Spring 3 - 基于另一个对象属性的运行时动态自动装配 [英] Spring 3 - Dynamic Autowiring at runtime based on another object attribute

问题描述

我正在使用Spring 3.1 MVC应用程序，而对于我的一个场景，我不得不编写一个DAO的两个实现。我想知道如何基于另一个对象的属性在一个服务层
中自动连接。

例如，

  class Vehicle {
 private name; 
私有类型; 
 .. 
 .. 
 .. 
} 
 
 @Service 
 class VehicleServiceImpl实现VehicleService {
 
 //这个DAO 
有两个实现//如果Vehicle.type ==CAR，注入CarDAO 
 //如果Vehicle.type ==TRAIN，则注入TrainDAO 
 @自动连线
私人车辆
 
} 
 
 @Repository 
 class CarDAO实现VehicleDAO {
 
} 
 
 @Repository 
类TrainDAO实施车辆代码{
 
} 
  

如果我的车是一辆车我需要自动连线CarDAO，如果是火车，我需要自动连线TrainDAO

在春季3.1中实现这一点的最好方法是什么？

我希望使用上下文属性占位符或@Qualifier注释，但这两种都是基于某些属性进行查找的限制。
我不知道如何在运行时基于另一个对象的属性来执行此操作。

解决方案

我的解决方案将如下所示：

一个方法isResponsibleFor在VehicleDao界面中：

 界面VehicleDao {
 public boolean isResponsibleFor（Vehicle vehicle）; 
} 
  

示例实现：

  @Repository 
 class CarDAO实现了VehicleDAO {
 public boolean isResponsibleFor（Vehicle vehicle）{
 returnCAR.equals（vehicle.getType（） ）; 
} 
} 
  

然后autowire a 车辆服务：

  public class VehicleServiceImpl实现VehicleService {
 
 @Autowired 
 private List& VehicleDao> vehicleDaos; 
 
私人车辆DaoForVehicle（车辆车辆）{
 foreach（VehicleDao vehicleDao：vehicleDaos）{
 if（vehicleDao.isResponsibleFor（vehicle）{
 return vehicleDao; 
 $ 
 
 
 throw new UnsupportedOperationException（unsupported vehicleType）; 
} 
 
 @Transactional 
 public void save车辆）{
 daoForVehicle（车辆）.save（车辆）; 
} 
} 
  

这样做的好处是，您在以后添加新的车辆类型时不需要修改服务 - 您只需要添加一个新的VehicleDao实现。

I am working on a Spring 3.1 MVC application and for one of my scenarios, I had to write two implementations of a DAO. I would like to know how to autowire this in a service layer based on another object's attribute.

For example,

    class Vehicle {
        private name;
        private type;
        ..
        ..
        ..
    } 

    @Service
    class VehicleServiceImpl implements VehicleService {

            // There are two implementations to this DAO
            // if Vehicle.type == "CAR", inject CarDAO
            // if Vehicle.type == "TRAIN", inject TrainDAO 
            @Autowired
            private VehicleDAO vehicleDAO ;

    }

    @Repository
    class CarDAO implements VehicleDAO {

    }

    @Repository
    class TrainDAO implements VehicleDAO {

    }

If my Vehicle is a Car, I need to autowire CarDAO and if it's a train, I need to autowire TrainDAO

What is the best way to implement this in spring 3.1.

I was hoping to use either context property place holders or @Qualifier annotation but both these are kind of restricted to lookup based on some property. I am not sure how to do this at runtime based on the property of another object.

解决方案

My solution would be as follows:

a method isResponsibleFor in the VehicleDao interface:

interface VehicleDao {
    public boolean isResponsibleFor(Vehicle vehicle);
}

example implementation:

@Repository
class CarDAO implements VehicleDAO {
    public boolean isResponsibleFor(Vehicle vehicle) {
        return "CAR".equals(vehicle.getType());
    }
}

then autowire a list of all VehicleDao-implementations in the VehicleService:

public class VehicleServiceImpl implements VehicleService {

    @Autowired
    private List<VehicleDao> vehicleDaos;

    private VehicleDao daoForVehicle(Vehicle vehicle) {
         foreach(VehicleDao vehicleDao : vehicleDaos) {
              if(vehicleDao.isResponsibleFor(vehicle) {
                   return vehicleDao;
              }
         }

         throw new UnsupportedOperationException("unsupported vehicleType");
    }

    @Transactional
    public void save(Vehicle vehicle) {
         daoForVehicle(vehicle).save(vehicle);
    }
}

This has the advantage that you don't need to modify the service when you are adding a new vehicleType at a later time - you just need to add a new VehicleDao-implementation.

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