Spring and Hibernate Operations

Question

I'm new to Spring, and I just read the docs on Hibernate-Spring integration (version 3). I don’t understand why automatic transaction management (declarative) is applied to the “service” in the documents, and not to the DAO implementation directly. In particular, I do not understand what they mean for the service, what is the difference compared to the DAO, and if it is really necessary for integrating Hibernate with Spring.

I tried using only the Hibernate DAO Implementation and configured in XML so that the factory session would be established after the instance was created. In any case, this throws exceptions, since Spring does not allow access to transactional hibernation. So, to add transactional access, do I need to add this "service"? How is this different from a simple DAO?

Answer 1

A DAO (Data Access Object) is just a design pattern or the name of the class that implements this pattern.

Service is a (Spring) term for (most single-user) classes that provides some (business) service functions. And this is also the annotation name for declaring a class as a service in Spring.

fixed: repository instead of resource

There are many ways to implement DAO in spring, most of two common shares:

• Using spring Hibernate Template Class (deprecated in spring 3.0)
• , DAO @Repository ( @Service, @ @ @))

Answer 2

Spring, :

, , , DAO

" ", . "" ( ), : A, B. , . , .

:

transfer(Account to, Account from, double value)

DAO :

updateBalance(Account account, double amount)

transfer updateBalance, .

Spring, , ( ) Spring , , .

Answer 3

DAO . , , , . , - -.

-. , . . , . , , . , /, , . , DAO.

Answer 4

, DAO. , , , , DAO, . (, SQL, .)

DAO ( , , , DAO, ), DTO.

Transactional services and the DAO can work fine with each other as long as the distribution of transactions in the DAO is properly set. That is, use an existing transaction if it exists, but create a new one if it does not.