【三层架构】举例说明表示层、业务层和数据层的bean包含哪些功能

一个简单的图书管理系统，其中包含图书馆的图书信息。我们将使用三层架构来实现这个系统，分别是表示层、业务层和数据层。现在我们来定义每个层次的Bean对象。

1. 表示层（Presentation Layer）Bean： 在表示层，我们可以定义一个"BookViewBean"来封装图书信息以展示给用户。这个Bean包含图书的名称和作者。

public class BookViewBean {
    private String title;
    private String author;

    // Getters and setters

    // Constructor
    public BookViewBean(String title, String author) {
        this.title = title;
        this.author = author;
    }
}

2. 业务层（Business Layer）Bean： 在业务层，我们可以定义一个"BookServiceBean"，它负责处理图书的业务逻辑，例如添加、删除、查找图书等操作。

public class BookServiceBean {
    // Method to add a new book
    public void addBook(String title, String author) {
        // Business logic to add a book to the database
    }

    // Method to delete a book
    public void deleteBook(String bookId) {
        // Business logic to delete a book from the database
    }

    // Method to search for books by title
    public List<BookViewBean> searchBooksByTitle(String title) {
        // Business logic to search for books in the database and return a list of BookViewBeans
        return new ArrayList<>();
    }
}

3. 数据层（Data Layer）Bean： 在数据层，我们可以定义一个"BookDAOBean"，它负责与数据库进行交互，执行对图书数据的读取、写入和更新操作。

public class BookDAOBean {
    // Method to add a new book to the database
    public void addBookToDatabase(String title, String author) {
        // Database interaction to add the book
    }

    // Method to delete a book from the database
    public void deleteBookFromDatabase(String bookId) {
        // Database interaction to delete the book
    }

    // Method to fetch books from the database based on title
    public List<BookViewBean> getBooksByTitleFromDatabase(String title) {
        // Database interaction to fetch books and convert them to BookViewBeans
        return new ArrayList<>();
    }
}