The technical principles and applications of the persistent API framework in the Java class library
The technical principles and applications of the persistent API framework in the Java class library
In Java development, persistence refers to preserving data in persistent storage medium so that the data status can still be retained after the program is closed or restarted.The persistent API framework provides a simple and powerful way to perform persistent operations. It allows developers to save the object directly into the database or other storage media without writing a large number of underlying database operation code.
Common Java persistence API frameworks include Hibernate, Spring Data JPA and MyBatis.These frameworks have different characteristics and application scenarios, but they all provide developers with high -efficiency and easy -to -use persistence solutions through packaging database operation details.
Hibernate is a widely used object relationship mapping (ORM) framework. It maps the Java object and the database table to realize the conversion between the object and the relationship.Hibernate uses XML or annotation to define the mapping relationship between objects and database tables, and provides a set of APIs to perform database operations, such as saving, updating, querying and deleting.Developers only need to write simple POJO (PLAIN OELD JAVA Object) class and some configuration files to achieve persistent operations of the object.
Spring Data JPA is a sub -project in the Spring framework. It encapsulates the JPA (Java Persistence API) standard, providing developers with a more concise and more convenient and persistent way.JPA is a set of API defined in the Java EE platform to process the persistence of objects and database access.By using the Spring Data JPA, developers only need to define one interface and inherit some interfaces provided by Spring Data JPA, which can achieve basic CRUD operation without writing specific implementation code.Spring Data JPA simplifies database access by automatically creation query and method name query.
MyBatis is an excellent persistence framework that separates the SQL statement from Java code and configure files or annotations for database operations.MyBatis provides a set of powerful SQL mapping functions. Developers can write complex SQL statements and map it into the Java method.Compared with Hibernate and Spring Data JPA, MyBatis is closer to traditional SQL programming methods to better control the execution of SQL statements.
The following is a simple example code that shows how to use Hibernate for the persistent operation of the object:
@Entity
@Table(name = "users")
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column(name = "username")
private String username;
@Column(name = "password")
private String password;
// omit the constructive method, getter and setter
}
public class Main {
public static void main(String[] args) {
User user = new User();
user.setUsername("admin");
user.setPassword("123456");
SessionFactory sessionFactory = new Configuration()
.configure()
.buildSessionFactory();
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
session.save(user);
transaction.commit();
session.close();
sessionFactory.close();
}
}
In the above code, we define a User class and map it to the database table by annotation.In the main method, we created a sessionFactory object of Hibernate, and then open a new Session through SessionFactory.With the support of transactions, we saved the User object into the database and submitted the affairs.Finally, we closed session and sessionFactory.
In this way, we can simply and efficiently use Hibernate for the persistence of objects.At the same time, Hibernate provides a rich query API and cache mechanism, which can further improve performance and scalability.
In summary, the persistent API framework in the Java library provides simple and efficient persistence solutions.Developers can choose a suitable framework based on project needs and personal preferences. By using these frameworks, they can greatly simplify database operations and improve development efficiency.
