Implementation of Dynamic Switching of mybatis Multiple Data Sources in springboot

Directory multi-data source configuration introduction
Implementation of Dynamic Data Source Routing
Dynamic data source switching use
Case source code

In development, dynamic data source configuration is still used more, such as in the use of multiple data sources, or switching between multiple DB. Here is a configuration scheme of a dynamic data source, and both DB take mysql as an example.

Introduction of multiple data source configuration

The introduction of mybatis and mysql in springboot will not be mentioned here. If you don't understand it, please refer to the introduction of mysql and mybatis in springboot.

The data source configuration is as follows:

datasource:
  master:
    type: com.alibaba.druid.pool.DruidDataSource
    jdbc-url: jdbc:mysql://127.0.0.1:3306/sbac_master?autoReconnect=true&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true
    username: root
    password: 1234
    driver-class-name: com.mysql.cj.jdbc.Driver
  log:
    type: com.alibaba.druid.pool.DruidDataSource
    jdbc-url: jdbc:mysql://127.0.0.1:3306/sbac_log?autoReconnect=true&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true
    username: root
    password: 1234
    driver-class-name: com.mysql.cj.jdbc.Driver

The configuration of mybatis is introduced as follows:

mybatis:
  config-location: classpath:mybatis-config.xml
  mapper-locations: classpath:com/lazycece/sbac/mysql/data/dao/*/mapper/*.xml

The mybatis information has been configured using springboot's auto-configuration functionality, only manually specifying the data source. As shown below, two data sources, master and log, are specified, and master is set as the default data source:

@Configuration
public class MultiDataSource {

    public static final String MASTER_DATA_SOURCE = "masterDataSource";
    public static final String LOG_DATA_SOURCE = "logDataSource";

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

    @Bean(name = MultiDataSource.LOG_DATA_SOURCE)
    @ConfigurationProperties(prefix = "datasource.log")
    public DataSource logDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Primary
    @Bean(name = "dynamicDataSource")
    public DynamicDataSource dataSource() {
        DynamicDataSource dynamicDataSource = new DynamicDataSource();
        dynamicDataSource.setDefaultTargetDataSource(masterDataSource());
        Map<Object, Object> dataSourceMap = new HashMap<>(4);
        dataSourceMap.put(MASTER_DATA_SOURCE, masterDataSource());
        dataSourceMap.put(LOG_DATA_SOURCE, logDataSource());
        dynamicDataSource.setTargetDataSources(dataSourceMap);
        return dynamicDataSource;
    }
}

Implementation of Dynamic Data Source Routing

After the introduction of configuration information, it is time to talk about how to switch multiple data sources. We implement the determineCurrentLookupKey method of AbstractRoutingDataSource class to realize the dynamic routing of data sources, and set the ThreadLocal thread protection variable to store the data source key to ensure that threads are not affected.

package com.lazycece.sbac.mysql.multi.config;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

/**
 * @author lazycece
 */
public class DynamicDataSource extends AbstractRoutingDataSource {
    private static final Logger LOGGER = LoggerFactory.getLogger(DynamicDataSource.class);

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

    static void changeDataSource(String dataSourceKey) {
        DATA_SOURCE_KEY.set(dataSourceKey);
    }

    static void clearDataSource() {
        DATA_SOURCE_KEY.remove();
    }

    @Override
    protected Object determineCurrentLookupKey() {
        String key = DATA_SOURCE_KEY.get();
        LOGGER.info("current data-source is {}", key);
        return key;
    }
}

Then, the dynamic switching of data sources is realized by AOP. The annotations and sections are defined as follows:

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

    String value();
}

@Component
@Aspect
public class DataSourceConfig {

    @Before("@annotation(dataSource)")
    public void beforeSwitchDataSource(DataSource dataSource) {
        DynamicDataSource.changeDataSource(dataSource.value());
    }

    @After("@annotation(DataSource)")
    public void afterSwitchDataSource() {
        DynamicDataSource.clearDataSource();
    }
}

Dynamic data source switching use

Dynamic data source switching only requires the @ DataSource annotation in the business to indicate which data source to use, as shown below (only the key code is posted here):

@Service
public class DynamicDataSourceServiceImpl implements DynamicDataSourceService {

    @Resource
    private UserDao userDao;
    @Resource
    private SystemLogDao systemLogDao;

    @Override
    @DataSource(value = MultiDataSource.MASTER_DATA_SOURCE)
    public void addUserInfo(User user) {
        userDao.insert(user);
    }

    @Override
    @DataSource(value = MultiDataSource.MASTER_DATA_SOURCE)
    public User getUserInfo(String username) {
        return userDao.findByUsername(username);
    }

    @Override
    @DataSource(value = MultiDataSource.LOG_DATA_SOURCE)
    public void addSystemLog(SystemLog systemLog) {
        systemLogDao.insert(systemLog);
    }

    @Override
    @DataSource(value = MultiDataSource.LOG_DATA_SOURCE)
    public List<SystemLog> getSystemLogInfo(Date beginTime, Date endTime) {
        return systemLogDao.findByCreateTime(beginTime, endTime);
    }
}

Case source code

Case source address: https://github.com/lazycece/springboot-actual-combat/tree/springboot/ac-mysql/ac-mysql-multi