说明

通过在翟永超的博客学习了多数据源的配置章节后，发现当结合实际的需求使用时还有些困难，于是找资料学习了结合mybatis的多数据源配置，在这里记录下。在学习中，使用了两个不同的mysql数据库，分别在本地和虚拟机，用来模拟不同ip的数据库，类似于分库分表后部署在不同地方的情况。

正文

本文通过使用不同的数据源，达到在不同库中查找不同的数据的目的。

1.项目的初始构建

添加依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.3.2</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>

通过手动配置数据源，要在项目启动类中排除数据源的自动配置

@SpringBootApplication
@EnableAutoConfiguration(exclude = {DataSourceAutoConfiguration.class})
public class MulDatasourceApplication extends SpringBootServletInitializer {

    public static void main(String[] args) {
        SpringApplication.run(MulDatasourceApplication.class, args);
    }
}

2.在application.properties中添加配置

#第一数据源
datasource.first.driverClassName=com.mysql.jdbc.Driver
datasource.first.url=jdbc:mysql://ip:3306/dataBase?characterEncoding=UTF-8
datasource.first.username=**
datasource.first.password=**

#第二数据源
datasource.second.driverClassName=com.mysql.jdbc.Driver
datasource.second.url=jdbc:mysql://ip:3306/dataBase?characterEncoding=UTF-8
datasource.second.username=**
datasource.second.password=**

3.编写注解类

该注解用于mybatis的查询时标注接口使用的数据源
第一数据源 UseDatasourceFirst

@Retention(RetentionPolicy.CLASS)
@Target(ElementType.TYPE)
public @interface UseDatasourceFirst {
}

第二数据源 UseDatasourceSecond

@Retention(RetentionPolicy.CLASS)
@Target(ElementType.TYPE)
public @interface UseDatasourceSecond {
}

4.配置数据源

第一数据源配置

@Configuration
@MapperScan(basePackages = "com.example.mul_datasource.db.dao", annotationClass = UseDatasourceFirst.class, sqlSessionFactoryRef = FirstDatasoruceConfig.SQL_SESSION_FACTOR_NAME)
public class FirstDatasoruceConfig {
    public static final String SQL_SESSION_FACTOR_NAME = "sqlSessionFactoryFirst";
    public static final String TRANSACTION_MANAGER="txManagerFirst";
    protected Logger logger = LoggerFactory.getLogger(FirstDatasoruceConfig.class);

    @Bean(name = "datasourceFirst")
    @Primary
    @ConfigurationProperties(prefix = "datasource.first")
    public DataSource dataSourceFirst(){
        return DataSourceBuilder.create().build();
    }

    @Bean(name = TRANSACTION_MANAGER)
    @Primary
    public PlatformTransactionManager txManagerFirst(@Qualifier("datasourceFirst") DataSource datasourceFirst){
        return new DataSourceTransactionManager(datasourceFirst);
    }

    @Bean(name = FirstDatasoruceConfig.SQL_SESSION_FACTOR_NAME)
    @Primary
    public SqlSessionFactory sqlSessionFactory(@Qualifier("datasourceFirst") DataSource datasourceFirst) throws Exception {
        SqlSessionFactoryBean sessionFactoryBean = new SqlSessionFactoryBean();
        sessionFactoryBean.setDataSource(datasourceFirst);
        sessionFactoryBean.setTypeAliasesPackage("com.example.mul_datasource.db.pojo");
        Resource[] resources = new PathMatchingResourcePatternResolver()
                               .getResources("classpath:com/example/mul_datasource/db/mapper/*Mapper.xml");
        sessionFactoryBean.setMapperLocations(resources);
        return sessionFactoryBean.getObject();
    }
}

第二数据源配置

@Configuration
@MapperScan(basePackages = "com.example.mul_datasource.db2.dao", annotationClass = UseDatasourceSecond.class, sqlSessionFactoryRef = SecondDatasourceConfig.SQL_SESSION_FACTORY_NAME)
public class SecondDatasourceConfig {
    public static final String SQL_SESSION_FACTORY_NAME = "sqlSessionFactorySecond";
    public static final String TRANSACTION_MANAGER = "txManageSecond";
    protected Logger logger = LoggerFactory.getLogger(SecondDatasourceConfig.class);

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

    @Bean(name = SecondDatasourceConfig.TRANSACTION_MANAGER)
    public PlatformTransactionManager txManagerSecond(@Qualifier("datasourceSecond") DataSource datasourceSecond){
        return new DataSourceTransactionManager(datasourceSecond);
    }

    @Bean(name = SQL_SESSION_FACTORY_NAME)
    public SqlSessionFactory sqlSessionFactory(@Qualifier(value = "datasourceSecond") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean sessionFactoryBean = new SqlSessionFactoryBean();
        sessionFactoryBean.setDataSource(dataSource);
        sessionFactoryBean.setTypeAliasesPackage("com.example.mul_datasource.db2.pojo");
        Resource[] resources = new PathMatchingResourcePatternResolver()
                               .getResources("classpath:com/example/mul_datasource/db2/mapper/*Mapper.xml");
        sessionFactoryBean.setMapperLocations(resources);
        return sessionFactoryBean.getObject();
    }
}

5.插件自动生成

通过上篇博文的学习《使用c3p0连接池集成mybatis及mybatis自动代码生成插件》，学习了如果使用插件自动生成代码。这里在第一个主机数据库中创建表teacher，在第二个虚机数据库中创建表student，利用插件分别生成pojo、mapper文件、mapper接口
分别放于不同的package中，在mapper接口类上配置使用编写的注解类

@UseDatasourceFirst
public interface TeacherMapper {
    int deleteByPrimaryKey(Integer id);

    int insert(Teacher record);

    int insertSelective(Teacher record);

    Teacher selectByPrimaryKey(Integer id);

    int updateByPrimaryKeySelective(Teacher record);

    int updateByPrimaryKey(Teacher record);
}

@UseDatasourceSecond
public interface StudentMapper {
    int deleteByPrimaryKey(Integer id);

    int insert(Student record);

    int insertSelective(Student record);

    Student selectByPrimaryKey(Integer id);

    int updateByPrimaryKeySelective(Student record);

    int updateByPrimaryKey(Student record);
}

6.测试

@Autowired
private TeacherMapper teacherMapper;

@Autowired
private StudentMapper studentMapper;

@Test
public void testSelectFirstDatasource(){
    Teacher teacher = teacherMapper.selectByPrimaryKey(1);
    System.out.println(teacher.getId() + "--" + teacher.getTname());
}

@Test
public void testSelectSecondDatasource(){
    Student student = studentMapper.selectByPrimaryKey(1);
    System.out.println(student.getId() + "--" + student.getUname() + "--" + student.getAge());
}

问题

在使用自动生成代码插件时，一直只生成insert语句，原因是未设置主键
数据库的权限问题
在配置数据库时，使用的参数名称必须符合要求，driverClassName,url,username,password

源码地址：https://github.com/Edenwds/springboot_study/tree/master/mul_datasource
参考资料：https://github.com/mybatis/spring-boot-starter/issues/78

springboot学习(四)：MyBatis多数据源配置

说明

正文