSource() {
		return DataSourceBuilder.create().build();
	}

	@Bean
	@ConfigurationProperties(prefix = "primary.datasource")
	@Primary
	public DataSource createDataSource() {
		return DataSourceBuilder.create().build();
	}

	@Primary
	@Bean(name = "primarySqlSessionFactory")
	public SqlSessionFactory primarySqlSessionFactory(@Qualifier("primaryDataSource") DataSource dataSource)
			throws Exception {
		SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
		bean.setDataSource(dataSource);
		bean.setMapperLocations(
				new PathMatchingResourcePatternResolver().getResources("classpath:mybatis/mapper/primary/*.xml"));
		return bean.getObject();
	}

	@Primary
	@Bean(name = "primaryTransactionManager")
	public DataSourceTransactionManager primaryTransactionManager(
			@Qualifier("primaryDataSource") DataSource dataSource) {
		return new DataSourceTransactionManager(dataSource);
	}

	@Primary
	@Bean(name = "primarySqlSessionTemplate")
	public SqlSessionTemplate primarySqlSessionTemplate(
			@Qualifier("primarySqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
		return new SqlSessionTemplate(sqlSessionFactory);
	}

}

/**
 * 数据源 2 配置类
 */
@Configuration
@MapperScan(basePackages = "com.pengjunlee.secondary.mapper", sqlSessionTemplateRef = "secondarySqlSessionTemplate")
public class SecondaryDataSourceConfig {

	@Bean(name = "secondaryDataSource")
	@ConfigurationProperties(prefix = "secondary.datasource")
	public DataSource secondaryDataSource() {
		return DataSourceBuilder.create().build();
	}

	@Bean(name = "secondarySqlSessionFactory")
	public SqlSessionFactory secondarySqlSessionFactory(@Qualifier("secondaryDataSource") DataSource dataSource)
			throws Exception {
		SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
		bean.setDataSource(dataSource);
		bean.setMapperLocations(
				new PathMatchingResourcePatternResolver().getResources("classpath:mybatis/mapper/secondary/*.xml"));
		return bean.getObject();
	}

	@Bean(name = "secondaryTransactionManager")
	public DataSourceTransactionManager secondaryTransactionManager(
			@Qualifier("secondaryDataSource") DataSource dataSource) {
		return new DataSourceTransactionManager(dataSource);
	}

	@Bean(name = "secondarySqlSessionTemplate")
	public SqlSessionTemplate secondarySqlSessionTemplate(
			@Qualifier("secondarySqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
		return new SqlSessionTemplate(sqlSessionFactory);
	}

}

定义Mapper

由于注解@MapperScan是通过包名来区分哪些Mapper用来操作哪个数据源，故而需要将不同数据源的Mapper接口类定义在不同的包中。
此处为了示例，定义了User（用户）和Department（部门）两个实体类，分别对应数据源一和数据源二。

/**
 * 用户
 */
public class User {

	private Long id;

	private String name;

	private Integer age;

	// 此处省略get和set方法
}

/**
 * 部门
 */
public class Department {

	private Long id;

	private String name;

	// 此处省略get和set方法

}

package com.pengjunlee.primary.mapper;

import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;

import com.pengjunlee.bean.User;

/**
 * 数据源 1 Mapper
 */
@Mapper
public interface UserMapper {

	User selectById(@Param("id") Long id);

	void deleteById(@Param("id") Long id);
}

package com.pengjunlee.secondary.mapper;

import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import com.pengjunlee.bean.Department;

/**
 * 数据源 2 Mapper
 */
@Mapper
public interface DepartmentMapper {

	Department selectById(@Param("id") Long id);

	void deleteById(@Param("id") Long id);
}

注意：在定义Mapper接口的时候，其所在包一定要与配置文件中指定的包路径一致。

使用Mapper

在实际项目中我们一般都会将定义好的Mapper自动装配到Service层进行调用，此时要格外注意事务。
以使用UserMapper为例，UserService接口定义如下。

public interface UserService {

	// 根据主键查询用户
	User getUserById(Long id);

	// 根据主键删除用户
	void deleteUserById(Long id);
}

在接口实现类UserServiceImpl中自动装配UserMapper来完成对数据源1的操作。

@Service("userService")
public class UserServiceImpl implements UserService {

	@Autowired
	private UserMapper userMapper;

	@Override
	public User getUserById(Long id) {
		return userMapper.selectById(id);
	}

	@Override
	@Transactional("primaryTransactionManager")// 注意事务
	public void deleteUserById(Long id) {
		userMapper.deleteById(id);
		throw new RuntimeException();
	}

}

启动类测试

在启动类中进行测试，测试代码如下。

@SpringBootApplication
public class MyApplication {

	public static void main(String[] args) {
		ConfigurableApplicationContext context = SpringApplication.run(MyApplication.class, args);

		UserMapper userMapper = context.getBean(UserMapper.class);
		User user = userMapper.selectById(3L);
		System.out.println(user.getName());

		DepartmentMapper deptMapper = context.getBean(DepartmentMapper.class);
		Department dept = deptMapper.selectById(2L);
		System.out.println(dept.getName());

		// 通过删除操作测试事务
		// DepartmentService deptService =
		// context.getBean(DepartmentService.class);
		// deptService.deleteDepartmentById(2L);

		UserService userService = context.getBean(UserService.class);
		userService.deleteUserById(3L);
	}
}

启动程序，各数据源中的数据都能查询成功且支持事务。

本文项目源码已上传至CSDN，资源地址：