Introduction to the technical principle of UJO ORM framework in the Java library
Introduction to the technical principle of UJO ORM framework in the Java library
UJO (Unify Java Object) is a process of Ava -based ORM (object relationship mapping) framework, which is used to simplify the process of database operation and data persistence.It provides a simple and powerful way to map the tables in the Java object with the tables in the relational database to achieve data storage and retrieval.
The technical principles of the UJO ORM framework are as follows:
1. Note drive: UJO ORM uses annotations to define the mapping relationship with the database table.Developers can use annotations in the Java class to identify the corresponding relationship between this class and database tables, including table names, columns, primary keys, etc.In this way, Ujo ORM will generate the corresponding SQL statement according to the definition of the annotation, thereby realizing database operations.
2. Reflective mechanism: UJO ORM uses Java's reflection mechanism to analyze and operate the Java object, so that developers do not need to manually write tedious SQL statements.Through reflection, Ujo ORM can create and access the attributes of the objects dynamically, read and write the field value of the object, thereby realizing the conversion between database records and Java objects.
3. Database connection pool: In order to improve the performance and efficiency of database operations, UJO ORM uses a database connection pool to manage and reuse database connections.The connection pool can create a certain number of database connections and manage it in advance. When a new database operation request, you can directly obtain the connection from the connection pool to avoid frequent creation and closing the database connection, thereby increasing the system's response speed and speed and speed and speed and speed of the system.Volver.
The following is a simple Java code example. It demonstrates how to use the UJO ORM framework for database operations:
import org.ujorm.orm.metaModel.MetaParams;
import org.ujorm.orm.Session;
import org.ujorm.orm.OrmHandler;
import org.ujorm.orm.Query;
import org.ujorm.orm.ao.CachePolicy;
import org.ujorm.orm.annot.OrmTable;
@OrmTable("user")
public class User {
private Integer id;
private String name;
private String email;
// omit the creation function and getter/setter method
public static void main(String[] args) {
OrmHandler handler = new OrmHandler();
// Configure database connection
MetaParams params = new MetaParams("jdbc:mysql://localhost:3306/mydb", "root", "password");
handler.config(params);
// Create a database meeting
Session session = handler.createSession();
session.setCachePolicy(CachePolicy.DEFAULT);
// Insert a new user
User user = new User();
user.setName ("Zhang San");
user.setEmail("zhangsan@example.com");
session.save(user);
// Query the user
Query<User> query = session.createQuery(User.class);
query.where(session.getDatabase().getTable(User.class).getColumnByName("name")).eq("张三");
User result = query.fetchOne();
System.out.println(result);
}
}
In the above example code, the mapping relationship between the identification of `` user` classes and database tables `user` is first annotated.Then, configure the database connection parameters with the `ORMHANDLER` class and the` metaparams` class, and create a database session.Then, a new `User` object was created and called the` Save` method to persist in the database.Finally, by creating query objects and calling the `fetchone` method to query user information that meets conditions.
Through the UJO ORM framework, developers can easily implement the mapping of Java objects and database tables, thereby simplifying the process of database operation and data persistence, and improving development efficiency and code readability.
