Java -class library MapperDao framework technical principles and use methods introduced

Introduction to the technical principles and usage methods of Java class library MapperDao framework Mapperdao is an ORM (object relationship mapping) framework used in the Java library, which aims to simplify the interaction between Java applications and relational databases.This article will introduce the technical principles of the MapperDao framework and how to use the framework to improve development efficiency. 1. MapperDao framework technical principle 1. Database mapping Mapperdao provides a database mapping function to realize the conversion between objects and relational databases.Developers can indicate how Mapperdao is instructed by the mapping relationship between Entity and tables to store data into databases.This mapping relationship can be defined by annotating or configuration files. 2. Query language Mapperdao provides a flexible and easy -to -use query language, allowing developers to easily perform database query operations.Developers can use the query language definition query conditions, sorting rules, and return results.This query language is based on the Java code, which can provide compilation inspection and type security. 3. Affairs management The Mapperdao framework also provides transaction management functions to ensure that multiple database operations are executed in one transaction.This can ensure that all operations will be rolled back when abnormal conditions, so as to maintain the consistency of the database. 2. Use MapperDao framework The following is a simple sample code using the MapperDao framework to demonstrate how to perform the mapping and database operation of the physical class: 1. Add MapperDao dependence First, the dependencies of the MapperDao framework need to be added to the construction file of the project.If you use Maven for project management, you only need to add corresponding dependencies to the pom.xml file. 2. Define the physical class Create a physical class to represent the table in the database.You can use the annotation or configuration file to indicate how Mapperdao is mapped to the database table. @Entity ("Users") // Specify a table mapped to "Users" public class User { @Id // Specify as the main key field private int id; private String name; private int age; // getters and setters } 3. Initialize MapperDao At the entrance of the application, initialize the MapperDao and configure the database connection information. DataSource DataSource = ... // Create a data source SessionFactory sessionFactory = new SessionFactoryBuilder().withDataSource(dataSource).build(); MapperDao mapperDao = sessionFactory.getMapperDao(); 4. Database operation Use MapperDao for database operation: -Stch -in data: User user = new User(); user.setId(1); user.setName("John"); user.setAge(25); mapperDao.insert(user); - Query data: List<User> users = mapperDao.query(User.class).where("age > :age").with("age", 20).list(); - update data: user.setAge(30); mapperDao.update(user); - delete data: mapperDao.delete(user); 5. Affairs management You can use the transaction management function provided by Mapperdao to ensure that multiple database operations are executed in one transaction.You can use the `@transactional` annotation on the code block that requires transaction management. @Transactional public void saveUser(User user) { mapperDao.insert(user); // other database operations } This article introduces the technical principles and usage methods of the Java class library Mapperdao framework.By using the MapperDao framework, developers can easier database operations and improve the readability and maintenance of code.It is hoped that readers can learn how to use the Mapperdao framework to improve the development efficiency of Java applications.