conn = DBUtils.getConnection();     //獲取數據庫連接
            pstmt = conn.prepareStatement(sql1);//根據sql1創建PreparedStatement
            pstmt.setString(1, userId);         //設置參數
            pstmt.setString(2, listId);         //設置參數
            pstmt.executeUpdate();              //執行刪除
            pstmt.close();                      //關閉
            pstmt = conn.prepareStatement(sql2);//根據sql2創建PreparedStatement
            pstmt.setString(1, userId);         //設置參數
            pstmt.setString(2, listId);         //設置參數
            pstmt.executeUpdate();              //執行刪除
        } catch (SQLException e) {
            System.out.println(e.toString());
        } finally {
            DBUtils.close(pstmt);               //關閉PreparedStatement
            DBUtils.close(conn);                //關閉連接
        }
    }

    //更新任務列表
    void updateList(String userId, String listId, String listName) {
        String sql = "update task_lists set listname = ? where userid = ? and id = ?";   //定義SQL語句
        Connection conn = null;                 //聲明Connection對象
        PreparedStatement pstmt = null;         //聲明PreparedStatement對象
        try {
            conn = DBUtils.getConnection();     //獲取數據庫連接
            pstmt = conn.prepareStatement(sql); //根據sql創建PreparedStatement
            pstmt.setString(1, listName);       //設置參數
            pstmt.setString(2, userId);         //設置參數
            pstmt.setString(3, listId);         //設置參數
            pstmt.executeUpdate();              //執行更新
        } catch (SQLException e) {
            System.out.println(e.toString());
        } finally {
            DBUtils.close(pstmt);               //關閉PreparedStatement
            DBUtils.close(conn);                //關閉連接
        }
    }

    //添加任務
    void addTask(String userId, String listId, String taskName) {
        String sql = "insert into task_tasks(userid, listid, taskname) values(?,?,?)";   //定義SQL語句
        Connection conn = null;                 //聲明Connection對象
        PreparedStatement pstmt = null;         //聲明PreparedStatement對象
        try {
            conn = DBUtils.getConnection();     //獲取數據庫連接
            pstmt = conn.prepareStatement(sql); //根據sql創建PreparedStatement
            pstmt.setString(1, userId);         //設置參數
            pstmt.setString(2, listId);         //設置參數
            pstmt.setString(3, taskName);       //設置參數
            pstmt.executeUpdate();              //執行插入
        } catch (SQLException e) {
            System.out.println(e.toString());
        } finally {
            DBUtils.close(pstmt);               //關閉PreparedStatement
            DBUtils.close(conn);                //關閉連接
        }
    }

    //刪除任務
    void delTask(String userId, String taskId) {
        String sql = "delete from task_tasks where userid = ? and id = ?";   //定義SQL語句
        Connection conn = null;                 //聲明Connection對象
        PreparedStatement pstmt = null;         //聲明PreparedStatement對象
        try {
            conn = DBUtils.getConnection();     //獲取數據庫連接
            pstmt = conn.prepareStatement(sql); //根據sql創建PreparedStatement
            pstmt.setString(1, userId);         //設置參數
            pstmt.setString(2, taskId);         //設置參數
            pstmt.executeUpdate();              //執行刪除
        } catch (SQLException e) {
            System.out.println(e.toString());
        } finally {
            DBUtils.close(pstmt);               //關閉PreparedStatement
            DBUtils.close(conn);                //關閉連接
        }
    }

    //更新任務
    void updateTask(String userId, String taskId, String taskName) {
        String sql = "update task_tasks set taskname = ? where userid = ? and id = ?";   //定義SQL語句
        Connection conn = null;                 //聲明Connection對象
        PreparedStatement pstmt = null;         //聲明PreparedStatement對象
        try {
            conn = DBUtils.getConnection();     //獲取數據庫連接
            pstmt = conn.prepareStatement(sql); //根據sql創建PreparedStatement
            pstmt.setString(1, taskName);       //設置參數
            pstmt.setString(2, userId);         //設置參數
            pstmt.setString(3, taskId);         //設置參數
            pstmt.executeUpdate();              //執行更新
        } catch (SQLException e) {
            System.out.println(e.toString());
        } finally {
            DBUtils.close(pstmt);               //關閉PreparedStatement
            DBUtils.close(conn);                //關閉連接
        }
    }
%>
<%
    out.clear();                                            //清空當前的輸出內容（空格和換行符）
    request.setCharacterEncoding("UTF-8");                  //設置請求字符集為UTF-8
    String userId = (String) session.getAttribute(sessionKey);  //獲取當前登錄用戶編號

    String action = request.getParameter("action");         //獲取title

    //根據action參數不同執行不同的操作
    if ("login".equals(action)) {                           //登錄操作
        String userName = request.getParameter("userName");
        String password = request.getParameter("password");
        String result = login(userName, password, session);
        out.print(result);
    } else if ("logout".equals(action)) {                   //退出操作
        session.removeAttribute(sessionKey);
    } else if ("getLists".equals(action)) {                 //獲取任務列表
        out.print(getLists(userId));
    } else if ("getTasks".equals(action)) {                 //獲取任務
        String listId = request.getParameter("listId");
        out.print(getTasks(userId, listId));
    } else if ("changeTaskStatus".equals(action)) {         //改變任務狀態
        String taskId = request.getParameter("taskId");
        String status = request.getParameter("status");
        changeTaskStatus(userId, taskId, status);
        out.print("任務狀態修改成功。");
    } else if ("addList".equals(action)) {                  //添加任務列表
        String listName = request.getParameter("listName");
        addList(userId, listName);
        out.print("列表添加成功。");
    } else if ("delList".equals(action)) {                  //刪除任務列表
        String listId = request.getParameter("listId");
        delList(userId, listId);
        out.print("列表刪除成功。");
    } else if ("updateList".equals(action)) {               //更新任務列表
        String listId = request.getParameter("listId");
        String listName = request.getParameter("listName");
        updateList(userId, listId, listName);
        out.print("列表更新成功。");
    } else if ("addTask".equals(action)) {                  //添加任務
        String listId = request.getParameter("listId");
        String taskName = request.getParameter("taskName");
        addTask(userId, listId, taskName);
        out.print("任務添加成功。");
    } else if ("delTask".equals(action)) {                  //刪除任務
        String taskId = request.getParameter("taskId");
        delTask(userId, taskId);
        out.print("任務刪除成功。");
    } else if ("updateTask".equals(action)) {               //更新任務
        String taskId = request.getParameter("taskId");
        String taskName = request.getParameter("taskName");
        updateTask(userId, taskId, taskName);
        out.print("任務更新成功。");
    }
%>