Question

我必须通过从Database.Am获取值来动态加载下拉列表，使用Servlet作为Controller将Array列表传递给jsp页面。在jsp页面中，使用jstl显示数组列表，但未显示值。任何帮助将不胜感激。

DAO：

//Method call to retrieve the customer names from Database        
public List<Report> getAllCustomers() {

    List<Report> customers = new ArrayList<Report>();

    Connection conn = null;

    Statement stmt = null;

    ResultSet rs = null;

    try {



        prop = PropertyFileLoaderTon.getInstance()
                .getPropertiesConfiguration(REPORTDATA_PROPERTY_FILE);

        String tableName = prop.getString(REPORTS_TABLE);

        String sql = "select  distinct CUSTOMERNAME from tableName ";


        conn = ConnectionFactory.getInstance().getConnection();


        stmt = conn.createStatement();

        rs = stmt.executeQuery(sql);

        while (rs.next()) {
            Report report = new Report();

            String customer = rs.getString("CUSTOMERNAME");

            report.setCustomerName(customer);


            customers.add(report);

        }

    } catch (Exception e) {

        e.printStackTrace();
    } finally {

        try {
            if (stmt != null) {
                stmt.close();
                stmt = null;
            }
            if (conn != null) {
                conn.close();
                conn = null;
            }
        } catch (Exception e) {
        }

    }
    return customers;
}

Servlet：

protected void doPost(HttpServletRequest request,
        HttpServletResponse response) throws ServletException, IOException {

    GenericDao genericDao = new GenericDao();

    List<Report> customers = genericDao.getAllCustomers();

    request.setAttribute("CustomerList", customers);

    request.getRequestDispatcher("jsp/ShowReport.jsp").forward(request,
            response);

}

JSP：

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
     pageEncoding="ISO-8859-1"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>


<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
        <title>Insert title here</title>
    </head>
    <body>
    <form action="/ReportData/DisplayReport" method="post">

        Please select an element: 


        <select id="selectedRecord" name="selectedRecord">

            <c:forEach var="CustomerList" items="${CustomerList}">

                <option value="${CustomerList}">${CustomerList.customerName}</option>

            </c:forEach>

        </select>

        <input type="submit" value="Submit" align="middle"> 

    </form>

</body>
</html>

豆：

公共课报告{

private String customerName;

public String getCustomerName() {
    return customerName;
}

public void setCustomerName(String customerName) {
    this.customerName = customerName;
}

}

Answer 1

代码似乎正确...尝试将var="CustomerList"更改为其他名称......

当您在${CustomerList.customerName}

下访问时，同名的问题可能会造成混淆

尝试var =“customers”

然后${customers.customerName}

Answer 2

我认为这主要是因为以下原因：

＆lt;“option value =”$ {CustomerList}“＆gt; $ {CustomerList.customerName}＆lt;”/“选项＆gt;

您可能想要设置

＆lt;“option value =”$ {CustomerList.customerID}“＆gt; $ {CustomerList.customerName}＆lt;”/ option＆gt;

假设这是您想要的，或者只是customerName再次

Answer 3

在GET映射（而不是POST）上设置它并显示

编辑：

（在您的servlet上），doGET方法应该拥有它，然后将在您的站点上，然后使用post方法可以恢复值。

使用jstl动态加载下拉列表

3 个答案: