K_U*_*K_U 2 database jsp jstl drop-down-menu
我知道以前曾经问过这个问题,但这对我不起作用.
我正在尝试使用jstl从数据库填充下拉列表,这是我用作usebean的类:
public class feedData {
Connection con;
public feedData() throws ClassNotFoundException, InstantiationException, IllegalAccessException, SQLException {
Class.forName("com.mysql.jdbc.Driver").newInstance();
String url = "******";
con = DriverManager.getConnection(url, "**", "**");
}
public ArrayList<String> getUnis() throws SQLException {
ArrayList<String> uniList = new ArrayList<String>();
String tryquery = "select aff from libra.smalluniqdbtmp";
Statement stmt2 = con.createStatement();
ResultSet rs1 = stmt2.executeQuery(tryquery);
while (rs1.next()) {
uniList.add(rs1.getString("aff"));
}
return uniList;
}
public ArrayList<String> getRI() throws SQLException {
ArrayList<String> RIList = new ArrayList<String>();
String tryquery = "select interest from libra.riuniqdb";
Statement stmt2 = con.createStatement();
ResultSet rs1 = stmt2.executeQuery(tryquery);
while (rs1.next()) {
RIList.add(rs1.getString("aff"));
}
return RIList;
}
}
这是我的jsp:
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
</head>
<body>
<jsp:useBean id="obj" scope="page" class="uiLibraWeb2Pkg.feedData" />
<h1>Hello World!</h1>
<table border="1">
<thead>
<tr>
<th></th>
<th></th>
<th></th>
<th></th>
</tr>
</thead>
<tbody>
<tr>
<td> <form action="response.jsp">
<strong>Select a university:</strong>
<select name="affiliation">
<c:forEach var="aff" items="${obj.unis}">
<option value="${aff}"></option>
</c:forEach>
</select>
</form>
</td>
<td></td>
<td></td>
<td></td>
</tr>
<tr>
<td></td>
<td></td>
<td></td>
<td></td>
</tr>
</tbody>
</table>
</body>
</html>
服务器日志和项目的构建输出中没有错误消息,但下拉列表为空.一直在努力,我不知道什么是错的.我还尝试设置数据源,并使用jstl迭代查询的结果集来执行此操作,但行为方式相同.
现在我不依赖于任何数据源,但结果仍然相同.
帮助表示感谢,谢谢
我没有测试过你的代码,但是请在服务器端添加一个断点来检查列表中有多少元素.也许它在服务器端也是空的.
第二点是这段代码
<option value="${aff}"></option>
不向用户显示任何内容,因为它在HTML中呈现为没有文本的选项.也许它应该是
<option value="${aff}">${aff}</option>