了解Java Web应用程序（Struts）的结构

Question

我无法理解struts框架的布局。我有一个迷你巴士预订网络应用程序的源代码，但看不到不同文件夹中的文件如何相互配合。对于正在进行的活动的可靠解释将不胜感激。具体来说，服务文件如何与存储库文件进行交互。

考虑以下文件（我排除了某些文件的导入） com / project / data / Booking.java

public class Booking {
private int booking_id;
private int user_id;
private int trip_id;
private int payment_id;
private int seat_id;

 public Booking(){
 }

 public Booking(int user_id, int trip_id, int payment_id, int seat_id){
    this.user_id = user_id;
    this.trip_id = trip_id;
    this.payment_id = payment_id;
    this.seat_id = seat_id;
 }

public int getBooking_id() {
    return booking_id;
}

public void setBooking_id(int booking_id) {
    this.booking_id = booking_id;
}

public int getUser_id() {
    return user_id;
}

public void setUser_id(int user_id) {
    this.user_id = user_id;
}

public int getTrip_id() {
    return trip_id;
}

public void setTrip_id(int trip_id) {
    this.trip_id = trip_id;
}

public int getPayment_id() {
    return payment_id;
}

public void setPayment_id(int payment_id) {
    this.payment_id = payment_id;
}

public int getSeat_id() {
    return seat_id;
}

public void setSeat_id(int seat_id) {
    this.seat_id = seat_id;
}

}

com / project / repository / Booking.java

public class BookingRepository implements BookingRepositoryInt<Booking> {

public Booking schedule_booking(Booking obj) {
        if (obj != null && (find(obj) == null)) {
            return add(obj);
        }
        return null;
    }

    @Override
    public Booking cancel_booking(Booking obj) {
        if (obj != null && (find(obj) == null)) {
            remove(obj);
        }
        return null;
    }
 private Booking add(Booking booking){
    Connection conn = null;
    try {
        conn = getConnection();
        PreparedStatement stmt = conn.prepareStatement(INSERT_BOOKING);
        stmt.setInt(1, booking.getUser_id());
        stmt.setInt(2, booking.getTrip_id());
        stmt.setInt(3, booking.getPayment_id());
        stmt.setInt(4, booking.getSeat_id());
        stmt.execute();
        closeStatement(stmt);
        return booking;
    }
    catch (SQLException ex) {
        if (ex.getMessage().contains("Duplicate")) {
            System.out.println("Item with duplicate id already exists in repository");
            throw new DuplicateItemException("Item with duplicate id already exists in repository");
        }
        else {
            ex.printStackTrace();
            System.out.println("Failed to add item to repository");
            throw new RepositoryException(ex);
        }
    }
    finally {
        closeConnection(conn);
    }
    }

    private Booking find(Booking booking){
    Connection conn = null;
    try {
        conn = getConnection();
        PreparedStatement stmt = conn.prepareStatement(FIND_BOOKING);
        stmt.setInt(1, booking.getUser_id());
        stmt.setInt(2, booking.getSeat_id());
        ResultSet resultSet = stmt.executeQuery();
        Booking result = marshall(resultSet);
        closeStatement(stmt);
        return result;
    }
    catch (SQLException ex) {
        ex.printStackTrace();
        System.out.println("Failed to add item to repository");
        throw new RepositoryException(ex);
    }
    finally {
        closeConnection(conn);
    }
}

    private Booking remove(Booking booking){
        Connection conn = null;
    try {
        conn = getConnection();
        PreparedStatement stmt = conn.prepareStatement(DELETE_BOOKING);
        stmt.setInt(1, booking.getUser_id());
        stmt.setInt(2, booking.getSeat_id());
        stmt.execute();
        closeStatement(stmt);
        return booking;
    }
    catch (SQLException ex) {
        ex.printStackTrace();
        System.out.println("Failed to fetch item from repository");
        throw new RepositoryException(ex);
    }
    finally {
        closeConnection(conn);
    }
}


    private Booking marshall(ResultSet result) throws RepositoryException, SQLException{
    if (result == null) {
        return null;
    }
    Booking booking = null;
    if (result.next()) {
        int booking_id = result.getInt(BOOKING_ID);
        int user_id = result.getInt(USER_ID);
        int trip_id = result.getInt(TRIP_ID);
        int payment_id = result.getInt(PAYMENT_ID);
        int seat_id = result.getInt(SEAT_ID);
        booking = new Booking(user_id, trip_id, payment_id, seat_id);
        booking.setBooking_id(booking_id);
    }
    return booking;
}

private Connection getConnection(){
    return MySQLHelper.getConnection();
}



private static void closeStatement(Statement stmt){
    if (stmt != null) {
        try {
            stmt.close();
            //stmt = null;
        }
        catch (SQLException ex) {
            ex.printStackTrace();
        }
    }
} 

com / project / repository / BookingRepositoryInt.java

 public interface BookingRepositoryInt<User> {

    public User schedule_booking (User obj);
    public User cancel_booking (User obj);

}

com / project / service / BookingManagerInt.java

import com.project.data.Booking;

public interface BookingManagerInt {
    public static final String BOOKING_MANAGER = "BookingManager";
    public static final String BOOKING = "booking";

    public Booking schedule_booking (Booking booking);
    public Booking cancel_booking (Booking booking);

}

com / project / service / BookingManager.java

import com.project.data.Booking;
import com.project.repository.BookingRepository;
import com.project.repository.BookingRepositoryInt;

public class BookingManager implements BookingManagerInt {

        public Booking schedule_booking(Booking booking) {
            // correct the code segment below
            BookingRepositoryInt rep = new BookingRepository();
            return (Booking) rep.schedule_booking(booking);
        }

        public Booking cancel_booking(Booking booking) {
            // correct the code segment below
            BookingRepositoryInt rep = new BookingRepository();
            return (Booking) rep.cancel_booking(booking);
        }

    }