帮我找javawebMVC模式实现CRUD操作代码及运行图

好的，以下是一个简单的JavaWeb MVC模式实现CRUD操作的代码示例：

Model类（User.java）：

public class User {
    private int id;
    private String name;
    private int age;

    public User() {}

    public User(int id, String name, int age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    // getter and setter methods
    // ...

}

DAO类（UserDAO.java）：

public class UserDAO {
    private Connection conn;

    public UserDAO() {
        // 初始化数据库连接
        // ...
    }

    public List<User> getAllUsers() {
        List<User> users = new ArrayList<User>();
        // 执行查询语句，并将结果封装到List<User>中
        // ...
        return users;
    }

    public User getUserById(int id) {
        User user = null;
        // 执行查询语句，并将结果封装到User对象中
        // ...
        return user;
    }

    public void addUser(User user) {
        // 执行插入语句，将User对象中的数据插入到数据库中
        // ...
    }

    public void updateUser(User user) {
        // 执行更新语句，更新数据库中对应的数据
        // ...
    }

    public void deleteUser(int id) {
        // 执行删除语句，删除数据库中对应的数据
        // ...
    }

    // 关闭数据库连接
    // ...
}

Controller类（UserController.java）：

public class UserController extends HttpServlet {
    private UserDAO userDao;

    public UserController() {
        userDao = new UserDAO();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String action = request.getServletPath();

        switch (action) {
            case "/new":
                showNewForm(request, response);
                break;
            case "/edit":
                showEditForm(request, response);
                break;
            case "/delete":
                deleteUser(request, response);
                break;
            case "/view":
                viewUser(request, response);
                break;
            default:
                listUsers(request, response);
                break;
        }
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String action = request.getServletPath();

        switch (action) {
            case "/new":
                addUser(request, response);
                break;
            case "/edit":
                updateUser(request, response);
                break;
            default:
                break;
        }
    }

    private void listUsers(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        List<User> users = userDao.getAllUsers();
        request.setAttribute("users", users);
        RequestDispatcher dispatcher = request.getRequestDispatcher("user-list.jsp");
        dispatcher.forward(request, response);
    }

    private void showNewForm(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        RequestDispatcher dispatcher = request.getRequestDispatcher("user-form.jsp");
        dispatcher.forward(request, response);
    }

    private void showEditForm(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int id = Integer.parseInt(request.getParameter("id"));
        User existingUser = userDao.getUserById(id);
        RequestDispatcher dispatcher = request.getRequestDispatcher("user-form.jsp");
        request.setAttribute("user", existingUser);
        dispatcher.forward(request, response);
    }

    private void addUser(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String name = request.getParameter("name");
        int age = Integer.parseInt(request.getParameter("age"));
        User newUser = new User(0, name, age);
        userDao.addUser(newUser);
        response.sendRedirect("list");
    }

    private void updateUser(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int id = Integer.parseInt(request.getParameter("id"));
        String name = request.getParameter("name");
        int age = Integer.parseInt(request.getParameter("age"));
        User existingUser = new User(id, name, age);
        userDao.updateUser(existingUser);
        response.sendRedirect("list");
    }

    private void deleteUser(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int id = Integer.parseInt(request.getParameter("id"));
        userDao.deleteUser(id);
        response.sendRedirect("list");
    }

    private void viewUser(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int id = Integer.parseInt(request.getParameter("id"));
        User user = userDao.getUserById(id);
        request.setAttribute("user", user);
        RequestDispatcher dispatcher = request.getRequestDispatcher("user-view.jsp");
        dispatcher.forward(request, response);
    }
}

View视图（user-list.jsp、user-form.jsp、user-view.jsp）：

user-list.jsp：

<html>
<head>
    <title>User List</title>
</head>
<body>
    <h1>User List</h1>
    <table border="1">
        <tr>
            <th>ID</th>
            <th>Name</th>
            <th>Age</th>
            <th>Actions</th>
        </tr>
        <c:forEach items="${users}" var="user">
            <tr>
                <td>${user.id}</td>
                <td>${user.name}</td>
                <td>${user.age}</td>
                <td>
                    <a href="view?id=${user.id}">View</a>
                    <a href="edit?id=${user.id}">Edit</a>
                    <a href="delete?id=${user.id}" onclick="return confirm('Are you sure you want to delete this user?')">Delete</a>
                </td>
            </tr>
        </c:forEach>
    </table>
    <br>
    <a href="new">Add User</a>
</body>
</html>

user-form.jsp：

<html>
<head>
    <title>User Form</title>
</head>
<body>
    <h1>User Form</h1>
    <form action="${action}" method="POST">
        <c:if test="${not empty user.id}">
            <input type="hidden" name="id" value="${user.id}">
        </c:if>
        <label for="name">Name:</label>
        <input type="text" name="name" value="${not empty user.name ? user.name : ''}">
        <br>
        <label for="age">Age:</label>
        <input type="number" name="age" value="${not empty user.age ? user.age : ''}">
        <br>
        <input type="submit" value="Save">
        <a href="list">Cancel</a>
    </form>
</body>
</html>

user-view.jsp：

<html>
<head>
    <title>User View</title>
</head>
<body>
    <h1>User View</h1>
    <table border="1">
        <tr>
            <th>ID</th>
            <td>${user.id}</td>
        </tr>
        <tr>
            <th>Name</th>
            <td>${user.name}</td>
        </tr>
        <tr>
            <th>Age</th>
            <td>${user.age}</td>
        </tr>
    </table>
    <br>
    <a href="list">Back to List</a>
</body>
</html>

这里只是简单的示例，实际上还需要进行一些参数验证、异常处理等操作，以确保系统的安全和稳定性。

至于运行图，由于我无法直接在这里插入图片，您可以在本地运行代码后，在浏览器中查看效果。