通过servlet将数据从数据库显示到完整日历—没有列出事件

这是我第一次使用。jsp和Netbeans。我试图创建一个利用完整日历的系统，用户可以选择月/年对，并显示谁在选定的月的哪一天休假。基本上，它将列出缺席的员工名称，而不是列出事件。我将把这些名称称为事件。

这里的问题是日历没有显示任何事件。我遵循了这个教程和这个问题(指的是我链接的教程)，但我似乎不能让它工作。日历在那里，但没有事件。我可以通过单击日历或编辑.jsp中的数组手动添加事件，但我希望它从数据库生成事件。

这是我的代码:

main.jsp

<form name="choose" method="POST">
<table class="centerTable">
<tr>
    <td>Month</td>
    <td>:</td>
    <td>
    <select name="month" style="width:130px" required>
    <option value="">Select a month:</option>
    <option value="${01}" ${param.month == 01 ? 'selected' : ''}>January</option>
    <option value="${02}" ${param.month == 02 ? 'selected' : ''}>February</option>
    <option value="${03}" ${param.month == 03 ? 'selected' : ''}>March</option>
    <option value="${04}" ${param.month == 04 ? 'selected' : ''}>April</option>
    <option value="${05}" ${param.month == 05 ? 'selected' : ''}>May</option>
    <option value="${06}" ${param.month == 06 ? 'selected' : ''}>June</option>
    <option value="${07}" ${param.month == 07 ? 'selected' : ''}>July</option>
    <option value="${08}" ${param.month == 08 ? 'selected' : ''}>August</option>
    <option value="${09}" ${param.month == 09 ? 'selected' : ''}>September</option>
    <option value="${10}" ${param.month == 10 ? 'selected' : ''}>October</option>
    <option value="${11}" ${param.month == 11 ? 'selected' : ''}>November</option>
    <option value="${12}" ${param.month == 12 ? 'selected' : ''}>December</option>
    </select>
    </td>
</tr>
<tr>
    <td>Year</td>
    <td>:</td>
    <td>
    <select name="year" style="width:130px" required>
    <option value="">Select a year:</option>
    <option value="${2016}" ${param.year == '2016' ? 'selected' : ''}>2016</option>
    <option value="${2015}" ${param.year == '2015' ? 'selected' : ''}>2015</option>
    <option value="${2014}" ${param.year == '2014' ? 'selected' : ''}>2014</option>
    <option value="${2013}" ${param.year == '2013' ? 'selected' : ''}>2013</option>
    <option value="${2012}" ${param.year == '2012' ? 'selected' : ''}>2012</option>
    </select>
    </td>
</tr>
<tr>
    <td colspan=3 align=center>
    <input type="submit" name="submit" value="Submit" onChange="submit();return false;"> 
    </td>
</tr>
</table>
</form>
<script>
var y = "${param.year}";
var m = "${param.month}";
$(document).ready(function() {
    $('#calendar').fullCalendar({
        selectable: true,
        selectHelper: true,
        select: function(start, end) {
        var title = prompt('Event Title:');
        var eventData;
        if (title) {
            eventData = {
                title: title,
                start: start,
                end: end
                };
            $('#calendar').fullCalendar('renderEvent', eventData, true);
            }
            $('#calendar').fullCalendar('unselect');
        },
        editable: true,
        eventLimit: true,
        events: "/Leave/KServlet"
    });
    if (y === "" || m === "")
        $('#calendar').fullCalendar('today');
    else
        $('#calendar').fullCalendar('gotoDate', (y+'-'+m));
});
</script>
<div id="calendar"></div>

KServlet.java

public class KServlet extends HttpServlet
{ 
    Calendar now = Calendar.getInstance();
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
    {
        List l = new ArrayList();
        try {
            Connection con = null;
            con = DriverManager.getConnection("jdbc:derby://localhost:1527/C:''Users''Acer''Desktop''livedb?username=username&password=password");
            int month, year;
            if (request.getParameter("month").equals(""))
                month = now.get(Calendar.MONTH) + 1;
            else
                month = Integer.parseInt(request.getParameter("month"));
            if (request.getParameter("year").equals(""))
                year = now.get(Calendar.YEAR);
            else
                year = Integer.parseInt(request.getParameter("year"));
            Statement stmt = null;
            String query = "select PERSON_NAME, TYPE_CODE, FROM_DATE, TO_DATE " +
                           "from LV_INFO_VIEW " +
                           "where YEAR(FROM_DATE) = " + year + " and MONTH(FROM_DATE) = " + month;
            stmt = con.createStatement();
            ResultSet rs = stmt.executeQuery(query);
            while (rs.next()) {
                CalendarDTO c = new CalendarDTO();
                c.setTitle(rs.getString("PERSON_NAME"));
                c.setStart(rs.getString("FROM_DATE"));
                c.setEnd(rs.getString("TO_DATE"));
                String t = rs.getString("TYPE_CODE");
                if (t.equalsIgnoreCase("ANNUAL") || t.equalsIgnoreCase("AL - CT"))
                {
                    c.setColor("green");
                    c.setTextColor("white");
                }
                else if (t.equalsIgnoreCase("MEDICAL") || t.equalsIgnoreCase("ML-CT"))
                {
                    c.setColor("red");
                    c.setTextColor("white");
                }
                else if (t.equalsIgnoreCase("MARRIAGE"))
                {
                    c.setColor("#ff6699");
                    c.setTextColor("black");
                }
                else if (t.equalsIgnoreCase("MATERNITY") || t.equalsIgnoreCase("PATERNITY"))
                {
                    c.setColor("#b2e7d3");
                    c.setTextColor("black");
                }
                else if (t.equalsIgnoreCase("UNPAID"))
                {
                    c.setColor("blue");
                    c.setTextColor("white");
                }
                else if (t.equalsIgnoreCase("COMPASSIONATE") || t.equalsIgnoreCase("DOF"))
                {
                    c.setColor("black");
                    c.setTextColor("white");
                }
                else if (t.equalsIgnoreCase("REPLACEMENT"))
                {
                    c.setColor("#720045");
                    c.setTextColor("white");
                }
                else if (t.equalsIgnoreCase("HOSPITAL") || t.equalsIgnoreCase("SICK"))
                {
                    c.setColor("#7a0000");
                    c.setTextColor("white");
                }
                else if (t.equalsIgnoreCase("EMERGENCY"))
                {
                    c.setColor("yellow");
                    c.setTextColor("black");
                }
                else
                {
                    c.setColor("#ffd4b1");
                    c.setTextColor("black");
                }
                l.add(c);
            }
        }
        catch (SQLException ex) { Logger.getLogger(KServlet.class.getName()).log(Level.SEVERE, null, ex); }
        response.setContentType("application/json");
        response.setCharacterEncoding("UTF-8");
        PrintWriter out = response.getWriter();
        out.write(new Gson().toJson(l));
    }
}

还有CalendarDTO类。它包含title, start, end, color和textColor。所有变量都是字符串，并有各自的setter &getter。

servlet在web.xml中被正确映射，Netbeans没有输出任何错误。

然而，从Chrome控制台我可以看到，KServlet返回了一个空白页，只有'[]'。我猜我在servlet中搞砸了一些东西，但我不确定是什么。

我真的很感谢任何一个能帮助我的人。