Design data structures for an online book reader system

最新推荐文章于 2023-09-24 16:45:00 发布

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本文介绍了一个在线电子图书阅读系统的底层数据结构设计，包括书籍类(MyBook)与在线阅读器类(MyOnlineReader)的实现。书籍类负责存储作者、标题、页数等内容信息，并提供书签功能；在线阅读器类则实现了打开书籍、翻页、添加书签等操作。

如题，设计一个在线电子图书阅读系统，主要设计底层数据结构。那不说了，直接贴代码吧。

public class MyBook {
    private final String author;
    private final String title;
    private final int number_pages;
    private final List<String> content;
    private final List<Integer> chapterIndex;
 
    private List<Integer> bookmarks;
 
    public MyBook(String author, String title, int number_pages,
            ArrayList<String> content, List<Integer> chapterIndex) {
        super();
        this.author = author;
        this.title = title;
        this.number_pages = number_pages;
        this.content = content;
        this.chapterIndex = chapterIndex;
    }
 
    public void addBookMark(int pageNumber) {
        bookmarks.add(pageNumber);
    }
 
    public List<Integer> getBookmarks() {
        return bookmarks;
    }
 
    public String getPage(int pageNumber) {
        return content.get(pageNumber);
    }
}
 
public class MyOnlineReader {
    private Map<String, Map<String, MyBook>> bookMap;
    private MyBook currentBook;
    private int currentPage;
 
    public void openBook(String author, String title) {
        currentBook = bookMap.get(author).get(title);
        List<Integer> bookmarks = currentBook.getBookmarks();
        if (bookmarks.isEmpty())
            bookmarks.add(0);
        currentPage = bookmarks.get(bookmarks.size() - 1);
        System.out.println(currentBook.getPage(currentPage));
    }
 
    private boolean finished() {
        return currentPage == currentBook.number_pages - 1;
    }
 
    public void addBookMark() {
        if (!currentBook.getBookmarks().contains(currentPage))
            currentBook.addBookMark(currentPage);
    }
 
    public void displayAllBookMark() {
        System.out.println(currentBook.getBookmarks());
    }
 
    public void nextPage() {
        List<Integer> bookmarks = currentBook.getBookmarks();
        bookmarks.remove(currentPage);
        currentPage = finished() ? 
                currentPage : currentPage + 1;
        bookmarks.add(currentPage);
        System.out.println(currentBook.getPage(currentPage));
    }
 
    public void previousPage() {
        List<Integer> bookmarks = currentBook.getBookmarks();
        bookmarks.remove(currentPage);
        currentPage = currentPage == 0 ? 
                currentPage : currentPage - 1;
        bookmarks.add(currentPage);
        System.out.println(currentBook.getPage(currentPage));
    }
 
    public void goToPage(int pageNumber) {
        if (pageNumber < 0 || pageNumber >= currentBook.number_pages)
            return;
        List<Integer> bookmarks = currentBook.getBookmarks();
        bookmarks.remove(currentPage);
        currentPage = pageNumber;
        bookmarks.add(currentPage);
        System.out.println(currentBook.getPage(currentPage));
    }
}


官方给了一个标准答案，也一起贴了吧，精妙之处是将所有的Book和Users设为静态，这样，每一个Book和User都可以共享到其他对象的资源。
public class Book {
    private long ID;
    private String details;
    private static Set<Book> books;
 
    public long getID() {
        return ID;
    }
 
    public Book(long id, String details) {
    }
 
    public static void addBook(long iD, String details) {
        books.add(new Book(iD, details));
    }
 
    public void update() {
    }
 
    public static void delete(Book b) {
        books.remove(b);
    }
 
    public static Book find(long id) {
        for (Book b : books)
            if (b.getID() == id)
                return b;
        return null;
    }
}
 
public class User {
    private long ID;
    private String details;
    private int accountType;
    private static Set<User> users;
 
    public long getID() {
        return ID;
    }
 
    public Book searchLibrary(long id) {
        return Book.find(id);
    }
 
    public void renewMembership() {
    }
 
    public static User find(long ID) {
        for (User u : users) {
            if (u.getID() == ID)
                return u;
        }
        return null;
    }
 
    public static void addUser(long ID, String details, 
            int accountType) {
        users.add(new User(ID, details, accountType));
    }
 
    public User(long iD, String details, int accountType) {
    }
}
 
public class OnlineReaderSystem {
    private Book b;
    private User u;
 
    public OnlineReaderSystem(Book b, User u) {
    }
 
    public void listenRequest() {
    }
 
    public Book searchBook(long ID) {
        return Book.find(ID);
    }
 
    public User searchUser(long ID) {
        return User.find(ID);
    }
 
    public void display() {
    }
}