java - 在 java servlet 中运行覆盖的 doPost 方法时遇到问题
问题描述
下面的代码来自jsp文件。
<table class="table table-striped table-hover table-responsive ezoo-datatable">
<thead>
<tr>
<th class="text-center">Schedule ID</th>
<th class="text-center">Feeding Time</th>
<th class="text-center">Recurrence</th>
<th class="text-center">Notes</th>
<th class="text-center">Food</th>
<th class="text-center">Animal ID</th>
<th></th>
</tr>
</thead>
<% int counter = 0; %>
<tbody>
<form action="feedingSchedules" method="post">
<c:forEach var="schedule" items="${feeding_schedules}">
<tr>
<td><c:out value="${schedule.schedule_ID}" /></td>
<td><c:out value="${schedule.feeding_time}" /></td>
<td><c:out value="${schedule.recurrence}" /></td>
<td><c:out value="${schedule.notes}" /></td>
<td><c:out value="${schedule.food}" /></td>
<td><c:out value="${schedule.animalID}" /></td>
<td><button class="btn-danger-stale" name="btn${counter}" value="val${counter}">Delete Schedule</button></td>
<% counter++; %>
</tr>
</c:forEach>
<input type="hidden" name="numSchedules" value="${counter}"/>
</form>
</tbody>
</table>
此代码构建一个数据表。我有一个 servlet,通过调用 dao 方法从数据库中获取数据来填充表。我需要向表中添加按钮以删除与按钮对应的行。我有按钮,但我不确定如何让它们执行实际删除。
@WebServlet(description = "This servlet is the main interface into the Feeding Schedules System", urlPatterns = { "/feedingSchedules" })
public class FeedingSchedulesServlet extends HttpServlet{
private static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// Grab a list of Animals from the Database
FeedingScheduleDAO dao = DAOUtilities.getFeedingScheduleDao();
List<FeedingSchedule> schedules = dao.getAllSchedules();
// Populate the list into a variable that will be stored in the session
request.getSession().setAttribute("feeding_schedules", schedules);
request.getRequestDispatcher("feedingScheduleHome.jsp").forward(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
FeedingScheduleDAO dao = DAOUtilities.getFeedingScheduleDao();
List<FeedingSchedule> schedules = dao.getAllSchedules();
//Get Parameters
System.out.println("got here");
int count = Integer.parseInt(request.getParameter("numSchedules"));
for(int i = 0; i < count; i++) {
String btn = null;
btn = request.getParameter("btn" + i);
if(btn == ("val" + i)) {
System.out.println("got here");
// call delete method from DAO
try {
dao.deleteSchedule(schedules.get(i));
request.getSession().setAttribute("message", "Schedule successfully deleted");
request.getSession().setAttribute("messageClass", "alert-success");
response.sendRedirect("feedingSchedules");
} catch (Exception e) {
e.printStackTrace();
request.getSession().setAttribute("message", "There was a problem deleting the schedule at this time");
request.getSession().setAttribute("messageClass", "alert-danger");
request.getRequestDispatcher("feedingScheduleHome.jsp").forward(request, response);
}
}
}
}
}
上面的代码是servlet。当我单击按钮时,我在覆盖的 doPost 方法中放置的打印行不会显示在控制台中,因此我不相信该方法被正确调用。有谁知道我做错了什么?我花了几个小时盯着这个,可以用一些新鲜的眼睛。
解决方案
分配id
给你的form
例如
<form id="myForm" action="feedingSchedules" method="post">
并更换
<button class="btn-danger-stale" name="btn${counter}" value="val${counter}">Delete Schedule</button>
和
<button class="btn-danger-stale" name="btn${counter}" value="val${counter}" onclick="document.getElementById('myForm').submit();">Delete Schedule</button>
或者,
id
如上所述为您的表单以及如下所述的按钮分配一个:
<button id="myButton" class="btn-danger-stale" name="btn${counter}" value="val${counter}">Delete Schedule</button>
并在您的 jsp 文件中添加以下 javascript:
var form = document.getElementById("myForm");
document.getElementById("myButton").addEventListener("click", function () {
form.submit();
});
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