DTO(Data Transfer Object) ? DAO(Data Access Object)? ????? ??, ?? Java ?? ???????? ?? ???? ?? ??? ?????. ??? ??? ?? ??? ??????.

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DTO(??? ?? ??):

??: DTO? ??????? ??? ?? ???? ?? ???? ????? ??? ??? ?????.

?? ??: ??? ?? ?? ?????(?? ???? ?????) ???? ???? ??? ? ?? ???? ??? ?? ???? ???? ????? ? ?? ?????.

??:

???? ???? ??? ???? ????.

getter? setter? ????? ???? ??? ???? ????.

???? ???? API ??? ?? ???? ? ????.

DTO? ?:

?? ??? UserDTO {
?? ??? ??? ??;
?? ??? ???;

// Constructor
public UserDTO(String username, String email) {
    this.username = username;
    this.email = email;
}

// Getters and setters
public String getUsername() {
    return username;
}

public void setUsername(String username) {
    this.username = username;
}

public String getEmail() {
    return email;
}

public void setEmail(String email) {
    this.email = email;
}

}

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DAO(??? ??? ??):

??: DAO? ???????? ????? ?????. ??? ??? ????? ??? ??? ?? CRUD(??, ??, ????, ??) ??? ???? ??? ?????.

?? ??: ?? ?? ??? ???? ?????? ??? ???? ??? ?????.

??:

SQL ?? ?? ORM(?: Hibernate, JPA) ??? ??????.

?????? ???? ?????.

save(), findById(), delete() ?? ?? ??? ??? ???? ?????.

DAO? ?:

java.sql.Connection ????;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

?? ??? UserDAO {
?? ?? ??;

public UserDAO(Connection connection) {
    this.connection = connection;
}

public UserDTO getUserById(int id) throws Exception {
    String query = "SELECT username, email FROM users WHERE id = ?";
    PreparedStatement statement = connection.prepareStatement(query);
    statement.setInt(1, id);
    ResultSet resultSet = statement.executeQuery();

    if (resultSet.next()) {
        String username = resultSet.getString("username");
        String email = resultSet.getString("email");
        return new UserDTO(username, email);
    }
    return null;
}

public void saveUser(UserDTO user) throws Exception {
    String query = "INSERT INTO users (username, email) VALUES (?, ?)";
    PreparedStatement statement = connection.prepareStatement(query);
    statement.setString(1, user.getUsername());
    statement.setString(2, user.getEmail());
    statement.executeUpdate();
}

}

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??:

???????? DAO? ???????? ???? ???? DTO ??? ???? ?? ?? ??(?: ??? ?? ????)?? ????.

?? ??:

1. ???? ??: ??? ??? ?????.

2. ??? ??: DAO? ?? ???? ???? ????? ?????.

3. DAO ???: ???? ???? DTO? ???? ?????.

?? ?:

//????
?? UserDTO getUserDetails(int id) {
return userService.getUserById(id);
}

//???
?? UserDTO getUserById(int id) {
return userDAO.getUserById(id);
}

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??:

DTO: ??? ??? ????? ?? ????? UI ?? ?? API ??? ?????.

DAO: ?????? ??? ??? ?? ????? ??? ? ???? ???? ????.

? ??? ???? ??? ???? ?????!

? ??? ????? ??? DTO ? DAO? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!