Use the "Persistence API" framework to implement the persistent operation in the Java class library
Use the persistent API framework to implement the persistent operation in the Java class library
Overview:
With the advent of the era of big data, the persistence of data has become increasingly important.In Java programming, the persistent operation is to store data to the persistent storage medium so that it can be reloaded after the program is restarted.
Traditional persistent operations may involve complex database programming and SQL query.In order to simplify this process, the use of persistent API frameworks can easily perform data persistence operations, allowing developers to focus on the realization of business logic without need to care about the database details of the bottom layer.
In Java development, a common persistence API framework is using the Java Persistence API (JPA).JPA is a specification of the establishment of a mapping relationship between the Java object and the relationship database, which can easily achieve the object relationship mapping (ORM).
JPA realizes several core concepts, such as physical class, mapping relationships, persistent units and physical managers.Below we will demonstrate how to use JPA to achieve persistent operations through a simple example.
Implement example:
First of all, we need to define a physical class, which is used to maximize the table in the database.Suppose we have a physical class called "User", including ID, name, and Age attributes.The code is shown below:
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
@Entity
public class User {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String name;
private int age;
// omit the constructor, Getter, and Setter
// Other business methods
}
We then need to configure the persistent unit and create a physical manager factory.Configure in the persistence.xml file of the project, such as:::
<persistence-unit name="myPersistenceUnit" transaction-type="RESOURCE_LOCAL">
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/mydb"/>
<property name="javax.persistence.jdbc.user" value="username"/>
<property name="javax.persistence.jdbc.password" value="password"/>
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
</properties>
</persistence-unit>
Next, we can use a physical manager in the code for persistent operations.For example, we can realize a way to save user information:
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
public class UserRepository {
private EntityManagerFactory entityManagerFactory;
public UserRepository() {
entityManagerFactory = Persistence.createEntityManagerFactory("myPersistenceUnit");
}
public void saveUser(User user) {
EntityManager entityManager = entityManagerFactory.createEntityManager();
EntityTransaction transaction = entityManager.getTransaction();
try {
transaction.begin();
entityManager.persist(user);
transaction.commit();
} catch (Exception e) {
if (transaction.isActive()) {
transaction.rollback();
}
e.printStackTrace();
} finally {
entityManager.close();
}
}
// Other persistent operations
}
In the above example, we first created a physical manager factory and used the factory to create a physical manager.Then, we started a transaction and persisted.Finally, we submit a transaction or roll back the transaction when an abnormality occurs, and close the physical manager.
By using the persistent API framework, developers can easily achieve the persistent operation of data, while reducing direct interaction with the underlying database.This can improve development efficiency and reduce the complexity of the code.
in conclusion:
Specific is an indispensable part in the development of modern applications.By using the persistent API framework (such as JPA), developers can focus on the implementation of business logic without having to consider the details of the database implementation.It is believed that with the continuous development of the persistent API framework, more convenience and functions will be available for developers.
