Detailed explanation of the persistence implementation of the Spring ORM framework
Detailed explanation of the persistence implementation of the Spring ORM framework
Overview:
Spring ORM is a module of the Spring framework to simplify the interaction with the database.It provides an abstract layer to establish a mapping relationship between the Java object and the database table to achieve the persistence of the object.This article will discuss the persistence implementation principle of the Spring ORM framework and provide examples of Java code to help readers better understand.
The main component of Spring ORM:
1. Session Factory: In Spring ORM, Session Factory is an important component.It is responsible for creating the session of Hibernate and establishing a connection with the database.Session Factory is safe and can be shared in multiple threads.It is also responsible for managing database connection pools, transaction management, and cache functions.
2. Hibernate: Hibernate uses Hibernate as a persistence provider in the Spring ORM framework.Hibernate is a popular open source object relationship mapping framework, which simplifies the mapping process between the Java object and the relational database.Through Hibernate, we can use object -oriented methods to operate the database without writing complex SQL statements.
3. Transaction Manager: Spring ORM manages database transactions through transaction managers.The transaction manager is responsible for coordinating the consistency of multiple data operations, and provides ACID (atomic, consistency, isolation and persistence) characteristics.Spring ORM can integrate with multiple transaction managers, such as JTA (Java Affairs API), JDBC and Hibernate transactions.
4. Data Access Objects (DAO): In Spring ORM, DAO is responsible for the specific implementation of database operations.It contains the CRUD (creation, reading, update, deletion) operation of the database and provides some advanced query methods.The DAO layer performs various database operations by calling Hibernate's API.Spring ORM encapsulates the DAO layer, allowing developers to make database operations easier.
Spring ORM's persistence implementation principle:
1. Configuration: First, configure the session faction in the Spring configuration file, that is, the related attributes of the Hibernate, such as database connection information, mapping files, etc.
2. Session Factory Creation: According to configuration information, Spring ORM creates session faction through sessionFactoryBean.SessionFactoryBean is responsible for creating the Configuration instance of Hibernate and loading the configuration information into the Configuration object.SEssionFactoryBean then used the Configuration object to create SessionFactory.
3. Session's acquisition: Where to interact with the database, obtain session through sessionFactory.The session representative and a database session can perform various database operations through it.
4. Affairs management: Spring ORM manages database transactions through transaction managers.Developers can configure the transaction manager through annotations or programming.The transaction manager will open, submit or roll back the transaction where the need is needed to ensure the consistency of the data.
5. Database operation: After obtaining session, perform database operations through DAO.The DAO layer is encapsulated with Hibernate API and provides some convenient methods to provide the ability to access the database.By calling the method of DAO, you can perform operations such as adding, deletion, modification and investigation.
6. Submission of transactions: After all database operations are completed, Spring ORM will submit the transaction according to the configuration of the transaction manager.Affairs submission will persist in the database operation into the database.
7. Rolling transaction: If an abnormality occurs or the previous database operations need to be canceled, the transaction manager will roll back the transaction and revoke all the operations of the database.
Java code example:
Suppose we have a physical class called User, corresponding to a user watch in the database.The following is a simple DAO example for operating the user table:
@Repository
public class UserDaoImpl implements UserDao {
@Autowired
private SessionFactory sessionFactory;
@Override
public User getUserById(int id) {
Session session = sessionFactory.getCurrentSession();
User user = session.get(User.class, id);
return user;
}
@Override
public void saveUser(User user) {
Session session = sessionFactory.getCurrentSession();
session.save(user);
}
@Override
public void updateUser(User user) {
Session session = sessionFactory.getCurrentSession();
session.update(user);
}
@Override
public void deleteUser(User user) {
Session session = sessionFactory.getCurrentSession();
session.delete(user);
}
}
The UserDaoimpl class in the above example code uses the @Repository annotation of Spring, indicating that it is a DAO component.Through the @AutowIRED annotation, we injected the SessionFactory instance and used it in the specific database operation method to obtain Session.By calling the session method, we can implement the database addition, deletion, and check operation.
Summarize:
This article explains the principle of the persistence implementation of the Spring ORM framework and provides a simple Java code example.By understanding the working principle of Spring ORM, we can better understand that it simplifies the interaction with the database and provides the advantages of flexible and persistent ways.By using Spring ORM, we can perform database operations faster and more efficiently.
