Analysis of the technical principle of Kodo framework in Java Class Library
Analysis of the technical principle of Kodo framework in Java Class Library
The Kodo framework is a Java persistence framework, which aims to simplify the interaction between applications and databases.It provides a simple interface for developers, making the database operation easier and efficient.
The technical principles of the Kodo framework mainly involve the following aspects:
1. Object-Relationship Map (ORM):
Kodo uses ORM technology to map Java objects to the table structure in the relationship database.It can automatically generate the database table for the Java class, and map the fields or attributes in the Java class to columns in the database table.
2. Specific context management:
Kodo manages the persistence of Java objects in the database by creating a persistent context.The persistent context is a similar cache container that is used to track the state changes of the object and synchronize these changes to the database.
3. Database query:
Kodo provides a powerful query function that allows developers to easily perform database query operations.It supports the use of object -oriented query language (such as JPQL) to write inquiries and converts the query results to Java objects.
4. Cache management:
The Kodo framework improves the performance of database access through cache technology.It uses cache to store frequent access to access, thereby reducing the number of access to databases and improving the performance of the application.
The core of the Kodo framework is a component called Kodo Runtime.It provides the underlying support for JDO (Java Data Objects) and JPA (Java Persistence API).When using the Kodo framework, you need to ensure the correct configuration of Kodo Runtime to make it work with applications and databases.
The following is an example of the Java code and related configuration, which shows how to use the Kodo framework for persistent operations:
1. Define the physical class:
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class Employee {
@Id
private int id;
private String name;
// Getters and setters
}
2. Configure Persistence.xml file:
<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
version="2.1">
<persistence-unit name="myPersistenceUnit" transaction-type="RESOURCE_LOCAL">
<provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider>
<class>com.example.Employee</class>
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/mydatabase"/>
<property name="javax.persistence.jdbc.user" value="root"/>
<property name="javax.persistence.jdbc.password" value="password"/>
</properties>
</persistence-unit>
</persistence>
3. Perpetual operation:
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class Main {
public static void main(String[] args) {
EntityManagerFactory emf = Persistence.createEntityManagerFactory("myPersistenceUnit");
EntityManager em = emf.createEntityManager();
// Starting transaction
em.getTransaction().begin();
// Create an Employee object and set the attribute
Employee employee = new Employee();
employee.setId(1);
employee.setName("John Doe");
// Save the object in the database
em.persist(employee);
// Submit a transaction
em.getTransaction().commit();
// Turn off the physical manager and physical manager factory
em.close();
emf.close();
}
}
The above code fragment demonstrates how to use the Kodo framework to create an Employee object and divert it into the database.By configured the Persistence.xml file, we designated the connection information of the database.+> CreateEntityManagerFactory () method Return a EntityManagerFactory instance that is responsible for creating an EntityManager instance.Then, by calling the Persist () method, we save the Employee object into the database.
In summary, the technical principles of the Kodo framework mainly include object-relationship mapping, persistent context management, database query and cache management.By using the corresponding Java class and configuration, developers can easily use the Kodo framework for the persistent operation of the Java object.
