The technical principles of the UJO ORM framework in the Java library
The technical principles of UJO ORM framework in the Java library
Summary:
UJO ORM is a lightweight -oriented object mapping (ORM) framework (ORM) used in the Java library.This article focuses on the technical principles of the UJO ORM framework.First, we will introduce the concepts and functions of ORM, and then discuss the design ideas, core principles and key features of the UJO ORM framework in detail.Finally, we combine the Java code example to enable readers to better understand the UJO ORM framework.
1. ORM concept and role
ORM (Object-Relational Mapping) is a technology that mappore between the object model and the relationship database.The ORM framework allows developers to operate the database through object -oriented methods, thereby simplifying the durable encoding work.ORM can automatically map the tables in the Java class and the relationship database, and maxide the attributes of the object with the field of the database table, and realize the operation of data reading, preservation and update.
2. Design ideas of UJO ORM framework
The design goal of the UJO ORM framework is to provide a simple and easy -to -use ORM solution.UJO ORM uses annotations to perform mapping configurations, and realizes the mapping relationship between classes and tables, fields and attributes by using custom annotation markers, fields, and methods.UJO ORM also supports high -level features such as dynamic generation SQL and delay loading.
3. The core principle of the UJO ORM framework
The core principle of the UJO ORM framework is to implement the mapping between the object and the database through the reflection mechanism.It uses Java's reflection capabilities to obtain various metadata information of the Java class, such as category names, field names, annotations, etc.Through these metadata information, Ujo ORM can dynamically generate SQL statements, create and update the database table according to the definition of the class, and operate the attribute values of the object with the field of the database table.
4. The key features of the UJO ORM framework
(1) Map configuration: The UJO ORM framework uses annotations for mapping configuration. Through information such as the method of marking the physical class, attributes, and relationships, the configuration work of the developer is simplified.
(2) Object -oriented query: The UJO ORM framework provides object -oriented query grammar. Developers can inquire through the Java code without writing complex SQL statements.
(3) Transaction Management: UJO ORM Framework supports transaction management mechanism. Developers can achieve atomicity and consistency management of database operations through the boundaries of the bid marking transaction.
(4) Cross -database platform support: The UJO ORM framework provides support for a variety of relationship database systems. Developers can easily switch different database platforms.
5. Java code example of the UJO ORM framework
Below is a simple Java code example, demonstrating how to use the UJO ORM framework for data persistence operation:
// Relevant classes to import UJO ORM framework
import org.ujorm.orm.*;
import org.ujorm.orm.ao.*;
import org.ujorm.orm.metaModel.*;
import org.ujorm.orm.template.*;
// Define a physical class
public class UserEntity extends OrmTable<UserEntity> {
@Column(pk = true)
private Long id;
@Column(index = "idx_name")
private String name;
// omit the getter and setter method
// Create an ORMHANDLER object
private static final OrmHandler handler = new OrmHandler();
// Create a database meeting
private static final OrmUjo session = new OrmUjo();
// Save the user
public void save() {
try {
session.save(this);
} catch (Exception e) {
e.printStackTrace();
}
}
// Query the user
public static UserEntity findById(Long id) {
return handler.load(UserEntity.class, id);
}
}
// Main application
public class Main {
public static void main(String[] args) {
// Create a user entity object
UserEntity user = new UserEntity();
user.setName("John");
// Save the user to the database
user.save();
// Query the user according to the ID
UserEntity user2 = UserEntity.findById(1);
System.out.println(user2.getName());
}
}
This article introduces the technical principle of the UJO ORM framework.By using the UJO ORM framework, developers can simplify the durable work and improve development efficiency.It is hoped that this article can help readers understand and use the UJO ORM framework.
