1

在基于下拉选择获取查询结果时遇到问题，由于某种原因，它在尝试将其发布到 jsp 时没有返回任何内容。

这是我的代码的样子

这是我的 index.jsp

<form method="post" action="Test">
    <h3>Get today's feed event</h3>
    <p>
        <select name="colour" size="1" class="selectpicker" data-style="btn-inverse">
            <option value="light">Runningball</option>
            <option value="amber">Enetpulse</option>
            <option value="DonBest">DonBest</option>
            <option value="BetRadar">Betradar</option>

        </select>
        </p>
         <input type="submit" value="Submit" class="btn">
</form>

这是我的逻辑

public List<String> getColours(String colour) {


    List<String> colours = new ArrayList<String>();
     if(colour.equals("DonBest")){


        try {
            connectToCoral3();
            CachedRowSet res1 = con.selectQuery(
                    "select id,name,event_time from nodes where syst_id=16 and event_time>=now() order by event_time");

            //some debugging code
            while (res1.next()) {
                System.out.println("id= " + res1.getString("id") + " name= "
                        + res1.getString("name"));
            }

            while (res1.next()) {
                colours.add(res1.getString("id"));
                colours.add(res1.getString("name"));
                colours.add(res1.getString("event_time"));

        }
        } catch (Exception e) {
            System.out.println(e.getStackTrace());
            e.getStackTrace();
        }
     }else if(colour.equals("light")){
        colours.add("orange");
        colours.add("pink");
    }


    return (colours);
}

小服务程序

public void doPost(HttpServletRequest request, HttpServletResponse response)
        throws IOException, ServletException {
    try {
        String c = request.getParameter("colour");
        ColourExpert ce = new ColourExpert();
        List<String> styles = ce.getColours(c);

    request.setAttribute("styles",styles);
    System.out.println(styles);
    } catch (Exception e) {
        request.setAttribute("error", "Retrieving rows failed.");
        e.printStackTrace();
    }


    RequestDispatcher view = request.getRequestDispatcher("WEB-INF/Home/simplePage.jsp");
    view.forward(request, response);

这是我的jsp，

<c:forEach items="${styles}" var="styles">
        <c:out value="${styles.id}" />
        <c:out value="${styles.name}" />
        <c:out value="${styles.event_time}" />
    </c:forEach>
    <c:if test="${not empty error}">Error: ${error}</c:if>

任何帮助都会很棒

4

2 回答 2

2

删除while代码中的第一个循环。然后它将起作用。

//Remove This
while (res1.next()) {
    System.out.println("id= " + res1.getString("id") + " name= " + res1.getString("name"));
}
于 2013-05-24T10:30:27.073 回答
1

首先要访问 JSTL 中的请求变量，您需要将代码更改为：

<c:forEach items="${requestScope.styles}" var="styles">
    <c:out value="${styles.id}" />
    <c:out value="${styles.name}" />
    <c:out value="${styles.event_time}" />
</c:forEach>
<c:if test="${not empty error}">Error: ${error}</c:if>
于 2013-05-24T10:35:22.040 回答