/** * 增强Mapper处理总入口：Mapper被mybatis初始化后，在这里做进一步的处理和增强 * * @author qigong on 5/1/15 */public class MapperShardingInitializer implements ApplicationContextAware { Logger logger = LoggerFactory.getLogger(getClass()); private String needEnhancedClasses; private String[] needEnhancedClassesArray; @Override public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { Map
    
      sqlSessionFactories = applicationContext.getBeansOfType(SqlSessionFactory.class); if (sqlSessionFactories.isEmpty()) { return; } MapperHelperForSharding mapperHelperForSharding = new MapperHelperForSharding(); List
     
       sqlSessions = new ArrayList<>(sqlSessionFactories.size()); for (SqlSessionFactory sqlSessionFactory : sqlSessionFactories.values()) { SqlSession sqlSession = new SqlSessionTemplate(sqlSessionFactory); sqlSessions.add(sqlSession); } //Mapper代码增强 每个方法扩展出一个ShardingMapper类，增强为512个方法。        this.needEnhancedClassesArray = needEnhancedClasses.split(","); this.enhanceMapperClass(); mapperHelperForSharding.setMappers(needEnhancedClassesArray); mapperHelperForSharding.setSqlSessions(sqlSessions.toArray(new SqlSession[0])); mapperHelperForSharding.initMapper(); } private void enhanceMapperClass() { for (String mapperClass : needEnhancedClassesArray) { try { MapperEnhancer.enhanceMapperClass(mapperClass); } catch (Exception e) { logger.error("Enhance {} class error", mapperClass, e); } } } public void setNeedEnhancedClasses(String needEnhancedClasses) { this.needEnhancedClasses = needEnhancedClasses; } }
     
    

 

3.1 this.enhanceMapperClass();

　　

/** * 对mapper进行增强，生成新的mapper，并主动加载新mapper类到classloader * * @param mapperClassName */    public static void enhanceMapperClass(String mapperClassName) throws Exception { //com.mogujie.service.tsharding.mapper.ShopOrderMapper        Class originClass = Class.forName(mapperClassName);//获取A        Method[] originMethods = originClass.getDeclaredMethods();//获取A的方法， CtClass cc = pool.get(mapperClassName);//获取到class定义的容器ClassPool，通过它获取已经编译好的类A        for (CtMethod ctMethod : cc.getDeclaredMethods()) {
   //遍历A的所有方法            CtClass enhanceClass = pool.makeInterface(mapperClassName + "Sharding" + ctMethod.getName());//针对A的每一个方法新建一个接口B //com.mogujie.service.tsharding.mapper.ShopOrderMapperShardinggetShopOrderByShopOrderId            for (long i = 0L; i < 512; i++) {
   //生成512个方法                CtMethod newMethod = new CtMethod(ctMethod.getReturnType(), ctMethod.getName() + ShardingCaculator.getNumberWithZeroSuffix(i), ctMethod.getParameterTypes(), enhanceClass); //CtMethod 和CtConstructor 提供了 insertBefore()、insertAfter()和 addCatch()方法，它们可以插入一个souce文本到存在的方法的相应的位置                Method method = getOriginMethod(newMethod, originMethods);//获取A的方法                if(method.getParameterAnnotations()[0].length > 0) {
   //如果带注解                    ClassFile ccFile = enhanceClass.getClassFile(); ConstPool constPool = ccFile.getConstPool(); //拷贝注解信息和注解内容，以支持mybatis mapper类的动态绑定 newMethod.getMethodInfo().addAttribute(MapperAnnotationEnhancer.duplicateParameterAnnotationsAttribute(constPool, method)); } enhanceClass.addMethod(newMethod);//B增加方法 } Class
     loadThisClass = enhanceClass.toClass(); //2015.09.22后不再输出类到本地            enhanceClass.writeFile("."); } }

　　需要增强的类

@DataSourceRouting(handler=TShardingRoutingHandler.class) public abstract interface ShopOrderMapper { @ShardingExtensionMethod(type=MapperResourceEnhancer.class, method="enhancedShardingSQL") public abstract ShopOrder getShopOrderByShopOrderId(@ShardingOrderPara Long paramLong); @ShardingExtensionMethod(type=MapperResourceEnhancer.class, method="enhancedShardingSQL") public abstract List
    
      getShopOrderByShopOrderIds(@ShardingOrderPara List
     
       paramList); @ShardingExtensionMethod(type=MapperResourceEnhancer.class, method="enhancedShardingSQL") public abstract int batchUpdateShopOrderByShopOrderIds(@ShardingOrderPara @Param("shopOrderIds") List
      
        paramList, @Param("shopOrder") ShopOrder paramShopOrder); }
      
     
    

增强后针对每一个方法都生成了一个类

public abstract interface ShopOrderMapperShardingbatchUpdateShopOrderByShopOrderIds { public abstract int batchUpdateShopOrderByShopOrderIds0000(@ShardingOrderPara("orderId") @Param("shopOrderIds") List paramList, @Param("shopOrder") ShopOrder paramShopOrder); public abstract int batchUpdateShopOrderByShopOrderIds0001(@ShardingOrderPara("orderId") @Param("shopOrderIds") List paramList, @Param("shopOrder") ShopOrder paramShopOrder); public abstract int batchUpdateShopOrderByShopOrderIds0002(@ShardingOrderPara("orderId") @Param("shopOrderIds") List paramList, @Param("shopOrder") ShopOrder paramShopOrder); public abstract int batchUpdateShopOrderByShopOrderIds0003(@ShardingOrderPara("orderId") @Param("shopOrderIds") List paramList, @Param("shopOrder") ShopOrder paramShopOrder); public abstract int batchUpdateShopOrderByShopOrderIds0004(@ShardingOrderPara("orderId") @Param("shopOrderIds") List paramList, @Param("shopOrder") ShopOrder paramShopOrder);

public abstract interface ShopOrderMapperShardinggetShopOrderByShopOrderId { public abstract ShopOrder getShopOrderByShopOrderId0000(@ShardingOrderPara("orderId") Long paramLong); public abstract ShopOrder getShopOrderByShopOrderId0001(@ShardingOrderPara("orderId") Long paramLong); public abstract ShopOrder getShopOrderByShopOrderId0002(@ShardingOrderPara("orderId") Long paramLong); public abstract ShopOrder getShopOrderByShopOrderId0003(@ShardingOrderPara("orderId") Long paramLong); public abstract ShopOrder getShopOrderByShopOrderId0004(@ShardingOrderPara("orderId") Long paramLong); public abstract ShopOrder getShopOrderByShopOrderId0005(@ShardingOrderPara("orderId") Long paramLong); public abstract ShopOrder getShopOrderByShopOrderId0006(@ShardingOrderPara("orderId") Long paramLong); public abstract ShopOrder getShopOrderByShopOrderId0007(@ShardingOrderPara("orderId") Long paramLong); }

public abstract interface ShopOrderMapperShardinggetShopOrderByShopOrderIds { public abstract List getShopOrderByShopOrderIds0000(@ShardingOrderPara("orderId") List paramList); public abstract List getShopOrderByShopOrderIds0001(@ShardingOrderPara("orderId") List paramList); public abstract List getShopOrderByShopOrderIds0002(@ShardingOrderPara("orderId") List paramList); public abstract List getShopOrderByShopOrderIds0003(@ShardingOrderPara("orderId") List paramList); public abstract List getShopOrderByShopOrderIds0004(@ShardingOrderPara("orderId") List paramList); public abstract List getShopOrderByShopOrderIds0005(@ShardingOrderPara("orderId") List paramList); public abstract List getShopOrderByShopOrderIds0006(@ShardingOrderPara("orderId") List paramList); public abstract List getShopOrderByShopOrderIds0007(@ShardingOrderPara("orderId") List paramList); }

 

3.2 mapperHelperForSharding.setMappers(needEnhancedClassesArray);

　　通过ShopOrderMapper.java，获取注解配置 @ShardingExtensionMethod(type = MapperResourceEnhancer.class, method = "enhancedShardingSQL")， 　　生成MapperEnhancer，以ShopOrderMapper的方法名为key,MapperResourceEnhancer.enhancedShardingSQL 为value,保存在MapperResourceEnhancer.methodMap中。 　　返回MapperEnhancer，再以ShopOrderMappe 为key,MapperEnhancer为value,保存在MapperHelperForSharding.registerMapper中，供后续使用 3.3 mapperHelperForSharding.setSqlSessions(sqlSessions.toArray(new SqlSession[0])); 　　把sqlSession保存在mapperHelperForSharding.sqlSessions 3.4 mapperHelperForSharding.initMapper();（ Spring4 is necessary） 　　类关系:SqlSession>Configuration>MappedStatement>DynamicSqlSource||RawSqlSource 　　遍历 sqlSessions，处理Configuration中全部的MappedStatement，重新设置SqlSource。 　　重新设置SqlSource：获取MapperTemplate（3.2mapperHelperForSharding.registerMapper中保存的MapperEnhancer）。 　　然后 mapperEnhancer.setSqlSource(ms, configuration);代码增强 扩充为512个方法。 

　　

public void setSqlSource(MappedStatement ms, Configuration configuration) throws Exception { Method method = methodMap.get(getMethodName(ms));//3.2中保存的enhancedShardingSQL方法                    try { if (method.getReturnType() == Void.TYPE) { method.invoke(this, ms); } else if (SqlSource.class.isAssignableFrom(method.getReturnType())) { //代码增强 扩充为512个方法。                            for (long i = 0; i < 512; i++) { //新的带sharding的sql                                SqlSource sqlSource = (SqlSource) method.invoke(this, ms, configuration, i); String newMsId = ms.getId() + ShardingCaculator.getNumberWithZeroSuffix(i); newMsId = newMsId.replace("Mapper.", "MapperSharding" + getMethodName(ms) + "."); //添加到ms库中                                MappedStatement newMs = copyFromMappedStatement(ms, sqlSource, newMsId); configuration.addMappedStatement(newMs); setSqlSource(newMs, sqlSource); } } else { throw new RuntimeException("自定义Mapper方法返回类型错误,可选的返回类型为void和SqlNode!"); } } catch (IllegalAccessException e) { throw new RuntimeException(e); } catch (InvocationTargetException e) { throw new RuntimeException(e.getTargetException() != null ? e.getTargetException() : e); } }

 

3.4.1 SqlSource sqlSource = (SqlSource) method.invoke(this, ms, configuration, i);

　　实际调用com.mogujie.trade.tsharding.route.orm.MapperResourceEnhancer;enhancedShardingSQL 　　  （SqlSession>Configuration>MappedStatement>DynamicSqlSource||RawSqlSource） 　　 　　DynamicSqlSource中存在mapperxml中每个节点的语句。 　　　    awSqlSource中存在mapperxml中的sql语句。根据分片参数替换成对应的表名，比如TradeOrder0066 　　　　最终生成的sql语句类似(SELECT orderId, buyerUserId,sellerUserId FROM TradeOrder0066 WHERE orderId = ? limit 1) 　　用新ID，创建MappedStatement（mapperxml节点），添加到Configuration，设置数据源 　　　　 新ID格式：com.mogujie.service.tsharding.mapper.ShopOrderMapperShardinggetShopOrderByShopOrderId.getShopOrderByShopOrderId0000