Implementation of dynamic switching of mybatis multiple data sources in spring boot

Time:2022-5-9

In development, dynamic data source configuration is often used, such as in the use of multiple data sources or switching between multiple DBS. Take the two dynamic data sources of MySQL as an example.

Multi data source configuration introduction

The introduction of mybatis and MySQL in springboot will not be discussed here. SeeIntroduction of MySQL and mybatis in spring boot

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 automatic configuration function of springboot is used here to configure mybatis information, but the data source is manually specified. As shown below, specify master and log data sources, and set master 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 introducing the configuration information, it is time to talk about how to realize multi data source switching. 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, AOP is used to realize the dynamic switching of data sources. The annotation and section 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

For dynamic data source switching, you only need to use @ datasource annotation in the business to indicate the data source to be used, as shown below (only key codes are pasted 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 code address:https://github.com/lazycece/springboot-actual-combat/tree/master/springboot-ac-mysql/springboot-ac-mysql-multi

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