Springboot dynamically switches data sources

Springboot dynamically switches data sources

1. Introduce Alibaba's druid component

      <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.3</version>
        </dependency>
           <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>transmittable-thread-local</artifactId>
            <version>2.2.0</version>
        </dependency>

2. In the yml file of the spring project, add the database information. My project has added the taos database. Of course, bloggers can remove it.

spring:
  datasource:
    tdengine-server:
      jdbc-url: jdbc:TAOS://127.0.0.1:6030/valid_time?timezone=Asia/Shanghai&charset=utf-8
      driver-class-name: com.taosdata.jdbc.TSDBDriver
      username: root
      password: taosdata
  druid:
    datasource:
      master:
        jdbc-url: jdbc:mysql://127.0.0.1:3306/valid_project?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true&useSSL=false&serverTimezone=Asia/Shanghai
        driver-class-name: com.mysql.jdbc.Driver
        username: root
        password: Shutd0wn
      slave:
        jdbc-url: jdbc:mysql://127.0.0.1:3306/valid_project_test?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true&useSSL=false&serverTimezone=Asia/Shanghai
        driver-class-name: com.mysql.jdbc.Driver
        username: root
        password: Shutd0wn

3. Create the DataSourceProperties class

@ConfigurationProperties(prefix = "spring.druid.datasource")
@Component
@Getter
@Setter
public class DataSourceProperties {
    
    
    private Map<String,String> master;
    private Map<String,String> slave;
}

4. Create a data source switching configuration class DynamicDataSourceConfig

@Configuration
@MapperScan(basePackages = {
    
    "com.sinux.sinuxproject.dao.mysql"})
public class DynamicDataSourceConfig {
    
    
    @Resource
    private DataSourceProperties dataSourceProperties;
    @Bean
    public DataSource master(@Autowired DataSourceProperties dataSourceProperties){
    
    
        DruidDataSource druidDataSource = new DruidDataSource();
        Map<String, String> master = dataSourceProperties.getMaster();
        druidDataSource.setUsername(master.get("username"));
        druidDataSource.setPassword(master.get("password"));
        druidDataSource.setUrl(master.get("jdbc-url"));
        //其他参数配置 省略
        return druidDataSource;
    }

    @Bean
    public DataSource slave(@Autowired DataSourceProperties dataSourceProperties){
    
    
        DruidDataSource druidDataSource = new DruidDataSource();
        Map<String, String> slave = dataSourceProperties.getSlave();
        druidDataSource.setUsername(slave.get("username"));
        druidDataSource.setPassword(slave.get("password"));
        druidDataSource.setUrl(slave.get("jdbc-url"));
        //其他参数配置 省略
        return druidDataSource;
    }

    @Bean("dataSource")
    @Primary
    public DynamicDataSource dataSource(DataSource master,DataSource slave){
    
    
        Map<Object,Object>map = new HashMap<>(4);
        map.put("master",master);
        map.put("slave",slave);
        return new DynamicDataSource(master,map);
    }
    @Primary
    @Bean("sqlSessionFactoryBean")
    public SqlSessionFactory sqlSessionFactoryBean(@Qualifier("dataSource") DynamicDataSource dynamicDataSource) throws Exception {
    
    
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dynamicDataSource);
        sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:mapper/mysql/**/*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(name = "mysqlTransactionManager")
    @Primary
    public DataSourceTransactionManager mysqlTransactionManager(@Qualifier("dataSource")DynamicDataSource dynamicDataSource) {
    
    
        return new DataSourceTransactionManager(dynamicDataSource);
    }
    @Bean(name = "mysqlSqlSessionTemplate")
    @Primary
    public SqlSessionTemplate mysqlSqlSessionTemplate(@Qualifier("sqlSessionFactoryBean")SqlSessionFactory sqlSessionFactory) throws Exception {
    
    
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}

5. Create DynamicDataSource to inherit AbstractRoutingDataSource, rewrite determineCurrentLookupKey method, and realize data source switching

public class DynamicDataSource extends AbstractRoutingDataSource {
    
    
	//异步线程变量共享
    private static final TransmittableThreadLocal<String> contextHolder = new TransmittableThreadLocal<>();

    public DynamicDataSource(DataSource defaultTargetDataSource, Map<Object, Object> targetDataSources) {
    
    
        super.setDefaultTargetDataSource(defaultTargetDataSource);
        super.setTargetDataSources(targetDataSources);
        super.afterPropertiesSet();
    }


    @Override
    protected Object determineCurrentLookupKey() {
    
    
        return getDataSource();
    }

    public static void setDataSource(String dataSource) {
    
    
        contextHolder.set(dataSource);
    }

    public static String getDataSource() {
    
    
        System.out.println(contextHolder.get());
        String key = contextHolder.get()==null?"master":contextHolder.get();
        return key;
    }

    public static void clearDataSource() {
    
    
        contextHolder.remove();
    }
}

6. Exclude automatic configuration of startup classes

@SpringBootApplication(exclude= {
    
    DataSourceAutoConfiguration.class})

7. To use, you only need to switch the data source before using it. I use aop to intercept and judge

 DynamicDataSource.setDataSource("slave");