SpringBoot集成AbstractRoutingDataSource实现动态切换多数据源

spring-jdbc模块提供了AbstractRoutingDataSource抽象类，其内部可以包含多个DataSource，只需要实现其抽象方法，在运行时就可以动态访问指定的数据库。

1. 引入核心依赖

新建一个springboot项目，pom.xml文件中引入如下依赖

<dependency>
    <groupId>org.springframework.bootgroupId>
    <artifactId>spring-boot-starter-jdbcartifactId>
dependency>
<dependency>
    <groupId>org.springframework.bootgroupId>
    <artifactId>spring-boot-starter-webartifactId>
dependency>
<dependency>
    <groupId>org.mybatis.spring.bootgroupId>
    <artifactId>mybatis-spring-boot-starterartifactId>
    <version>2.2.2version>
dependency>
<dependency>
    <groupId>mysqlgroupId>
    <artifactId>mysql-connector-javaartifactId>
    <scope>runtimescope>
dependency>
<dependency>
    <groupId>com.alibabagroupId>
    <artifactId>druid-spring-boot-starterartifactId>
    <version>1.2.9version>
dependency>
<dependency>
    <groupId>org.springframework.bootgroupId>
    <artifactId>spring-boot-starter-aopartifactId>
dependency>

2. application.yml文件

server:
  port: 8090
spring:
  application:
    name: springboot-dynamic-aop
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    master:
      jdbc-url: jdbc:mysql://localhost:3306/dynamic-master?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8
      username: root
      password: 123456
      driver-class-name: com.mysql.cj.jdbc.Driver
    slave:
      jdbc-url: jdbc:mysql://localhost:3306/dynamic-slave?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8
      username: root
      password: 123456
      driver-class-name: com.mysql.cj.jdbc.Driver
mybatis:
  mapper-locations: classpath:mapper/*.xml
  configuration:
    use-actual-param-name: true
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

3. 数据源配置类

@Configuration
public class DataSourceConfig {

    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.master")
    public DataSource masterDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.slave")
    public DataSource slaveDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean
    public DataSourceTransactionManager masterDataSourceTransactionManager(DynamicDataSource dynamicDataSource) {
        DataSourceTransactionManager dataSourceTransactionManager = new DataSourceTransactionManager();
        dataSourceTransactionManager.setDataSource(dynamicDataSource);
        return dataSourceTransactionManager;
    }

    @Bean
    public DataSourceTransactionManager slaveDataSourceTransactionManager(DynamicDataSource dynamicDataSource) {
        DataSourceTransactionManager dataSourceTransactionManager = new DataSourceTransactionManager();
        dataSourceTransactionManager.setDataSource(dynamicDataSource);
        return dataSourceTransactionManager;
    }
}

4. 动态数据源类

新建一个类继承AbstractRoutingDataSource，实现其抽象类

@Primary
@Component
public class DynamicDataSource extends AbstractRoutingDataSource {

    public static final ThreadLocal<String> name = new ThreadLocal<>();

    @Autowired
    DataSource masterDataSource;
    @Autowired
    DataSource slaveDataSource;

    @Override
    protected Object determineCurrentLookupKey() {
        return name.get();
    }

    @Override
    public void afterPropertiesSet() {
        Map<Object, Object> targetDataSources = new HashMap<>();
        targetDataSources.put("master", masterDataSource);
        targetDataSources.put("slave", slaveDataSource);
        //设置目标数据源
        super.setTargetDataSources(targetDataSources);
        //设置默认数据源
        super.setDefaultTargetDataSource(masterDataSource);
        super.afterPropertiesSet();
    }
}

5. 实现多数据源切换

一般情况下，读写分离的数据源使用MyBatis插件实现动态切换数据源，不同业务来源的数据源使用AOP结合自定义注解实现动态切换数据源

5.1. MyBatis插件实现动态切换

新建一个插件类，实现Interceptor接口

@Intercepts({
        @Signature(type = Executor.class, method = "update", args = {MappedStatement.class, Object.class}),
        @Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class})
})
public class DynamicDataSourcePlugin implements Interceptor {
    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        Object[] objects = invocation.getArgs();
        MappedStatement mappedStatement = (MappedStatement) objects[0];
        if (mappedStatement.getSqlCommandType().equals(SqlCommandType.SELECT)) {
            DynamicDataSource.name.set("slave");
        } else {
            DynamicDataSource.name.set("master");
        }
        return invocation.proceed();
    }

    @Override
    public Object plugin(Object target) {
        if (target instanceof Executor) {
            return Plugin.wrap(target, this);
        } else {
            return target;
        }
    }

    @Override
    public void setProperties(Properties properties) {

    }
}

再将DynamicDataSourcePlugin类加入DataSourceConfig配置类

@Bean
public Interceptor interceptor() {
    return new DynamicDataSourcePlugin();
}

5.2. AOP结合自定义注解实现

新建一个自定义注解DS

@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface DS {

    String value() default "";
}

新建切面类

@Aspect
@Component
public class DynamicDataSourceAspect implements Ordered {

    @Before("@within(ds)")
    public void before(JoinPoint joinPoint, DS ds) {
        DynamicDataSource.name.set(ds.value());
    }

    @Override
    public int getOrder() {
        return 0;
    }
}

注意：@within注解用于在类上加自定义注解，@annotation注解用于在方法上加自定义注解
在持久层mapper接口上加上自定义注解

@Mapper
@DS(value = "slave")
public interface OrdersMapper {

    Orders getOrdersById(Long id);
}

后记

自己整合实现多数据源多有麻烦，baomidou提供的dynamic-datasource-spring-boot-starter已实现了上述功能，只需要引入该依赖即可，可以参阅SpringBoot整合dynamic-datasource实现动态切换多数据源