AbstractRoutingDataSource AOP如何实现动态数据源切换

## datasource master #
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/master?characterEncoding=UTF-8&serverTimezone=UTC
spring.datasource.username=root
spring.datasource.password=123456

## datasource slave #
spring.datasource-slave.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource-slave.driver-class-name=com.mysql.jdbc.Driver
spring.datasource-slave.url=jdbc:mysql://localhost:3306/slave?characterEncoding=UTF-8&serverTimezone=UTC
spring.datasource-slave.username=root
spring.datasource-slave.password=123456

public interface Datasources {
    String MASTER_DB = "masterDB";

    String SLAVE_DB = "slaveDB";
}

@Configuration
public class DataSourceConfig {
    //destroy-method="close"的作用是当数据库连接不使用的时候,就把该连接重新放到数据池中,方便下次使用调用.
    @Bean(destroyMethod = "close", name = Datasources.MASTER_DB)
    @ConfigurationProperties(prefix = "spring.datasource")
    public DataSource dataSource() {
        return DataSourceBuilder.create().type(DruidDataSource.class).build();
    }

    @Bean(destroyMethod = "close", name = Datasources.SLAVE_DB)
    @ConfigurationProperties(prefix = "spring.datasource-slave")
    public DataSource dataSourceSlave() {
        return DataSourceBuilder.create().type(DruidDataSource.class).build();
    }
}

@Configuration
@MapperScan(basePackages = {"com.example.dao"})
public class MybatisConfig {
    @Autowired
    @Qualifier(Datasources.MASTER_DB)
    private DataSource masterDB;

    @Autowired
    @Qualifier(Datasources.SLAVE_DB)
    private DataSource slaveDB;

    /**
     * 动态数据源
     */
    @Bean(name = "dynamicDataSource")
    public DataSource dynamicDataSource() {
        DynamicDataSource dynamicDataSource = new DynamicDataSource();
        // 默认数据源
        dynamicDataSource.setDefaultTargetDataSource(masterDB);

        // 配置多数据源
        Map<Object, Object> dsMap = new HashMap<>();
        dsMap.put(Datasources.MASTER_DB, masterDB);
        dsMap.put(Datasources.SLAVE_DB, slaveDB);
        dynamicDataSource.setTargetDataSources(dsMap);

        return dynamicDataSource;
    }

    @Bean
    @ConfigurationProperties(prefix = "mybatis")
    public SqlSessionFactoryBean sqlSessionFactoryBean() {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        // 配置数据源，此处配置为关键配置，如果没有将 dynamicDataSource 作为数据源则不能实现切换
        sqlSessionFactoryBean.setDataSource(dynamicDataSource());
        return sqlSessionFactoryBean;
    }
}

public class DataSourceContextHolder {
    /**
     * 默认数据源
     */
    public static final String DEFAULT_DATASOURCE = Datasources.MASTER_DB;

    private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();

    // 设置数据源名
    public static void setDB(String dbType) {
        System.out.println("切换到{}数据源:" +  dbType);
        contextHolder.set(dbType);
    }

    // 获取数据源名
    public static String getDB() {
        return (contextHolder.get());
    }

    // 清除数据源名
    public static void clearDB() {
        contextHolder.remove();
    }
}

@Aspect
@Component
public class DynamicDataSourceAspect {

    @Before("@annotation(com.example.util.RoutingDataSource)")
    public void beforeSwitchDS(JoinPoint joinPoint) {

        MethodSignature methodSignature = (MethodSignature) joinPoint.getSignature();
        Method method = methodSignature.getMethod();
        String dataSource = DataSourceContextHolder.DEFAULT_DATASOURCE;
        if (method.isAnnotationPresent(RoutingDataSource.class)) {
            RoutingDataSource routingDataSource = method.getDeclaredAnnotation(RoutingDataSource.class);
            dataSource = routingDataSource.value();
        }
        DataSourceContextHolder.setDB(dataSource);
    }

    @After("@annotation(com.example.util.RoutingDataSource)")
    public void afterSwitchDS(JoinPoint point) {
        DataSourceContextHolder.clearDB();
    }
}

public class DynamicDataSource extends AbstractRoutingDataSource{
    @Override
    protected Object determineCurrentLookupKey() {
        System.out.println("数据源为{}:" + DataSourceContextHolder.getDB());
        return DataSourceContextHolder.getDB();
    }
}

@SpringBootApplication(exclude = {
      DataSourceAutoConfiguration.class
})
public class CutDataBaseApplication {

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

/**
 * @author aYong
 * @version 1.0
 * @date 2019/7/24
 */
@RestController
@RequestMapping("/route")
public class SysUserController {
    @Autowired
    private SysUserService sysUserService;

    @GetMapping("/test1")
    public SysUser test1(long id) {
        return sysUserService.test1(id);
    }

    @GetMapping("/test2")
    public Integer test2(long id, String name) {
        return sysUserService.test2(id, name);
    }
}