Explore the technical principles of the POJAVA persistent framework in the Java class library

The Pojava persistence framework is a data persistence technology used in the Java library, which aims to simplify the data storage and access process of data in Java applications.It provides a set of rich features that can easily connect databases, execute SQL query, and create object mapping. The technical principles of Pojava's persistent framework mainly include the following aspects: 1. Database connection: POJAVA persistent framework uses JDBC (Java database connection) technology to connect the database.It provides a database connection pool that initializes the database connection when the application starts to avoid frequent opening and turning the database connection. // Use POJAVA's persistent framework to create database connections Connection connection = POJavaPersistence.getConnection(); 2. SQL statement execution: POJAVA's persistence framework allows developers to use simple APIs to perform SQL query and update operations.It provides a series of methods that can easily build and execute SQL statements and processes the results.For example, you can use the QueryBuilder class provided by the framework to build a complex select statement. // Use the POJAVA persistent framework to execute SQL query String sql = "SELECT * FROM customers WHERE age > ? AND city = ?"; QueryBuilder queryBuilder = new QueryBuilder(sql); queryBuilder.addparameter (18); // Set age parameters queryBuilder.addparameter ("Beijing"); // Set urban parameters ResultSet resultSet = POJavaPersistence.executeQuery(queryBuilder); 3. Object mapping: Pojava's persistence framework provides a simple method for mapping between objects and database tables.It uses annotations or xml configuration files to define the mapping relationship between objects and tables.Developers can use@ENTITY,@Table,@Column, etc. as Java classes and member variables to add mapping configuration. // Use the POJAVA persistence framework to define the mapping relationship between objects and tables @Entity @Table(name = "customers") public class Customer { @Column(name = "id") private int id; @Column(name = "name") private String name; // getter and setter method } 4. Affairs management: POJAVA's persistent framework provides simple transaction management functions.Developers can use the Transaction class provided by the framework to start, submit and roll back.All SQL statements executed in one transaction will be processed when submitting or rolling to ensure the consistency of the data. // Use POJAVA's persistent framework for transaction management Transaction transaction = new Transaction(); transaction.begin(); try { // Execute a series of database operations transaction.commit(); } catch (Exception e) { transaction.rollback(); } In short, the POJAVA persistence framework uses some key technical principles in the Java class library, such as the JDBC database connection, the execution of SQL statements, object mapping, and transaction management.By using the POJAVA persistence framework, developers can more conveniently perform data persistence operations, thereby improving the development efficiency and stability of the application.