最近在做一个数据库下线的需求,配置了多个数据源,要把数仓对应的默认数据源下线,涉及了很多和spring容器相关的注解.

Spring 容器相关注解

@Configuration：表明一个类是配置类,@Configuration标注的类等同于一个xml文件
@Bean: @Bean标注的方法等同于xml文件里的一个标签
@Primary
@Resource byName 类型的依赖注入。使用方式：@Resource(name="xxBean"). 不带参数的 @Resource 默认值类名首字母小写
@Autowired 其实就是 autowire=byType 就是根据类型的自动注入依赖,可以被使用在属性域，方法，构造函数上
@Qualifier:autowire=byName, @Autowired注解判断多个bean类型相同时，就需要使用 @Qualifier("xxBean") 来指定依赖的bean的id
@Configuration

代码改造过程

代码改造完成后，准备把adb对应的数据源注释掉，看程序哪里会报错，也许可以看到哪里没有改到。
原来的写法：（主数据源）

@Configuration
public class OdsMybatisConfig {
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource")
    @Primary
    public DataSource dataSource(){
        return DataSourceBuilder.create().type(DruidDataSource.class).build();
    }

    @Bean
    @Primary
    public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:META-INF/mybatis/mapper/**/*Mapper.xml"));
        return bean.getObject();
    }

    @Bean
    @Primary
    public DataSourceTransactionManager transactionManager(DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

    @Bean
    @Primary
    public SqlSessionTemplate sqlSessionTemplate(SqlSessionFactory sqlSessionFactory) throws Exception {
        sqlSessionFactory.getConfiguration().setMapUnderscoreToCamelCase(true);
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}

使用主数据源：

@Repository
public class ImporterInformationDaoImpl extends BaseDaoImpl<ImporterInformation> implements ImporterInformationDao {
    @Resource
    ImporterInformationMapper importerInformationMapper;

    @Override
    protected BaseMapper<ImporterInformation> getBaseMapper() {
        return importerInformationMapper;
    }
}

使用非主数据源：

@Repository("FbaConsignmentExport")
public class FbaConsignmentExportData<R, T> implements ExportDataQueryDao<R, T> {

    @Resource
    @Qualifier("masterSqlSessionFactory")
    private SqlSessionTemplate masterSqlSessionTemplate;

    @Override
    public Integer count(R condition) {
        FbaConsignmentExportMapper mapper = masterSqlSessionTemplate.getMapper(FbaConsignmentExportMapper.class);
        return mapper.countExportFbaConsignment((FbaConsignmentExportCriteria) condition);
    }

    @Override
    public List<T> queryData(R condition) {
        FbaConsignmentExportMapper mapper = masterSqlSessionTemplate.getMapper(FbaConsignmentExportMapper.class);
        return (List<T>) mapper.exportFbaConsignment((FbaConsignmentExportCriteria) condition);
    }
}

注释掉主数据源的@Configuration之后，重启报skuMapper找不到SqlSessionFactory，各种尝试还是无解，包括升级mysql版本...
大佬给我发来这样两行代码，竟然可以...

@MapperScan(basePackages = "com.fpx.fb4.datawh.provider.mdata.sku.dao", sqlSessionFactoryRef = "mdataSlaveSqlSessionFactory")
public class mdataSlaveMybatisConfig {

疑问（未解决）

1. 为什么这个tempate注入不进来

   
   
   

   怀疑是加载顺序的问题，配置类没装配完，就开始装配这里，只是怀疑...或者是template和mapper之间有问题

    @Resource
    @Qualifier("masterSqlSessionTemplate")
    private SqlSessionTemplate masterSqlSessionTemplate;

    private InventoryDiffMapper inventoryDiffMapper;

    @PostConstruct
    public void init(){
        inventoryDiffMapper = masterSqlSessionTemplate.getMapper(InventoryDiffMapper.class);
    }

同事写了这样的代码，已经上线且运行良好，spring的生命周期要着重了解一下了~

2. 这里masterSqlSessionTemplate注入masterSqlSessionFactory怎么能注入进来呢

@Repository("FbaConsignmentExport")
public class FbaConsignmentExportData<R, T> implements ExportDataQueryDao<R, T> {

    @Resource
    @Qualifier("masterSqlSessionFactory")
    private SqlSessionTemplate masterSqlSessionTemplate;

    @Override
    public Integer count(R condition) {
        FbaConsignmentExportMapper mapper = masterSqlSessionTemplate.getMapper(FbaConsignmentExportMapper.class);
        return mapper.countExportFbaConsignment((FbaConsignmentExportCriteria) condition);
    }

    @Override
    public List<T> queryData(R condition) {
        FbaConsignmentExportMapper mapper = masterSqlSessionTemplate.getMapper(FbaConsignmentExportMapper.class);
        return (List<T>) mapper.exportFbaConsignment((FbaConsignmentExportCriteria) condition);
    }
}

号外

springboot的多数据源：https://www.imooc.com/article/details/id/44010

你能抓住变化中不变的东西吗