设计实现一个图书管理系统。图书信息存放到一个数据库中，图书包含信息：图书号、图书名、作者、价格。请实现对图书的增删改查操作。采用JavaBean+Servlet+JSP+DAO的Web架构设计该系统

好的，下面是采用JavaBean+Servlet+JSP+DAO的Web架构设计的图书管理系统。

首先，我们需要建立一个图书Bean，包含以下字段：

public class Book {
    private int id;
    private String name;
    private String author;
    private double price;
    // 构造函数、getters 和 setters 略
}

接下来，我们可以编写一个简单的 DAO 类，使用 JDBC 来实现增删改查操作。例如：

public class BookDAO {
    public static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
    public static final String DB_URL = "jdbc:mysql://localhost:3306/books";

    public static final String USER = "root";
    public static final String PASS = "password";

    public List<Book> getAllBooks() throws SQLException {
        List<Book> books = new ArrayList<>();
        Connection conn = null;
        Statement stmt = null;
        try {
            Class.forName(JDBC_DRIVER);
            conn = DriverManager.getConnection(DB_URL, USER, PASS);
            stmt = conn.createStatement();
            String sql = "SELECT * FROM book";
            ResultSet rs = stmt.executeQuery(sql);
            while (rs.next()) {
                Book book = new Book();
                book.setId(rs.getInt("id"));
                book.setName(rs.getString("name"));
                book.setAuthor(rs.getString("author"));
                book.setPrice(rs.getDouble("price"));
                books.add(book);
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } finally {
            if (stmt != null) stmt.close();
            if (conn != null) conn.close();
        }
        return books;
    }

    public void addBook(Book book) throws SQLException {
        Connection conn = null;
        PreparedStatement stmt = null;
        try {
            Class.forName(JDBC_DRIVER);
            conn = DriverManager.getConnection(DB_URL, USER, PASS);
            String sql = "INSERT INTO book (name, author, price) VALUES (?, ?, ?)";
            stmt = conn.prepareStatement(sql);
            stmt.setString(1, book.getName());
            stmt.setString(2, book.getAuthor());
            stmt.setDouble(3, book.getPrice());
            stmt.executeUpdate();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } finally {
            if (stmt != null) stmt.close();
            if (conn != null) conn.close();
        }
    }

    public void updateBook(int id, Book book) throws SQLException {
        Connection conn = null;
        PreparedStatement stmt = null;
        try {
            Class.forName(JDBC_DRIVER);
            conn = DriverManager.getConnection(DB_URL, USER, PASS);
            String sql = "UPDATE book SET name=?, author=?, price=? WHERE id=?";
            stmt = conn.prepareStatement(sql);
            stmt.setString(1, book.getName());
            stmt.setString(2, book.getAuthor());
            stmt.setDouble(3, book.getPrice());
            stmt.setInt(4, id);
            stmt.executeUpdate();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } finally {
            if (stmt != null) stmt.close();
            if (conn != null) conn.close();
        }
    }

    public void deleteBook(int id) throws SQLException {
        Connection conn = null;
        PreparedStatement stmt = null;
        try {
            Class.forName(JDBC_DRIVER);
            conn = DriverManager.getConnection(DB_URL, USER, PASS);
            String sql = "DELETE FROM book WHERE id=?";
            stmt = conn.prepareStatement(sql);
            stmt.setInt(1, id);
            stmt.executeUpdate();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } finally {
            if (stmt != null) stmt.close();
            if (conn != null) conn.close();
        }
    }
}

这个 DAO 类使用 MySQL 数据库来存储图书信息，提供了四个方法：

- getAllBooks：获取所有图书信息
- addBook：添加一本新书
- updateBook：更新一本图书的信息
- deleteBook：删除一本图书

接下来，我们可以编写一个 Servlet 类，处理 HTTP 请求并调用 DAO 类的方法来实现增删改查操作。例如：

public class BookServlet extends HttpServlet {
    private BookDAO dao = new BookDAO();

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        List<Book> books = null;
        try {
            books = dao.getAllBooks();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        request.setAttribute("books", books);
        request.getRequestDispatcher("/book_list.jsp").forward(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String action = request.getParameter("action");
        if ("add".equals(action)) {
            String name = request.getParameter("name");
            String author = request.getParameter("author");
            double price = Double.parseDouble(request.getParameter("price"));
            Book book = new Book();
            book.setName(name);
            book.setAuthor(author);
            book.setPrice(price);
            try {
                dao.addBook(book);
            } catch (SQLException e) {
                e.printStackTrace();
            }
        } else if ("update".equals(action)) {
            int id = Integer.parseInt(request.getParameter("id"));
            String name = request.getParameter("name");
            String author = request.getParameter("author");
            double price = Double.parseDouble(request.getParameter("price"));
            Book book = new Book();
            book.setName(name);
            book.setAuthor(author);
            book.setPrice(price);
            try {
                dao.updateBook(id, book);
            } catch (SQLException e) {
                e.printStackTrace();
            }
        } else if ("delete".equals(action)) {
            int id = Integer.parseInt(request.getParameter("id"));
            try {
                dao.deleteBook(id);
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        response.sendRedirect(request.getContextPath() + "/book");
    }
}

这个 Servlet 类处理了 GET 和 POST 请求，GET 请求返回所有图书信息，POST 请求根据参数判断是添加、更新还是删除图书信息。

最后，我们可以编写一个 JSP 页面，展示所有图书信息，并提供表单来添加、更新和删除图书信息。例如：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>图书管理系统</title>
</head>
<body>
    <h1>图书列表</h1>
    <table border="1">
        <tr>
            <th>图书号</th>
            <th>图书名</th>
            <th>作者</th>
            <th>价格</th>
            <th>操作</th>
        </tr>
        <c:forEach items="${books}" var="book">
            <tr>
                <td>${book.id}</td>
                <td>${book.name}</td>
                <td>${book.author}</td>
                <td>${book.price}</td>
                <td>
                    <form action="${pageContext.request.contextPath}/book" method="post">
                        <input type="hidden" name="id" value="${book.id}">
                        <input type="hidden" name="action" value="update">
                        <input type="text" name="name" value="${book.name}">
                        <input type="text" name="author" value="${book.author}">
                        <input type="text" name="price" value="${book.price}">
                        <input type="submit" value="更新">
                    </form>
                    <form action="${pageContext.request.contextPath}/book" method="post">
                        <input type="hidden" name="id" value="${book.id}">
                        <input type="hidden" name="action" value="delete">
                        <input type="submit" value="删除">
                    </form>
                </td>
            </tr>
        </c:forEach>
    </table>
    <h1>添加图书</h1>
    <form action="${pageContext.request.contextPath}/book" method="post">
        <input type="hidden" name="action" value="add">
        <label>图书名：</label><input type="text" name="name"><br>
        <label>作者：</label><input type="text" name="author"><br>
        <label>价格：</label><input type="text" name="price"><br>
        <input type="submit" value="添加">
    </form>
</body>
</html>

这个 JSP 页面展示了所有图书信息，并提供表单来添加、更新和删除图书信息。

最后，我们需要将这些组件组合在一起，例如在 web.xml 中配置 Servlet 和 JSP 的映射关系：

<servlet>
    <servlet-name>BookServlet</servlet-name>
    <servlet-class>com.example.BookServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>BookServlet</servlet-name>
    <url-pattern>/book</url-pattern>
</servlet-mapping>

<welcome-file-list>
    <welcome-file>book.jsp</welcome-file>
</welcome-file-list>

这个配置将 BookServlet 映射到 /book 路径，将 book.jsp 设置为默认欢迎页面。

这样，我们就完成了采用JavaBean+Servlet+JSP+DAO的Web架构设计的图书管理系统。您可以使用 Tomcat 等 Web 服务器来部署和运行这个系统，然后在浏览器中访问 /book 路径来使用它。