Question

我的端到端流程如下所示：控制器->适配器->持久性/存储库-> DB

在我的控制器中：

@RequestMapping(value = "/userOrder/{orderID}", method = RequestMethod.DELETE)
   public Set<?> deleteOrder(@PathVariable("orderID") String orderID) {
   /*
    * orderHandlerAdapter cancels the order and passed list of orders created + cancelled so  * far.
    */
    Set<Orders> orderList = orderHandlerAdapter.cancelOrder(orderID);
    return orderList;
   }

在适配器中：

public Set<Order> cancelOrder(String orderID) {
/*
 * Cancel order first.
 */
    userOrderRepository.saveOrder(orderID,"CANCELLED");
/*
 * Return list of orders created and cancelled so far.
 */
    Set<Order> orderList = userOrderRepository.getFirstByOrderIdAndStatusCdIsIn(orderID, new Set<String> {"CREATED","CANCELLED"});
    return Set<Order>;
}

持续存在：

    public interface orderRespository extends CrudRepository<UserOrder,String>() {
/*
 * Save status = CANCELLED into the DB.
 */
    void saveOrder(String orderID);
    /*
     * Get orders that are created and cancelled.
     */
    Set<Order> getFirstByOrderIdAndStatusCdIsIn(String orderID, new Set<String> orderStatusSet); 
    }

我发现，当调用saveOrder / getFirstByOrderIdAndStatusCdIsInis时，查询未在任何地方定义，并且接口也未实现。但是结果可以正确返回。

这是如何工作的？ JPA是否足够智能，可以根据方法名称创建查询？

Answer 1

Spring Data has a default implementation for the methods from the repositories included in the product (CrudRepository, PagingAndSortingRepository, JpaRepository, QueryByExampleExecutor). You can find many in the SimpleJpaRepository.

But it is not just that an instance of SimpleJpaRepository gets added to the ApplicationContext. instead, a proxy is used. The proxy checks the method being called and decides how to provide an implementation:

Is it a predefined method -> call its implementation
Does it have a @Query annotation or does its name match a named query -> call that
Can its name converted into a query -> do so.

Beyond that Spring Data takes care of conversions between results of the queries and the required return type of the method.

它会自动构造查询吗

1 个答案: