Analysis of the technical principles of the POJAVA persistence framework in the Java class library

Analysis of the technical principles of the POJAVA persistence framework in the Java class library Pojava is a persistent framework based on the Java language, which is used to simplify the process of continuousizing the Java object into the database.It provides a simple and efficient way that allows developers to easily store objects into the database and can easily retrieve and update operations. Pojava's technical principles are mainly based on two key concepts of reflection and annotations.It uses Java's reflection mechanism to dynamically access and operate the attributes of the object, thereby achieving the persistence of the object.The annotation is used to configure and mark the metadata of the object. First of all, in Pojava, developers need to add annotations to a persistent Java class.These annotations include@Entity,@Column,@ID, etc.@ENTITY annotation is used to mark a Java class as a persistent entity, and @Column annotations are used to mark a column in a attribute corresponding to the database. Next, when performing persistent operations through POJAVA, we first need to create a Pojava session object.Then, the method of session objects can be used to perform various database operations, such as adding (insert), query (select), update, and delete (delete). Specifically, when the Java object is stored to the database, the corresponding database table will be created based on the object's annotation information.When a Java object needs to be inserted into the database, POJAVA will dynamically generate the corresponding SQL statement according to the object's annotation information, and insert the attribute value of the object into the corresponding database table. When the data needs to be retrieved from the database, POJAVA will generate the corresponding SQL statement according to the query conditions, and encapsulate the query result as a Java object.Developers can use query methods provided by POJAVA, such as querying according to the primary key, query according to conditions, etc. When updating and deleting data, POJAVA will also generate the corresponding SQL statement according to the annotation information of the object, and apply the updated or deleted operation to the database. Below is a simple example code that shows how to use Pojava for the object persistence: @Entity public class User { @Id @Column(name = "id") private int id; @Column(name = "name") private String name; @Column(name = "age") private int age; // omit the creation function and getter/setter method // Other business logic } public class Main { public static void main(String[] args) { Session session = new Session("jdbc:mysql://localhost:3306/mydb", "username", "password"); User user = new User(1, "John", 25); // Insert data session.insert(user); // Query data User retrievedUser = session.select(User.class, 1); System.out.println(retrievedUser.getName()); // update data retrievedUser.setAge(26); session.update(retrievedUser); // delete data session.delete(User.class, 1); } } In the above example, we define a User class and add corresponding annotations, and then insert, query, update, and delete through the Session object. In short, the POJAVA persistence framework realizes the function of the persistence of the Java object to the database, and simplifies the work of developers through reflection and annotations.It provides a simple and easy -to -use way to access and operate the database, so that developers can focus more on the realization of business logic.