Mybatis注入多数据源并动态切换的一种方法

2018-04-19

Mybatis注入多数据源并动态切换的一种方法

当我们需要分库分表分兼容多个mysql集群的时候，如果不使用相应的中间件，也可以使用spring自带的动态切换数据源的抽象类来达到这个目的。

step1：创建一个定义多数据源枚举待用

/**
 * Description: provide for mybatis-test-space.
 *
 * @author William.He
 * @version 1.0
 * @since 2018/4/18 17:55
 */
public enum DBTypeEnum {
    one("dataSource_one"), two("dataSource_two");
    private String value;

    DBTypeEnum(String value) {
        this.value = value;
    }

    public String getValue() {
        return value;
    }
}

step2：创建一个线程安全的上下文类来获取step1中的枚举值

/**
 * Description: provide for mybatis-test-space.
 *
 * @author William.He
 * @version 1.0
 * @since 2018/4/18 17:56
 */
public class DbContextHolder {

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

    /**
     * 设置数据源
     * @param dbTypeEnum 数据源枚举
     */
    public static void setDbType(DBTypeEnum dbTypeEnum) {
        contextHolder.set(dbTypeEnum.getValue());
    }

    /**
     * 取得当前数据源
     *
     * @return 数据源枚举值，对应targetDataSources的key
     */
    static String getDbType() {
        return contextHolder.get();
    }

    /**
     * 清除上下文数据,即清空数据源
     */
    public static void clearDbType() {
        contextHolder.remove();
    }
}

step3：创建一个动态数据源继承自spring的动态数据源抽象类,并获取到相应的数据源枚举值

/**
 * Description: provide for mybatis-test-space.
 * 动态切换数据源
 * @author William.He
 * @version 1.0
 * @since 2018/4/18 17:53
 */
public class DynamicDataSource extends AbstractRoutingDataSource {

    /**
     * 取得当前使用哪个数据源
     * @return datasource bean
     */
    @Override
    protected Object determineCurrentLookupKey() {
        return DbContextHolder.getDbType();
    }
}

step4：将step3的动态数据源注入到mybatis初始化sqlSessionFactoryBean中，这里采用的是MP的注入方式

/**
 * Description: provide for mybatis-test-space.
 *
 * @author William.He
 * @version 1.0
 * @since 2018/4/17 15:37
 */
@Configuration
@MapperScan(basePackages = {"com.pax.dal.dao"})//扫描接口
public class MybatisPlusConfig {

    @Resource(name = "dataSource")
    private DataSource dataSource;

    @Resource(name = "dataSource2")
    private DataSource dataSource2;

//    @Resource(name = "dynamicDataSource")
//    private DynamicDataSource dynamicDataSource;

    @Bean("mybatisSqlSession")
    public SqlSessionFactory sqlSessionFactory(DynamicDataSource dynamicDatasource, ResourceLoader resourceLoader, GlobalConfiguration globalConfiguration) throws Exception {
        MybatisSqlSessionFactoryBean sqlSessionFactory = new MybatisSqlSessionFactoryBean();
        sqlSessionFactory.setDataSource(dynamicDatasource);//Dynamic动态的
        sqlSessionFactory.setTypeAliasesPackage("com.pax.dal.dao");//扫描model类
        //获取自定义mapper文件的位置
        sqlSessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:com.pax.dal.sqlMapper/*.xml"));
        MybatisConfiguration configuration = new MybatisConfiguration();
        configuration.setDefaultScriptingLanguage(MybatisXMLLanguageDriver.class);
        configuration.setJdbcTypeForNull(JdbcType.NULL);
        sqlSessionFactory.setConfiguration(configuration);
        sqlSessionFactory.setPlugins(new Interceptor[]{
//                new PaginationInterceptor(),
                //性能分析，慢查询报警
                new PerformanceInterceptor(),
                //乐观锁
                new OptimisticLockerInterceptor(),
                //分页插件，源生通用的
                pageInterceptor()
        });
        sqlSessionFactory.setGlobalConfig(globalConfiguration);
        return sqlSessionFactory.getObject();
    }

    @Bean
    public GlobalConfiguration globalConfiguration() {
        GlobalConfiguration conf = new GlobalConfiguration(new LogicSqlInjector());
        conf.setLogicDeleteValue("-1");
        conf.setLogicNotDeleteValue("1");
        //全局主键默认类型，优先级次于@tableid注解
        conf.setIdType(2);
        //下划线支持
        conf.setDbColumnUnderline(true);
//        conf.setMetaObjectHandler(new H2MetaObjectHandler());//meta元
        return conf;
    }
    
    @Bean
    private DynamicDataSource dynamicDataSource(){
        DynamicDataSource control = new DynamicDataSource();
        control.setDefaultTargetDataSource(dataSource);
        Map<Object,Object> targetDataSources = new HashMap<>();
        targetDataSources.put("dataSource_one",dataSource);
        targetDataSources.put("dataSource_two",dataSource2);
        control.setTargetDataSources(targetDataSources);
        return control;
    }
    
    private PageInterceptor pageInterceptor() {
        PageInterceptor pageInterceptor = new PageInterceptor();
        Properties properties = new Properties();
        properties.put("helperDialect", "mysql");
        pageInterceptor.setProperties(properties);
        return pageInterceptor;
    }

step5：事务管理中的动态数据源同样使用step3创建的动态数据源注入

@Bean(name = "txManager")
    public DataSourceTransactionManager dataSourceTransactionManager(DynamicDataSource dynamicDatasource) {
        DataSourceTransactionManager dataSourceTransactionManager = new DataSourceTransactionManager();
        dataSourceTransactionManager.setDataSource(dynamicDatasource);
        return dataSourceTransactionManager;
    }

finally：配置的细节需要自己丰富，除此之外，就请愉快的使用吧，

使用 Demo：

@Test
   public void testMysql(){
       //切换数据源
       DbContextHolder.setDbType(DBTypeEnum.one);
       //System.out.println(pax);
       //int i = pax.deleteByAutoId(7);
       List<User> users = pax.selectList(new EntityWrapper<User>());
       System.out.println(users);
   }