SpringBoot动态切换多数据源

    @Bean(name = "dataSource")
    public DataSource dataSource() {
        DruidDataSource druidDataSource = new DruidDataSource();
        druidDataSource.setUrl(url);
        druidDataSource.setUsername(username);
        druidDataSource.setDriverClassName(driverClassName);
        druidDataSource.setPassword(password);
        return druidDataSource;
    }

@EnableConfigurationProperties({DruidStatProperties.class, DataSourceProperties.class})

  @Bean(initMethod = "init")
    @ConditionalOnMissingBean
    public DataSource dataSource() {
        LOGGER.info("Init DruidDataSource");
        return new DruidDataSourceWrapper();
    }

/* @Bean：向IOC容器中注入一个Bean
     * @ConfigurationProperties：使得配置文件中以spring.datasource为前缀的属性映射到Bean的属性中
     * @return
     */
    @ConfigurationProperties(prefix = "spring.datasource")
    @Bean
    public DataSource dataSource(){
        //做一些其他的自定义配置，比如密码加密等......
        return new DruidDataSource();
    }

@EnableConfigurationProperties(MybatisProperties.class)

mybatis.type-handlers-package=com.demo.typehandler
mybatis.configuration.map-underscore-to-camel-case=true

@Bean
  @ConditionalOnMissingBean
  public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {}

 /**
     * 注入SqlSessionFactory
     */
    @Bean("sqlSessionFactory1")
    public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource);
        sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:/mapper/**/*.xml"));
        org.apache.ibatis.session.Configuration configuration = new org.apache.ibatis.session.Configuration();
        // 自动将数据库中的下划线转换为驼峰格式
        configuration.setMapUnderscoreToCamelCase(true);
        configuration.setDefaultFetchSize(100);
        configuration.setDefaultStatementTimeout(30);
        sqlSessionFactoryBean.setConfiguration(configuration);
        return sqlSessionFactoryBean.getObject();
    }

@ConditionalOnSingleCandidate(DataSource.class)

private Map<Object, Object> targetDataSources;

protected abstract Object determineCurrentLookupKey();

/**
 * 使用ThreadLocal存储切换数据源后的KEY
 */
public class DataSourceHolder {

    //线程  本地环境
    private static final ThreadLocal<String> dataSources = new InheritableThreadLocal();

    //设置数据源
    public static void setDataSource(String datasource) {
        dataSources.set(datasource);
    }

    //获取数据源
    public static String getDataSource() {
        return dataSources.get();
    }

    //清除数据源
    public static void clearDataSource() {
        dataSources.remove();
    }
}

/**
 * 动态数据源，继承AbstractRoutingDataSource
 */
public class DynamicDataSource extends AbstractRoutingDataSource {

    /**
     * 返回需要使用的数据源的key，将会按照这个KEY从Map获取对应的数据源（切换）
     * @return
     */
    @Override
    protected Object determineCurrentLookupKey() {
        //从ThreadLocal中取出KEY
        return DataSourceHolder.getDataSource();
    }

    /**
     * 构造方法填充Map，构建多数据源
     */
    public DynamicDataSource(DataSource defaultTargetDataSource, Map<Object, Object> targetDataSources) {
        //默认的数据源，可以作为主数据源
        super.setDefaultTargetDataSource(defaultTargetDataSource);
        //目标数据源
        super.setTargetDataSources(targetDataSources);
        //执行afterPropertiesSet方法，完成属性的设置
        super.afterPropertiesSet();
    }
}

/**
 * 切换数据源的注解
 */
@Target(value = ElementType.METHOD)
@Retention(value = RetentionPolicy.RUNTIME)
@Documented
public @interface SwitchSource {

    /**
     * 默认切换的数据源KEY
     */
    String DEFAULT_NAME = "hisDataSource";

    /**
     * 需要切换到数据的KEY
     */
    String value() default DEFAULT_NAME;
}

@Aspect
//优先级要设置在事务切面执行之前
@Order(1)
@Component
@Slf4j
public class DataSourceAspect {

  // 切入点
    @Pointcut("@annotation(SwitchSource)")
    public void pointcut() {
    }

    /**
     * 在方法执行之前切换到指定的数据源
     * @param joinPoint
     */
    @Before(value = "pointcut()")
    public void beforeOpt(JoinPoint joinPoint) {
        /*因为是对注解进行切面，所以这边无需做过多判定，直接获取注解的值，进行环绕，将数据源设置成远方，然后结束后，清楚当前线程数据源*/
        Method method = ((MethodSignature) joinPoint.getSignature()).getMethod();
        SwitchSource switchSource = method.getAnnotation(SwitchSource.class);
        log.info("[Switch DataSource]:" + switchSource.value());
        DataSourceHolder.setDataSource(switchSource.value());
    }

    /**
     * 方法执行之后清除掉ThreadLocal中存储的KEY，这样动态数据源会使用默认的数据源
     */
    @After(value = "pointcut()")
    public void afterOpt() {
        DataSourceHolder.clearDataSource();
        log.info("[Switch Default DataSource]");
    }
}

/**
     * 创建动态数据源的SqlSessionFactory，传入的是动态数据源
     * @Primary这个注解很重要，如果项目中存在多个SqlSessionFactory，这个注解一定要加上
     */
    @Primary
    @Bean("sqlSessionFactory2")
    public SqlSessionFactory sqlSessionFactoryBean(DynamicDataSource dynamicDataSource) throws Exception {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dynamicDataSource);
        sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:/mapper/**/*.xml"));
        org.apache.ibatis.session.Configuration configuration = new org.apache.ibatis.session.Configuration();
        configuration.setMapUnderscoreToCamelCase(true);
        configuration.setDefaultFetchSize(100);
        configuration.setDefaultStatementTimeout(30);
        sqlSessionFactoryBean.setConfiguration(configuration);
        return sqlSessionFactoryBean.getObject();
    }

 /**
     * @Bean：向IOC容器中注入一个Bean
     * @ConfigurationProperties：使得配置文件中以spring.datasource为前缀的属性映射到Bean的属性中
     */
    @ConfigurationProperties(prefix = "spring.datasource")
    @Bean("dataSource")
    public DataSource dataSource(){
        return new DruidDataSource();
    }

    /**
     * 向IOC容器中注入另外一个数据源
     * 全局配置文件中前缀是spring.datasource.his
     */
    @Bean(name = SwitchSource.DEFAULT_NAME)
    @ConfigurationProperties(prefix = "spring.datasource.his")
    public DataSource hisDataSource() {
        return DataSourceBuilder.create().build();
    }

   /**
     * 重写事务管理器，管理动态数据源
     */
    @Primary
    @Bean(value = "transactionManager2")
    public PlatformTransactionManager annotationDrivenTransactionManager(DynamicDataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

   //不开启事务
    @Transactional(propagation = Propagation.NOT_SUPPORTED)
    //切换到HIS的数据源
    @SwitchSource
    @Override
    public List<DeptInfo> list() {
        return hisDeptInfoMapper.listDept();
    }

@Configuration
@MapperScan(basePackages = {"${mybatis.type-dao-package:com.bgy.auth.dao.adapter}"}, sqlSessionFactoryRef = "sqlSessionFactory")
@EnableTransactionManagement
@AutoConfigureOrder(-100)
@AutoConfigureAfter({MybatisPlusAutoConfiguration.class})
public class DatasourceConfig extends AbsDataSourceConfig {
  ...
    
    /**
     * +定义主数据源
     *
     * @return 主数据源（动态库）
     */
    @ConditionalOnExpression("${datasource.multi-tenant.enable:false}==true")
    @Bean(name = "dataSource"/*, destroyMethod = "close"*/)
    @Primary
    public DynamicDataSource dynamicDataSource(@Qualifier("dataSourcePropertiesMaster") DataSourceProperties properties,
                                               @Qualifier("dataSourceConfigInfoCollect") DataSourceConfigInfoCollect dataSourceConfigInfoCollect) throws Exception {
        CommonDataSource commonDataSource = createDataSource(properties);
        DataSource dataSource = (DataSource) commonDataSource;
        if (dataSource == null) {
            throw new Exception("Init DataSource Error!");
        }

        DynamicDataSource dynamicDataSource = new DynamicDataSource();
    // 默认数据库
        dynamicDataSource.setDefaultTargetDataSource(dataSource);
    // 切换的目标数据库
        dynamicDataSource.setTargetDataSources(getDataSourceMap(properties, dataSourceConfigInfoCollect));

        return dynamicDataSource;
    }
  ...
}

public class DynamicDataSource extends AbstractRoutingDataSource {
    @Override
    protected Object determineCurrentLookupKey() {
        // 获取当前动态数据源
        return DynamicDataSourceHolder.get();
    }
}

public class DynamicDataSourceHolder {
    public static final ThreadLocal<String> DATA_SOURCE_NAME = new ThreadLocal<>();

    public static void set(String name){
        DATA_SOURCE_NAME.set(name);
    }

    public static void clear(){
        DATA_SOURCE_NAME.remove();
    }

    public static String  get(){
        return DATA_SOURCE_NAME.get();
    }
}

@Configuration
public class DynamicDataSourceInterceptor implements HandlerInterceptor {
    protected static Log logger = LogFactory.getLog("DAO.LOG");
    @Autowired
    private DataSourceConfigInfoCollect dataSourceConfigInfoCollect;
    @Value("${datasource.multi-tenant.enable:false}")
    private Boolean dataSourceEnableMultiTenant;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        if (!dataSourceEnableMultiTenant) {
            return true;
        }

        final String appCode = request.getParameter("appCode");
        if (StringUtils.isBlank(appCode)) {
            logger.error("appCode can not be null!");
            throw new UnsupportedOperationException("appCode can not be null!");
        }

        String dataSourceKey = null;
        for (DataSourceConfigInfo configInfo : dataSourceConfigInfoCollect.getDbConfigList()) {
            if (configInfo.getAppCodeList().contains(appCode)) {
                dataSourceKey = configInfo.getKey();
                break;
            }
        }

        // 没该行代码就访问到了datasource.master的default数据源（datasource[master]）
        if (StringUtils.isBlank(dataSourceKey)) {
            logger.error("There is no database mapped to the appCode(" + appCode + ")!");
            throw new UnsupportedOperationException("There is no database mapped to the appCode(" + appCode + ")!");
        }

        DynamicDataSourceHolder.set(dataSourceKey);
        return true;
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        DynamicDataSourceHolder.clear();
    }
}