集成mybaties_plus 的多数据源

要集成MyBatis-Plus的多数据源，可以按照以下步骤进行：

1. 在pom.xml中添加MyBatis-Plus和Druid的依赖。

<dependencies>
    <dependency>
        <groupId>com.baomidou</groupId>
        <artifactId>mybatis-plus-boot-starter</artifactId>
        <version>{version}</version>
    </dependency>
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid-spring-boot-starter</artifactId>
        <version>{version}</version>
    </dependency>
</dependencies>

2. 配置application.yml文件，添加多数据源的配置。

spring:
  datasource:
    dynamic:
      primary: ds1
      datasource:
        ds1:
          driver-class-name: com.mysql.jdbc.Driver
          url: jdbc:mysql://localhost:3306/ds1?useUnicode=true&characterEncoding=utf-8&useSSL=false
          username: root
          password: root
        ds2:
          driver-class-name: com.mysql.jdbc.Driver
          url: jdbc:mysql://localhost:3306/ds2?useUnicode=true&characterEncoding=utf-8&useSSL=false
          username: root
          password: root

3. 创建MyBatis-Plus的多数据源配置类。

@Configuration
public class MultiDataSourceConfig {
    @Bean
    @ConfigurationProperties("spring.datasource.dynamic.ds1")
    public DataSource ds1() {
        return DruidDataSourceBuilder.create().build();
    }

    @Bean
    @ConfigurationProperties("spring.datasource.dynamic.ds2")
    public DataSource ds2() {
        return DruidDataSourceBuilder.create().build();
    }

    @Bean
    public DataSourceRouting dataSourceRouting(@Qualifier("ds1") DataSource ds1, @Qualifier("ds2") DataSource ds2) {
        Map<Object, Object> targetDataSources = new HashMap<>();
        targetDataSources.put("ds1", ds1);
        targetDataSources.put("ds2", ds2);

        DataSourceRouting dataSourceRouting = new DataSourceRouting();
        dataSourceRouting.setTargetDataSources(targetDataSources);
        dataSourceRouting.setDefaultTargetDataSource(ds1);

        return dataSourceRouting;
    }

    @Bean
    public SqlSessionFactory sqlSessionFactory(DataSourceRouting dataSourceRouting) throws Exception {
        MybatisSqlSessionFactoryBean sqlSessionFactory = new MybatisSqlSessionFactoryBean();
        sqlSessionFactory.setDataSource(dataSourceRouting);
        sqlSessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:mapper/**/*.xml"));
        sqlSessionFactory.setGlobalConfig(globalConfiguration());

        return sqlSessionFactory.getObject();
    }

    @Bean
    public GlobalConfig globalConfiguration() {
        GlobalConfig globalConfig = new GlobalConfig();
        globalConfig.setDbType(DbType.MYSQL);
        globalConfig.setSqlInjector(new MybatisPlusSqlInjector());
        globalConfig.setMetaObjectHandler(new CustomMetaObjectHandler());

        return globalConfig;
    }
}

4. 创建一个DataSourceRouting类，用于根据不同的数据源进行路由。

public class DataSourceRouting extends AbstractRoutingDataSource {
    @Override
    protected Object determineCurrentLookupKey() {
        return DataSourceContextHolder.get();
    }
}

5. 创建一个数据源上下文类，用于在不同线程中切换数据源。

public class DataSourceContextHolder {
    private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();

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

    public static String get() {
        return contextHolder.get();
    }

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

6. 在需要切换数据源的地方，调用DataSourceContextHolder.set方法进行切换。

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserMapper userMapper;

    @Override
    public User getUserById(Integer id) {
        DataSourceContextHolder.set("ds2");
        User user = userMapper.selectById(id);
        DataSourceContextHolder.clear();

        return user;
    }
}

这样就可以实现MyBatis-Plus的多数据源配置了。