UJO ORM framework interpretation of technical principles in the Java library

UJO ORM framework interpretation of technical principles in the Java library Abstract: Ujo ORM (object relationship mapping) is a Java -based ORM framework that is used to map the object model to the table structure in the relationship database.This article will introduce the technical principles of the UJO ORM framework in the Java class library, and demonstrate its usage through the Java code example. Introduction to UJO ORM framework UJO ORM is an open source Java class library that provides a way to simplify the persistence of objects.It uses object -oriented ideas and the characteristics of Java language, and establish a mapping relationship between the Java object and the database table, so that developers can use the object operationEssence 2. Technical principles of the UJO ORM framework The technical principles of the UJO ORM framework mainly include object-relationship mapping, transaction management and query language. 1. Object-Relationship mapping (ORM) The UJO ORM framework defines the mapping relationship between the Java object and the database table by annotating or XML configuration files.Developers can use the annotation method of the mapping relationship between the bidding fields and tables in the Java class, or the XML configuration file can be used for mapping definition.Through the ORM mechanism, the UJO ORM framework can automatically create database tables, insert data, update data and other operations. For example, assuming we have a Java user, it reflects a user watch User of the database: public class User { @Id private int id; private String name; private int age; // omit the getter and setter method } In the above example, the @id annotation indicates that the ID field is the primary key, and the UJO ORM framework will correspond to the ID field with the main key of the database table. 2. Affairs management The UJO ORM framework provides a transaction management mechanism to ensure the consistency of multiple database operations.You can use annotations or programming methods to define transactions.If the transaction annotation is marked on the method, the UJO ORM framework will create a transaction for this method to ensure that the database operation in the method is either successful or all fails. For example, use @Transaction annotation to mark a method with database operations: @Transactional public void saveUser(User user) { // Insert user data // Update other related data } In the above examples, using @TransActional annotation indicates that the method needs to be managed by transaction. If there is any failure in the database operation in the method, all operations will be rolled back. 3. Query language The UJO ORM framework provides a flexible and powerful query language to perform the database query operation, similar to the SQL statement.Developers can use object -oriented syntax to write query conditions to avoid directly writing complex SQL statements. For example, the query language of the UJO ORM framework is used to query users who are older than or equal to 18 years old in the user table: List<User> users = session.createQuery(User.class) .where("age >= ?", 18) .list(); 3. Summary The UJO ORM framework is a simplified ORM framework that simplifies objects. It realizes the mapping relationships, transaction consistency and flexible queries of databases through technical principles such as object-relationship mapping, transaction management and query language.Developers can improve development efficiency and reduce programming complexity by using the UJO ORM framework.