Java web图书管理系统代码怎么写

这是一个比较大的项目，需要涉及到前端、后端和数据库等多个方面的知识。以下是一个简单的Java web图书管理系统的代码示例，仅供参考：

1. 创建数据库表

首先需要创建相应的数据库表，例如：

CREATE TABLE `book` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `author` varchar(255) NOT NULL,
  `price` double NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

2. 编写JavaBean类

在Java中创建一个Book类，用于封装书籍的相关信息，例如：

public class Book {
    private int id;
    private String name;
    private String author;
    private double price;

    // 省略get/set方法
}

3. 编写DAO类

创建一个BookDAO类，用于实现对数据库的增删改查操作，例如：

public class BookDAO {
    // JDBC连接
    private Connection conn = null;
    // SQL语句执行器
    private PreparedStatement pstmt = null;
    // 结果集
    private ResultSet rs = null;

    // 构造方法中初始化数据库连接
    public BookDAO() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/book", "root", "123456");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    // 添加书籍
    public boolean add(Book book) {
        try {
            String sql = "INSERT INTO book(name, author, price) VALUES(?, ?, ?)";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, book.getName());
            pstmt.setString(2, book.getAuthor());
            pstmt.setDouble(3, book.getPrice());
            int result = pstmt.executeUpdate();
            if (result > 0) {
                return true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

    // 根据ID删除书籍
    public boolean delete(int id) {
        try {
            String sql = "DELETE FROM book WHERE id=?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            int result = pstmt.executeUpdate();
            if (result > 0) {
                return true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

    // 根据ID修改书籍信息
    public boolean update(Book book) {
        try {
            String sql = "UPDATE book SET name=?, author=?, price=? WHERE id=?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, book.getName());
            pstmt.setString(2, book.getAuthor());
            pstmt.setDouble(3, book.getPrice());
            pstmt.setInt(4, book.getId());
            int result = pstmt.executeUpdate();
            if (result > 0) {
                return true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

    // 根据ID查询书籍信息
    public Book findById(int id) {
        Book book = new Book();
        try {
            String sql = "SELECT * FROM book WHERE id=?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            rs = pstmt.executeQuery();
            if (rs.next()) {
                book.setId(rs.getInt("id"));
                book.setName(rs.getString("name"));
                book.setAuthor(rs.getString("author"));
                book.setPrice(rs.getDouble("price"));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return book;
    }

    // 查询所有书籍信息
    public List<Book> findAll() {
        List<Book> list = new ArrayList<>();
        try {
            String sql = "SELECT * FROM book";
            pstmt = conn.prepareStatement(sql);
            rs = pstmt.executeQuery();
            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"));
                list.add(book);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return list;
    }

    // 关闭数据库连接
    public void close() {
        try {
            if (rs != null) {
                rs.close();
            }
            if (pstmt != null) {
                pstmt.close();
            }
            if (conn != null) {
                conn.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

4. 编写Servlet类

创建一个BookServlet类，用于接收前端的请求并调用DAO类中的方法进行处理，例如：

@WebServlet("/book")
public class BookServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 获取请求参数
        String action = request.getParameter("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"));

        // 创建DAO对象
        BookDAO dao = new BookDAO();

        // 根据请求参数调用相应的方法
        if (action.equals("add")) {
            // 添加书籍
            Book book = new Book();
            book.setName(name);
            book.setAuthor(author);
            book.setPrice(price);
            boolean result = dao.add(book);
            if (result) {
                response.getWriter().print("添加成功");
            } else {
                response.getWriter().print("添加失败");
            }
        } else if (action.equals("delete")) {
            // 删除书籍
            boolean result = dao.delete(id);
            if (result) {
                response.getWriter().print("删除成功");
            } else {
                response.getWriter().print("删除失败");
            }
        } else if (action.equals("update")) {
            // 修改书籍信息
            Book book = new Book();
            book.setId(id);
            book.setName(name);
            book.setAuthor(author);
            book.setPrice(price);
            boolean result = dao.update(book);
            if (result) {
                response.getWriter().print("修改成功");
            } else {
                response.getWriter().print("修改失败");
            }
        } else if (action.equals("findById")) {
            // 根据ID查询书籍信息
            Book book = dao.findById(id);
            response.getWriter().print(book);
        } else if (action.equals("findAll")) {
            // 查询所有书籍信息
            List<Book> list = dao.findAll();
            response.getWriter().print(list);
        }

        // 关闭数据库连接
        dao.close();
    }
}

5. 编写前端页面

最后，创建一个前端页面，用于向Servlet发送请求，并显示相应的结果。例如：

<!DOCTYPE html>
<html>
<head>
    <title>图书管理系统</title>
    <meta charset="UTF-8">
</head>
<body>
    <form action="book" method="post">
        <input type="hidden" name="action" value="add">
        <p>书名：<input type="text" name="name"></p>
        <p>作者：<input type="text" name="author"></p>
        <p>价格：<input type="text" name="price"></p>
        <p><input type="submit" value="添加"></p>
    </form>

    <form action="book" method="post">
        <input type="hidden" name="action" value="delete">
        <p>ID：<input type="text" name="id"></p>
        <p><input type="submit" value="删除"></p>
    </form>

    <form action="book" method="post">
        <input type="hidden" name="action" value="update">
        <p>ID：<input type="text" name="id"></p>
        <p>书名：<input type="text" name="name"></p>
        <p>作者：<input type="text" name="author"></p>
        <p>价格：<input type="text" name="price"></p>
        <p><input type="submit" value="修改"></p>
    </form>

    <form action="book" method="post">
        <input type="hidden" name="action" value="findById">
        <p>ID：<input type="text" name="id"></p>
        <p><input type="submit" value="查询"></p>
    </form>

    <form action="book" method="post">
        <input type="hidden" name="action" value="findAll">
        <p><input type="submit" value="查询所有"></p>
    </form>
</body>
</html>

以上是一个简单的Java web图书管理系统的代码示例，仅供参考。实际开发中，需要根据具体需求进行修改和完善。