In Spring Boot development, we often hear concepts such as PO, VO, DAO, BO, DTO, POJO and so on. These terms look similar, but they have different meanings and uses. In this article, we will introduce these concepts in detail and explain their role and usage in Spring Boot development.
PO（Persistent Object）
PO is an abbreviation for persistent object, which is a Java class that represents persistent data. In a Spring Boot application, PO is usually used to represent the table structure in the database, and each PO corresponds to a database table, which contains information such as the properties and methods of the table.
For example, we can define a UserPO class to represent the users table:
public class UserPO {
private Long id;
private String username;
private String password;
// getters and setters...
}
VO（View Object）
VO is the abbreviation of View Object, which is a Java class that represents the displayed data. In a Spring Boot application, VO is usually used to encapsulate the data required for interface display, decoupling the interface from the backend service.
For example, we can define a UserVO class to represent the display data of user information:
public class UserVO {
private String username;
private Integer age;
// getters and setters...
}
DAO（Data Access Object）
DAO is the abbreviation of Data Access Object, which is a Java class that abstracts the data access layer. In Spring Boot applications, DAOs are often used to encapsulate data access logic for use in business logic.
For example, we can define a UserDAO interface to encapsulate user data addition, deletion, modification and query operations:
public interface UserDAO {
UserPO getById(Long id);
void save(UserPO userPO);
void update(UserPO userPO);
void deleteById(Long id);
}
BO（Business Object）
BO is the abbreviation of Business Object, which is a Java class that represents business. In Spring Boot applications, BO is usually used to encapsulate business logic, decoupling business logic from other modules.
For example, we can define a UserService class to encapsulate user business logic:
@Service
public class UserService {
@Autowired
private UserDAO userDAO;
public UserDTO getUserById(Long id) {
UserPO userPO = userDAO.getById(id);
UserDTO userDTO = convertPOToDTO(userPO);
return userDTO;
}
public void addUser(UserDTO userDTO) {
UserPO userPO = convertDTOToPO(userDTO);
userDAO.save(userPO);
}
// other business methods...
}
DTO（Data Transfer Object）
DTO is the abbreviation of Data Transfer Object, which is a Java class representing data transfer. In Spring Boot applications, DTO is usually used to encapsulate data transfer logic, mainly for data transfer between different modules.
For example, we can define a UserDTO class to encapsulate the transmission information of user data:
public class UserDTO {
private String username;
private Integer age;
// getters and setters...
}
POJO（Plain Old Java Object）
POJO is the abbreviation of pure Java object, which is a kind of common Java class. In Spring Boot applications, POJOs are usually used to represent business domain entities, request parameters and response results, etc.
For example, we can define a Book class to represent book information:
public class Book {
private Long id;
private String name;
private String author;
private String isbn;
// getters and setters...
}
Summarize
In Spring Boot development, concepts such as PO, VO, DAO, BO, DTO, and POJO are very important. They each have different meanings and uses, which can help us better organize code, separate concerns, and improve code maintainability and accessibility.