SpringBoot動態數據源與@Transactional

場景：saas服務，不同的項目，使用同一個服務，不同的租戶對應不同的庫

數據庫操作框架使用 nutz，連接池使用Druid

問題：需要根據請求不同租戶的請求，相應不同的數據庫，並且支持事務@Transactional

思路：1.使用ThreadLocal，維持多數據源的上下文

        2.使用切面的方式切換上下文

        3. 自定義AbstractRoutingDataSource的子類，持有數據庫上下文的變量，根據當前數據庫上下文返回需要的數據庫

代碼：

1.自定義AbstractRoutingDataSource的子類，並持有數據庫上下文的變量

 public class MultiDataSource extends AbstractRoutingDataSource {
    //持有的數據庫上下文，將在切面中設置當前請求的數據庫上下文
     private static ThreadLocal<String> datasourceHolder = new ThreadLocal();
    
    @Override
    protected Object determineCurrentLookupKey() {
        return datasourceHolder.get();
    }

    public static void setDataSource(String dataSource){
        datasourceHolder.set(dataSource);
    }

    public static String getDataSource(){
        return datasourceHolder.get();
    }

    public static void remove(){
         datasourceHolder.remove();
    }

}

2.自定義切面，切點是所有的service包及子包，根據companyId,來構建不同的DataSource的key

@Slf4j
@Component
@Aspect
@Order(-1) //這個注解很重要，是個坑，跟了很久才決定加上 public class DataSourceSwitchAspect {
    @Pointcut("execution(* com.logan.service..*.*(..))")
    public void dataSourceSwitchPointCut(){

    }

    @Around("dataSourceSwitchPointCut()")
    public Object before(ProceedingJoinPoint point) throws Throwable {
            //設置DataSource
        String companyId = HttpRequestUtils.getCurrentCompanyId();
        if(StringUtils.isEmpty(companyId)){
            MethodSignature ms = (MethodSignature) point.getSignature();
            Method method = ms.getMethod();
            //這里主要是處理在@Async的時候，MultiDataSource的數據源設置，只能通過參數獲取
            for (int i = 0; i < method.getParameters().length; i++) {
                if (method.getParameters()[i].getName().equals(TO_COMPANY_ID)) {
                    Object toCompanyId = point.getArgs()[i];
                    if (toCompanyId != null) {
                        companyId = toCompanyId.toString();
                    }
                    break;
                }
            }
        }
        if(StringUtils.isNotEmpty(companyId)){
            String dsName = String.format("ds%s",companyId);
            MultiDataSource.setDataSource(dsName);
        }
        try{
           return point.proceed();
        }finally {
            //最后一定要釋放，否則MultiDataSource里面的對象會一直增長
              MultiDataSource.remove(); 

 } 
 }
 }

 3.定義注入多數據源配置信息

@Configuration
public class DruidConfiguration {
    @Bean
    public ServletRegistrationBean druidStatViewServle2(){

        //org.springframework.boot.context.embedded.ServletRegistrationBean提供類的進行注冊.
        ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean(new StatViewServlet(),"/druid/*");
        //添加初始化參數：initParams
        servletRegistrationBean.addInitParameter("loginUsername","account");
        servletRegistrationBean.addInitParameter("loginPassword","123456");
        //是否能夠重置數據.
        servletRegistrationBean.addInitParameter("resetEnable","false");
        return servletRegistrationBean;
    }

    /**
     * 注冊一個：filterRegistrationBean
     * @return
     */
    @Bean
    public FilterRegistrationBean druidStatFilter2(){

        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean(new WebStatFilter());
        //添加過濾規則.
        filterRegistrationBean.addUrlPatterns("/*");
        //添加不需要忽略的格式信息.
        filterRegistrationBean.addInitParameter("exclusions","*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid2/*");
        return filterRegistrationBean;
    }

    @Bean
    @ConfigurationProperties(prefix = "spring.datasources.ds1")
    public DataSource ds1(){
        DataSource dataSource = DataSourceBuilder.create().type(DruidDataSource.class).build();
        return dataSource;
    }

    @Bean
    @ConfigurationProperties(prefix = "spring.datasources.ds2")
    public DataSource ds2(){
        DataSource dataSource = DataSourceBuilder.create().type(DruidDataSource.class).build();
        return dataSource;
    }

    @Bean
    @ConfigurationProperties(prefix = "spring.datasources.ds3")
    public DataSource ds3(){
        DataSource dataSource = DataSourceBuilder.create().type(DruidDataSource.class).build();
        return dataSource;
    }

    @Bean
    @ConfigurationProperties(prefix = "spring.datasources.ds4")
    public DataSource ds4(){
        DataSource dataSource = DataSourceBuilder.create().type(DruidDataSource.class).build();
        return dataSource;
    }

    @Bean
    public DataSource dataSource(){
        MultiDataSource dynamicRoutingDataSource = new MultiDataSource();
        //配置多數據源
        Map<Object, Object> dataSourceMap = new HashMap<>(2);
        dataSourceMap.put("ds1", ds1());
        dataSourceMap.put("ds2", ds2());
        dataSourceMap.put("ds3", ds3());
        dataSourceMap.put("ds4", ds4());
        // 將 ds1 數據源作為默認指定的數據源
       dynamicRoutingDataSource.setDefaultTargetDataSource(ds1());
       dynamicRoutingDataSource.setTargetDataSources(dataSourceMap);
        return dynamicRoutingDataSource;
    }

    @Bean
    public PlatformTransactionManager txManager(DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

}

4.使用的是nutz，要想將事務交個Spring托管，必須還要設置DaoRunner

/**
 * 為了使得NutDao兼容Spring事務而設置的DaoRunner
 *
 */
@Repository
public class SpringDaoRunnerForNutz implements DaoRunner {

    @Override
    public void run(DataSource dataSource, ConnCallback callback) {
        Connection con = DataSourceUtils.getConnection(dataSource);
        try {
            callback.invoke(con);
        }
        catch (Exception e) {
            if (e instanceof RuntimeException) {
                throw (RuntimeException) e;
            } else {
                throw new RuntimeException(e);
            }
        } finally {
            DataSourceUtils.releaseConnection(con, dataSource);
        }
    }

}

 

 

使用樣例：

@Service
public class TransactionTest {

    @Autowired
    private UserDODao userDODao;

    @Transactional(rollbackFor = Exception.class,isolation = Isolation.READ_COMMITTED,propagation = Propagation.REQUIRED)
    public void testTransaction(Integer i,String toCompanyId){
        System.out.println(String.format("Async DateContext：%s",MultiDataSource.getDataSource()));
        UserDO userDO = userDODao.fetchByUserName("aaa");
        String name = userDO.getName();
        userDO.setName(name+"1次修改");
        System.out.println(String.format("修改1次:%s",userDO.getName()));
        userDODao.update(userDO);
        if(!i.equals(0)) {
            int j = 1 / 0;
        }
        userDO.setName(name +"2次修改");
        System.out.println(String.format("修改2次:%s",userDO.getName()));
        userDODao.update(userDO);
        userDO = userDODao.fetchByUserName("aaa");
        if(userDO != null){
            System.out.println(userDO.getName());
        }

    }

}

 

 

 

踩坑：

雖然我們通過切面去做數據源的上下文切換，但是發現並不起作用，在跟蹤TransactionalManager的過程中發現自己定義的切面執行時機晚於@Transactional(我們知道Spring是通過切面去做事務管理的)，所以我們需要人為的將切換數據源的切面提前，就有了咱們自定義切面里面增加的注解@Order(-1)