Spring Java中许多DAO的策略 [英] Strategy for many DAOs in Spring Java

问题描述

我们在现有项目中有许多DAO(当前没有接口，但是可以更改).我们没有为每个DAO类连接一个Spring管理的Bean并将它们注入服务层，而是有一个DAO的工厂"，其形式如下:

public class DAOFactory {
private static DAOFactory daoFac;

static{
    daoFac = new DAOFactory();
}

private DAOFactory(){}

public static DAOFactory getInstance(){
    return daoFac;
}

public MyDAO1 getMyDAO1(){
    return new MyDAO1();
}

    public MyDAO2 getMyDAO2(){
    return new MyDAO2();
}
    ...

(请注意，MyDAO1和MyDAO2是具体的类)

这使我们能够轻松地在Service层中添加/调用DAO方法，而不必1.)将DAO接口作为属性添加到服务类中； 2.)通过配置将DAO实现连接到服务方法中. (而且我们有时在一个服务类中使用多个DAO).

DAOFactory.getInstance().getMyDAO1().doSomething();

到目前为止，该策略对我们一直有效(我们并不需要太多切换实现)，但是我想知道是否有更好的方法可以启动新的?我将DAO作为Bean进行自动装配，但是我仍然需要在每个服务类中创建属性以表示所使用的DAO.在一个大型项目中，无论如何我还是很犹豫是否开始自动装配bean-我们需要为所有开发人员提供可见性.

感觉就像我在a.)紧密耦合到一个实现，但是更少的代码/配置开销和b.)松散耦合到接口，但是需要大量的代码/配置开销之间进行翻转./p>

有没有更好的方法让我丢失?介于两者之间?欢迎意见.

解决方案

我将把所有DAO都作为Spring托管的组件，并将它们注入服务中以进行松散耦合.为什么您认为在大型项目中自动装配bean不好??

只需使用@Component注释每个DAO类 并将MyDao mydao = factory.getmyDao()替换为

@Autowired MyDao myDao;

我没有看到太多的编码/配置开销.

We have many DAOs in an existing project (currently with no interfaces, but that can change). Rather than wiring a Spring-managed bean for each DAO class and injecting them into the service layer, we have a DAO "factory" of sorts that looks like this:

public class DAOFactory {
private static DAOFactory daoFac;

static{
    daoFac = new DAOFactory();
}

private DAOFactory(){}

public static DAOFactory getInstance(){
    return daoFac;
}

public MyDAO1 getMyDAO1(){
    return new MyDAO1();
}

    public MyDAO2 getMyDAO2(){
    return new MyDAO2();
}
    ...

(Note that MyDAO1 and MyDAO2 are concrete classes)

This allows us to easily add/call DAO methods within the Service layer, without having to 1.) add a DAO interface as a property to the service class 2.) wire the DAO implementation into service method via configuration. (And we sometimes use multiple DAOs in one service class).

DAOFactory.getInstance().getMyDAO1().doSomething();

This strategy has worked for us so far (we haven't had much need for switching implementations), but I'm wondering if there is a better method if we were able to start new? I looked at autowiring the DAOs as beans, but I'd still need to create properties in each service class to represent those DAOs being used. And in a large project, I'm hesitant to start auto-wiring beans anyway - we need to provide visibility for all developers.

It feels like I'm flip-flopping between a.) being tightly-coupled to an implementation, but less code/config overhead and b.) being loosely coupled to interfaces, but requiring plenty of code/configuration overhead.

Is there a better way I'm missing? Something in-between? Opinions welcomed.

解决方案

I will have all the DAO s as Spring managed components and inject them into services for loose coupling. Why do you think autowiring beans is bad in a big project.?

Just annotate each DAO class with @Component and replace MyDao mydao = factory.getmyDao() with

@Autowired MyDao myDao;

I dont see much coding/configuration overhead with it.

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