Detailed explanation of the technical principles of the POJAVA persistent framework in the Java library

The technical principle of the POJAVA persistence framework in the Java class library Overview Pojava's persistence framework is a tool library for simplifying the persistence of the Java object. It provides a set of simple and easy -to -use APIs that allow developers to easily save the Java object into the database.This article will introduce the technical principles of the POJAVA persistence framework in detail and provide some Java code examples. Technical principle The core concept of the POJAVA persistence framework is to map the Java object to the table in the database, and to configure the mapping between classes and fields, and persist the status of the Java object into the database.The following is the key technical principle of the POJAVA persistent framework: 1. Note configuration: Pojava's durable framework uses annotations to configure the mapping relationship of classes and fields.By adding @Entity annotations to the physical class, the framework can map this class to the table in the database; by adding @Column annotations to the field, the frame can be mapped to columns in the database.The annotation configuration provides flexibility and scalability, and developers can perform flexible configurations according to actual needs. 2. Database connection: POJAVA's persistence framework interacts with the database through the JAVA's JDBC API.Developers need to provide the relevant information of the database connection in the configuration file, including the database URL, username and password.The framework uses this information to establish a connection with the database and execute the SQL statement when needed. 3. SQL generation: POJAVA's durable framework uses database metadata to obtain the field information of the physical class, and generates the corresponding SQL statement according to the annotation of the field.For example, the framework can generate the object into the database according to the annotation of the field. It can also generate records in the database of the SELECT statement according to the annotation of the field.The process of SQL is automated, and developers only need to configure the injection solution. 4. Object relationship mapping: POJAVA's persistence framework supports the relationship mapping between objects, including one -to -one, one -to -many, and multiple -to -multiple relationships.By adding annotations to related fields, the framework can automatically process the relationship between objects.For example, by adding @onetomany annotations on a pair of multi -relationships, the framework can automatically load records of associated objects. Java code example Below is a simple example of using Pojava's persistent framework: 1. Define the physical class @Entity public class User { @Id private int id; @Column private String name; // omit the constructor and getter/setter } 2. Create a database table sql CREATE TABLE user ( id INT PRIMARY KEY, name VARCHAR(50) ); 3. Save the object to the database User user = new User(1, "John"); PersistenceManager persistenceManager = PersistenceManagerFactory.createPersistenceManager(); persistenceManager.save(user); In this example, we define a physical class called User and configured with the User table in the database for mapping.Then use PersistenceManager to save the User object to the database. Summarize The Pojava persistence framework is a tool library that simplifies the persistence of the Java object. It provides a convenient and easy -to -use API to achieve the persistence of Java objects through technical principles such as annotations, database connection, SQL generation, and object relationship mapping.Developers can use the POJAVA persistence framework to simplify the development of database operations according to the actual needs.