在使用 Spring Boot 和 MyBatis 动态切换数据源时遇到的问题以及解决方法
相关项目地址:https://github.com/helloworlde/SpringBoot-DynamicDataSource
1. org.apache.ibatis.binding.BindingException: Invalid bound statement (not found)
在使用了动态数据源后遇到了该问题，从错误信息来看是因为没有找到
*.xml文件而导致的，但是在配置文件中
确实添加了相关的配置，这种错误的原因是因为设置数据源后没有设置SqlSessionFactoryBean的typeAliasesPackage
和mapperLocations属性或属性无效导致的；
- 解决方法：
如果在应用的入口类中添加了
@SpringBootApplication(exclude = DataSourceAutoConfiguration.class),
在DataSourceConfigure类的中设置相关属性：
@Bean
@ConfigurationProperties(prefix = "mybatis")
public SqlSessionFactoryBean sqlSessionFactoryBean() {
SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(dynamicDataSource());
return sqlSessionFactoryBean;
}或者直接配置(不推荐该方式)：
@Bean
public SqlSessionFactoryBean sqlSessionFactoryBean() {
SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
sqlSessionFactoryBean.setTypeAliasesPackage("typeAliasesPackage");
sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("mapperLocations"));
sqlSessionFactoryBean.setDataSource(dynamicDataSource());
return sqlSessionFactoryBean;
}2. Consider marking one of the beans as @Primary, updating the consumer to accept multiple beans, or using @Qualifier to identify the bean that should be consumed
该异常在错误信息中已经说的很清楚了，是因为有多个
DataSource的实例，所以无法确定该引用那个实例
- 解决方法：
为数据源的某个
Bean添加@Primary注解，该Bean应当是通过DataSourceBuilder.create().build()
得到的Bean，而不是通过new AbstractRoutingDataSource的子类实现的Bean，在本项目中可以是master()
或slave()得到的DataSource，不能是dynamicDataSource()得到的DataSource
3. 通过注解方式动态切换数据源无效
- 请确认注解没有放到 DAO 层方法上, 因为会在 Service 层开启事务，所以当注解在 DAO 层时不会生效
- 请确认以下
Bean正确配置：
@Bean("dynamicDataSource")
public DataSource dynamicDataSource() {
DynamicRoutingDataSource dynamicRoutingDataSource = new DynamicRoutingDataSource();
Map<Object, Object> dataSourceMap = new HashMap<>(2);
dataSourceMap.put("master", master());
dataSourceMap.put("slave", slave());
// Set master datasource as default
dynamicRoutingDataSource.setDefaultTargetDataSource(master());
// Set master and slave datasource as target datasource
dynamicRoutingDataSource.setTargetDataSources(dataSourceMap);
// To put datasource keys into DataSourceContextHolder to judge if the datasource is exist
DynamicDataSourceContextHolder.dataSourceKeys.addAll(dataSourceMap.keySet());
}
return dynamicRoutingDataSource;
}
@Bean
@ConfigurationProperties(prefix = "mybatis")
public SqlSessionFactoryBean sqlSessionFactoryBean() {
SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
// Here is very important, if don't config this, will can't switch datasource
// put all datasource into SqlSessionFactoryBean, then will autoconfig SqlSessionFactory
sqlSessionFactoryBean.setDataSource(dynamicDataSource());
return sqlSessionFactoryBean;
}
4. @Transactional 注解无效，发生异常不回滚
- 请确认该
Bean得到正确配置，并且@Transactional的rollbackFor配置正确
@Bean
public PlatformTransactionManager transactionManager() {
return new DataSourceTransactionManager(dynamicDataSource());
}
5. 通过 AOP 判断 DAO 层方法名时切换数据源无效
当切面指向了 DAO 层后无论如何设置切面的顺序，都无法在执行查询之前切换数据源，但是切面改为 Service 层后可以正常工作
解决方法: 请确认
@Transactional注解是加在方法上而不是 Service 类上，添加了@Transactional的方法因为在 Service 层开启了事务，
会在事务结束之后才会切换数据源检出
DataSourceTransactionManagerBean 注入正确
@Bean
public PlatformTransactionManager transactionManager() {
return new DataSourceTransactionManager(dynamicDataSource());
}6. The dependencies of some of the beans in the application context form a cycle
- 错误信息：
The dependencies of some of the beans in the application context form a cycle:
produceController (field private cn.com.hellowood.dynamicdatasource.service.ProductService cn.com.hellowood.dynamicdatasource.controller.ProduceController.productService)
↓
productService (field private cn.com.hellowood.dynamicdatasource.mapper.ProductDao cn.com.hellowood.dynamicdatasource.service.ProductService.productDao)
↓
productDao defined in file [/Users/hehuimin/Downloads/Dev/SpringBoot/DynamicDataSource/out/production/classes/cn/com/hellowood/dynamicdatasource/mapper/ProductDao.class]
↓
sqlSessionFactoryBean defined in class path resource [cn/com/hellowood/dynamicdatasource/configuration/DataSourceConfigurer.class]
┌─────┐
| dynamicDataSource defined in class path resource [cn/com/hellowood/dynamicdatasource/configuration/DataSourceConfigurer.class]
↑
↓
| master defined in class path resource [cn/com/hellowood/dynamicdatasource/configuration/DataSourceConfigurer.class]
↑
↓
| dataSourceInitializer
└─────┘
这是因为在注入
DataSource的实例的时候产生了循环调用，第一个注入的 Bean 依赖于其他的 Bean， 而被依赖的 Bean 产生依赖传递，依赖第一个
注入的 Bean, 陷入了循环，无法启动项目
- 解决方法：将
@Primary注解指向没有依赖的 Bean，如：
/**
* master DataSource
* @Primary 注解用于标识默认使用的 DataSource Bean，因为有三个 DataSource Bean，该注解可用于 master
* 或 slave DataSource Bean, 但不能用于 dynamicDataSource Bean, 否则会产生循环调用
*
* @ConfigurationProperties 注解用于从 application.properties 文件中读取配置，为 Bean 设置属性
* @return data source
*/
@Bean("master")
@Primary
@ConfigurationProperties(prefix = "application.server.db.master")
public DataSource master() {
return DataSourceBuilder.create().build();
}
@Bean("slave")
@ConfigurationProperties(prefix = "application.server.db.slave")
public DataSource slave() {
return DataSourceBuilder.create().build();
}
@Bean("dynamicDataSource")
public DataSource dynamicDataSource() {
DynamicRoutingDataSource dynamicRoutingDataSource = new DynamicRoutingDataSource();
Map<Object, Object> dataSourceMap = new HashMap<>(2);
dataSourceMap.put("master", master());
dataSourceMap.put("slave", slave());
// Set master datasource as default
dynamicRoutingDataSource.setDefaultTargetDataSource(master());
// Set master and slave datasource as target datasource
dynamicRoutingDataSource.setTargetDataSources(dataSourceMap);
// To put datasource keys into DataSourceContextHolder to judge if the datasource is exist
DynamicDataSourceContextHolder.dataSourceKeys.addAll(dataSourceMap.keySet());
return dynamicRoutingDataSource;
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