Question

我已经编写了delete方法的servlet和dao部分。一旦我想在jsp页面中使用该方法，它将返回ERROR 500 / ERROR 404。

我正在使用tomcat 7，Java 7和Windows10。正在运行oracle。我尝试使用ajax链接servlet删除方法，但仍然无法正常工作。

// deleteStaffServelt
public class DeleteStaffServlet extends HttpServlet {

    enter code here
    /**
     *
     */
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        String ids = request.getParameter("userId");

        int deleteId = Integer.parseInt(ids);
        StaffDao staffDao = new StaffDao();
        staffDao.delete(deleteId);
        response.sendRedirect("deleteStaffServlet?id=" + deleteId);
    }

    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

// delete method in Dao
public void delete(int id) {
        try {
            String sql = "delete from ZZZ_EMPLOYEES where ZE_ID = " + id;
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setInt(1, id);
            ps.executeUpdate();
            ps.close();
        } catch (Exception ex) {
            ex.printStackTrace();
        }

// jsp
<body>
    <form action="listServletTwo">
        <table border="0" cellspacing="0">
            <tr>
                <td>社員No. <input name="noStart" type="text" size="8" />
                    &nbsp;～&nbsp; <input name="noEnd" type="text" size="8" /> <input
                    type="submit" value="検索" />
                </td>
                <td>社員名. <input name="name" type="text" size="20" /> <input
                    type="submit" value="検索" />
                </td>
            </tr>
        </table>
        </br>
        <%
            List<Staff> list1 = (List<Staff>) session.getAttribute("list");
            if (list1 != null) {
        %>
        <table border="1" cellspacing="0">
            <tr bgcolor="pink">
                <td>社員No.</td>
                <td>ユーザーID</td>
                <td>社員名</td>
                <td>削除機能</td>
                <td>更新機能</td>
            </tr>
            <%
                for (Staff s : list1) {
            %>
            <tr>
                <td id="<%=s.getId()%>"><%=s.getId()%></td>
                <td><%=s.getNo()%></td>
                <td><%=s.getName()%></td>
                <td><a href="deleteStaffServlet?id=<%=s.getId()%>" name="userId">Delete</a></td>
                <td>名前:<input name="name" type="text" size="10" /> ユーザーID:<input
                    name="name" type="text" size="10" />
                    <input type="submit" value="Edit" name="edit" onclick="editRecord(<%=s.getId()%>);">
                </td>
            </tr>
            <%
                }
                }
                session.removeAttribute("list");
            %>

        </table>
    </form>

结果为HTTP状态500 –内部服务器错误 java.lang.NumberFormatException：空

Answer 1

在这里，<a href="deleteStaffServlet?id=<%=s.getId()%>" name="userId">Delete</a>，您已经使用过id=<%=s.getId()%>，即：您正在参数<%=s.getId()%>中获得值id，但是在您的servlet中，您正在获取参数使用request.getParameter("userId");只需将其更改为request.getParameter("id");。

此外，您的delete query是错误的，如下所示：

// delete method in Dao
public void delete(int id) {
        try {
          //you have to give placeholder(?) in query not the value 
            String sql = "delete from ZZZ_EMPLOYEES where ZE_ID =?";
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setInt(1, id);
            ps.executeUpdate();
            ps.close();
        } catch (Exception ex) {
            ex.printStackTrace();
        } 
     }

我不确定您在这里做什么：

response.sendRedirect("deleteStaffServlet?id=" + deleteId);

但是，我认为您已经从表中删除了必需的row，因此无需再次执行此操作。因此，只需将其更改为以下内容即可：

 response.sendRedirect("yourjsppage");

谁能在jsp和servlet中修复我的删除功能，请

1 个答案: