设计一个在线教育知识付费源码系统(面向对象设计)。
解决方案:假设我们想要设计一个基本的内容付费阅读系统并带小程序，提供以下功能：
•查找知识数据库并阅读付费内容；
•用户成员的创建和扩展；
•基于用户分级权限管理，并且这个用户只能获权后阅读。
完整源码：zs.xcxyms.top
类OnlineReaderSystem代表程序的主体。我们可以实现这个类，让它存储有关所有涉及用户管理的权限分级的信息，并刷新显示，但这会使这个类变得相当庞大。相反，我们选择将这些组件拆分成Library、UserManager和Display类。
类:
1、用户
2、知识
3、UserManager
4、OnlineReaderSystem
代码如下:
import java.util.HashMap;
/*
* This class represents the system
*/
class OnlineReaderSystem {
private Library library;
private UserManager userManager;
private Display display;
private Book activeBook;
private User activeUser;
public OnlineReaderSystem()
{
userManager = new UserManager();
library = new Library();
display = new Display();
}
public Library getLibrary()
{
return library;
}
public UserManager getUserManager()
{
return userManager;
}
public Display getDisplay()
{
return display;
}
public Book getActiveBook()
{
return activeBook;
}
public void setActiveBook(Book book)
{
activeBook = book;
display.displayBook(book);
}
public User getActiveUser()
{
return activeUser;
}
public void setActiveUser(User user)
{
activeUser = user;
display.displayUser(user);
}
}
/*
* We then implement separate classes to handle the user
* manager, the library, and the display components
*/
/*
* This class represents the Library which is responsible
* for storing and searching the books.
*/
class Library {
private HashMap<Integer, Book> books;
public Library()
{
books = new HashMap<Integer, Book>();
}
public Boolean addBook(int id, String details, String title)
{
if (books.containsKey(id)) {
return false;
}
Book book = new Book(id, details, title);
books.put(id, book);
return true;
}
public Boolean addBook(Book book)
{
if (books.containsKey(book.getId())) {
return false;
}
books.put(book.getId(), book);
return true;
}
public boolean remove(Book b)
{
return remove(b.getId());
}
public boolean remove(int id)
{
if (!books.containsKey(id)) {
return false;
}
books.remove(id);
return true;
}
public Book find(int id)
{
return books.get(id);
}
}
/*
* This class represents the UserManager which is responsible
* for managing the users, their membership etc.
*/
class UserManager {
private HashMap<Integer, User> users;
public UserManager()
{
users = new HashMap<Integer, User>();
}
public Boolean addUser(int id, String details, String name)
{
if (users.containsKey(id)) {
return false;
}
User user = new User(id, details, name);
users.put(id, user);
return true;
}
public Boolean addUser(User user)
{
if (users.containsKey(user.getId())) {
return false;
}
users.put(user.getId(), user);
return true;
}
public boolean remove(User u)
{
return remove(u.getId());
}
public boolean remove(int id)
{
if (users.containsKey(id)) {
return false;
}
users.remove(id);
return true;
}
public User find(int id)
{
return users.get(id);
}
}
/*
* This class represents the Display, which is responsible
* for displaying the book, it's pages and contents. It also
* shows the current user. * It provides the method
* turnPageForward, turnPageBackward, refreshPage etc.
*/
class Display {
private Book activeBook;
private User activeUser;
private int pageNumber = 0;
public void displayUser(User user)
{
activeUser = user;
refreshUsername();
}
public void displayBook(Book book)
{
pageNumber = 0;
activeBook = book;
refreshTitle();
refreshDetails();
refreshPage();
}
public void turnPageForward()
{
pageNumber++;
System.out.println("Turning forward to page no " +
pageNumber + " of book having title " +
activeBook.getTitle());
refreshPage();
}
public void turnPageBackward()
{
pageNumber--;
System.out.println("Turning backward to page no " +
pageNumber + " of book having title " +
activeBook.getTitle());
refreshPage();
}
public void refreshUsername()
{
/* updates username display */
System.out.println("User name " + activeUser.getName() +
" is refreshed");
}
public void refreshTitle()
{
/* updates title display */
System.out.println("Title of the book " +
activeBook.getTitle() + " refreshed");
}
public void refreshDetails()
{
/* updates details display */
System.out.println("Details of the book " +
activeBook.getTitle() + " refreshed");
}
public void refreshPage()
{
/* updated page display */
System.out.println("Page no " + pageNumber + " refreshed");
}
}
/*
* The classes for User and Book simply hold data and
* provide little functionality.
* This class represents the Book which is a simple POJO
*/
class Book {
private int bookId;
private String details;
private String title;
public Book(int id, String details, String title)
{
bookId = id;
this.details = details;
this.title = title;
}
public int getId()
{
return bookId;
}
public void setId(int id)
{
bookId = id;
}
public String getDetails()
{
return details;
}
public void setDetails(String details)
{
this.details = details;
}
public String getTitle()
{
return title;
}
public void setTitle(String title)
{
this.title = title;
}
}
/*
* This class represents the User which is a simple POJO
*/
class User {
private int userId;
private String name;
private String details;
public void renewMembership()
{
}
public User(int id, String details, String name)
{
this.userId = id;
this.details = details;
this.name = name;
}
public int getId()
{
return userId;
}
public void setId(int id)
{
userId = id;
}
public String getDetails()
{
return details;
}
public void setDetails(String details)
{
this.details = details;
}
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
}
// This class is used to test the Application
public class AppTest {
public static void main(String[] args)
{
OnlineReaderSystem onlineReaderSystem = new OnlineReaderSystem();
Book dsBook = new Book(1, "It contains Data Structures", "Ds");
Book algoBook = new Book(2, "It contains Algorithms", "Algo");
onlineReaderSystem.getLibrary().addBook(dsBook);
onlineReaderSystem.getLibrary().addBook(algoBook);
User user1 = new User(1, " ", "Ram");
User user2 = new User(2, " ", "Gopal");
onlineReaderSystem.getUserManager().addUser(user1);
onlineReaderSystem.getUserManager().addUser(user2);
onlineReaderSystem.setActiveBook(algoBook);
onlineReaderSystem.setActiveUser(user1);
onlineReaderSystem.getDisplay().turnPageForward();
onlineReaderSystem.getDisplay().turnPageForward();
onlineReaderSystem.getDisplay().turnPageBackward();
}
}知识付费源码系统类图:聚合和多重性是设计类图时需要考虑的两个重要问题。让我们来详细了解一下。
聚合,
聚合只是表示一种关系，其中一件事可以独立于其他事存在。它意味着在定义类时创建或组合不同的抽象。聚合表示为类图中关系的一部分。在下面的图中，我们可以看到聚合是由一个指向超类的菱形末端的边表示的。“图书管理系统”是由各种类组成的超类。
这些类是User、Book和Librarian。此外，对于“Account”类，“User”是一个超类。所有这些，共享一种关系，这些关系被称为聚合关系。
多重性,
多重性意味着一个类的元素数量与另一个类相关联。这些关系可以是一对一、多对多、多对一或一对多。用来表示我们使用的一个元素1，表示我们使用的零元素0，以及我们使用的许多元素＊． 我们可以从图表中看到;许多用户与表示的许多书相关联＊这表示多对多类型的关系。一个用户只有一个用1表示的帐户，这表示a一对一的类型的关系。
知识付费系统类图简单地描述了知识管理系统类的结构、属性、方法或操作、对象之间的关系。
