The technical principle interpretation of the UJO ORM framework in the Java class library

The UJO ORM framework is an ORM (object relationship mapping) framework used in the Java library.This article will interpret the technical principles of the UJO ORM framework and provide some specific Java code examples. 1. Overview of the UJO ORM framework The UJO ORM framework is an open source, lightweight ORM framework, which aims to simplify data interaction between Java applications and databases.It provides a way to map the database table to the Java object, so that developers can operate the database more conveniently without writing the SQL statement directly. Second, analysis of the technical principle of UJO ORM framework 1. The physical mapping of the annotation drive The UJO ORM framework uses annotations to identify the mapping relationship between the Java class and the database table.By using @Entity annotations on the Java class, developers can specify the name of the corresponding database table of this class.You can use the @Column annotation to specify the attribute of the corresponding database field field on the class member variables.In this way, the UJO ORM framework can automatically associate the Java object with the database table. Below is a simple example that demonstrates how to use the UJO ORM framework for physical mapping: @Entity(table = "users") public class User { @Column(name = "id", primaryKey = true) private int id; @Column(name = "username") private String username; // omit the getter and setter method } In the above examples, the User class is annotated as an entity and maximizes the "USERS" table in the database.The ID and username fields correspond to the "ID" and "username" columns of the database table, respectively. 2. Database query and operation The UJO ORM framework provides a series of methods to perform database queries and operations.Developers can use the SQLBuilder class to build SQL query statements and perform query by calling the corresponding method.In addition, the UJO ORM framework also provides some commonly used CRUD (creation, reading, updating, deleting) operations, such as Save, Find, Update, and Delete. The following is a simple example that shows how to use the UJO ORM framework for database operation: // Query the user List<User> users = SQLBuilder.select(User.class) .where("username = ?", "admin") .findAll(); // Insert a new user User newUser = new User(); newUser.setUsername("test"); SQLBuilder.insert(newUser).execute(); // Update users SQLBuilder.update(User.class) .set("username", "new_username") .where("id = ?", 1) .execute(); // delete users SQLBuilder.delete(User.class) .where("id = ?", 1) .execute(); In the above examples, first use SQLBUILDER for query, and then demonstrate the operation of insertion, update and deletion. 3. Affairs support The UJO ORM framework also provides transaction support, enabling developers to maintain data consistency during the database operation.You can use the UJOTRANSACTION class to start, submit or return transactions. The following is a simple example, showing how to use the UJO ORM framework for transaction control: try (UjoTransaction tx = new UjoTransaction()) { // Insert a new user User newUser = new User(); newUser.setUsername("test"); SQLBuilder.insert(newUser).execute(); // Update users SQLBuilder.update(User.class) .set("username", "new_username") .where("id = ?", 1) .execute(); tx.commit (); // Submit transactions } catch (Exception e) { // Treatment abnormalities, roll back transactions tx.rollback(); } In the above examples, use Ujotransaction to start transactions, and then perform database operations in transactions.Finally, the transaction is submitted through the Commit () method or rolled back through the Rollback () method. 3. Summary The UJO ORM framework is a simple and easy -to -use ORM framework. It can achieve physical mapping through annotations, provides convenient database operation methods, and supports transaction control.By using the UJO ORM framework, developers can efficiently handle data interaction with the database and improve development efficiency.