我需要帮助将arraylist从servlet传递到jsp页面。我正在尝试从Database填充下拉值。我已成功连接到数据库，并且值存储在列表中。该列表将传递给servlet。在servlet中，我通过打印在控制台中检索到的值进行检查。它也很好用。此外，我将属性设置为列表，并使用请求调度程序转发到我的jsp页面。在我的jsp页面中，我正在尝试使用jstl获取值。我还添加了jstl jar并在jsp页面的顶部添加了jstl标记。我已经多次搜索jstl语法，并在我的jsp中实现了它。但是在我的下拉列表中仍然没有检索到值。 在此先感谢。请有人帮助我。
------Success.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%-- <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> --%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%-- <%@ page import = "pack.DtoForm" %>
<jsp:useBean id="dform" scope="page" class="pack.DtoForm" />
<jsp:useBean id="Countries" class="pack.ViewValuesInDB" scope="page"/>
<%@ page import="java.util.*" %> --%>
<!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=ISO-8859-1">
<title>Success page</title>
</head>
<body>
<h1>Success page</h1>
<div class="dbstyle">
<h4>Let's start learning connecting to the database!</h4>
<br>
<!-- <form action="DAOServlet" method="get" name="Countries"> -->
<label >Countries*:</label>
<select id="Countries" name="Countries" >
<c:forEach items="${list}" var="listt">
<option value="${listt.Countries}">${listt}</option>
</c:forEach>
</select>
</div>
<!-- </form> -->
</div>
<div>
</div>
</body>
</html></pre>
DtoForm----------------------
package pack;
public class DtoForm {
private String Countries;
public String getCountries() {
return Countries;
}
public void setCountries(String countries) {
this.Countries= countries;
}
}
ViewValuesInDB----------------------------
package pack;
import java.sql.*;
import java.util.ArrayList;
import com.sybase.jdbcx.*;
public class ViewValuesInDB {
Connection con = null;
Statement stmt = null;
SybDriver sybDriver = null;
DtoForm dform=new DtoForm();
//List<DtoForm>dform =new ArrayList<DtoForm>();
ArrayList<String> list=new ArrayList<String>();
public ArrayList<String> makeConnection() throws Exception {
try
{
sybDriver = (SybDriver) Class.forName(
"com.sybase.jdbc2.jdbc.SybDriver").newInstance();
System.out.println("Driver loaded");
con = DriverManager.getConnection(
"jdbc:sybase:Tds:ip:port","username", "password");
System.out.println("Database connected");
Statement stmt = con.createStatement();
String query = "select Countries from Country";
ResultSet rs = stmt.executeQuery(query);
while (rs.next()) {
String a=rs.getString(1);
dform.setCountries(a.toString());
list.add(dform.getCountries());
}
for(int i=0;i<list.size();i++)
{
System.out.println(list.get(i));
}
rs.close();
stmt.close();
con.close();
}
catch(Exception e)
{
System.out.println("Error is "+e.getMessage());
}
return list;
}
public static void main(String args[]) throws Exception {
System.out.println("inside DB main function");
ViewValuesInDB sc = new ViewValuesInDB();
sc.makeConnection();
}
}
---------------genrated html---------
<!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=ISO-8859-1">
<title>Success page</title>
<style>
.dbstyle
{
width:100%;
height:540px;
background-color:#FDF5E6;
}
</style>
</head>
<body>
<h1>Success page</h1>
<div class="dbstyle">
<h4>Let's start learning connecting to the database!</h4>
<br>
<!-- <form action="DAOServlet" method="get" name="Countries"> -->
<label >Countries*:</label>
<div>
<select id="Countries" name="Countries" >
</select>
</div>
<!-- </form> -->
</div>
<div>
</div>
</body>
</html>
-------servlet modified--------
package pack;
import java.util.ArrayList;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class DropdownServlet extends HttpServlet {
/**
*
*/
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request,
HttpServletResponse response) {
System.out.println("action is called inside dropdown");
ViewValuesInDB daoobj = new ViewValuesInDB();
ArrayList<String> list;
try {
list = daoobj.makeConnection();
System.out.println(list);
if(null == list)
{System.out.println("list is null");
}
else{
System.out.println("list has values");
}
request.setAttribute("list", list);
request.getRequestDispatcher("Success.jsp").forward(request,response);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static void main(String args[]) throws Exception {
System.out.println("inside servlet function");
DropdownServlet sc = new DropdownServlet();
sc.doGet(null, null);
}
}