The technical principles and practice of the UJO ORM framework in the Java library

The technical principles of UJO ORM framework in the Java library analysis and practice Overview: The UJO ORM (object relationship mapping) framework is an open source Java class library, which aims to simplify the data persistence operation between the Java application and the relationship database.This article will analyze the technical principles of the UJO ORM framework and provide actual Java code examples. 1 Introduction The ORM framework aims to solve the mapping problem between the Java object and the relationship database.By using the ORM framework, developers can use object -oriented language (such as Java) to operate the database without writing complex SQL statements.The UJO ORM framework is a lightweight, flexible and easy -to -use framework. It provides a simple way to realize the mapping between objects to relational databases. 2. Technical principles The UJO ORM framework is based on the following technical principles to achieve access and operation of the relationship database: a. Annotations: Ujo ORM uses annotations to define the mapping relationship between the Java class and the database table.By using the @Ujoentity annotation on the Java class, this class is associated with the table in the database.Through the @UJOPROPERTY annotation, the attributes of the Java class can be mapped to the column of the database table.UJO ORM also supports other annotations, such as @UjoprimaryKey to define the main key attributes,@ujoINDEX is used to define indexes. b. Database Connection: The UJO ORM framework uses the JDBC (Java database connection) technology to establish a connection with the relationship database.Developers need to provide information such as the connection of the database, username and password, so that the UJO ORM framework can communicate with the database. c. Data Query and Manipulation: The UJO ORM framework provides a series of APIs to perform database query and operations.Through the UjoQuery class, you can build a complex query statement, and use methods such as Findall, Updateall, and Deleteall to perform query, update and delete operations.UJO ORM also supports transaction processing to ensure the consistency and integrity of the data. d. Data Type Mapping: The UJO ORM framework mappies the type of the Java class with the columns of the database table.For example, the String type of Java can be mapped as the Varchar column of the database. The Integer type of the Java can be mapped into the INT column of the database.UJO ORM realizes data conversion between Java objects and databases through data type mapping. 3. Practice example The following is a simple example of a simple UJO ORM framework: @UjoEntity(table="users") public class User { @UjoProperty(column="id") @UjoPrimaryKey private int id; @UjoProperty(column="name") private String name; @UjoProperty(column="age") private int age; // omit the getter and setter method } public class Main { public static void main(String[] args) { // Create a database connection UjoManager.getInstance().connect("jdbc:mysql://localhost/test", "username", "password"); // Create a user object User user = new User(); user.setId(1); user.setName("John Doe"); user.setAge(25); // Insert user records UjoEntityManager.getInstance().insert(user); // Query user record UjoQuery query = new UjoQuery(User.class); query.addCondition(UjoCondition.equals("name", "John Doe")); List<User> users = UjoEntityManager.getInstance().findAll(query); // Update user records User userToUpdate = users.get(0); userToUpdate.setAge(30); UjoEntityManager.getInstance().update(userToUpdate); // Delete user records UjoEntityManager.getInstance().delete(userToUpdate); } } The above example demonstrates how to use the UJO ORM framework to perform the persistent operation of the object in the Java library.First, the mapping relationship between the User class and the database table is defined through the @UJONTITY and @Ujoproperty annotations.Then build a connection with the database through the UJOMANAGER class.Next, create a User object and insert it into the database using the INSERT method of the UjoentityManager class.Build query conditions through the UjoQuery class and use the Findall method of the UjoentityManager class to query the database records.Finally, the UPDATE and Delete methods of the UjontityManager class are updated and deleted database records. By learning the technical principles and practical examples of the UJO ORM framework, developers can more efficiently perform data persistent operations between Java applications and relational databases.The flexibility and ease of use of the UJO ORM framework make it one of the preferred framework for developers.