Question

我需要获得下拉列表，单选按钮和复选框的值。我使用request.getParameter()方法，但它返回null值。

JSP代码：

<%@page contentType="text/html" pageEncoding="UTF-8"%>

<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>JSP Page</title>
</head>
<body>
    <form action="trial.jsp"  method="POST" enctype="multipart/form-data">
        <table>
            <tr>
                <td class="entry">
                    Highest Qualification :
                </td>
                <td class="entry">
                    <select name="mon">
                        <option value="01">01</option>
                        <option value="02">02</option>
                        <option value="03">03</option>
                        <option value="04">04</option>
                        <option value="05">05</option>

                    </select>
                    <input type="submit" value="Submit" name="submit" />
                </td>
            </tr>
            <tr>
                <td class="entry">
                    <input type="radio" name="gender" value="Male" />Male
                    <input type="radio" name="gender" value="Female" />Female
                </td>
            </tr>
        </table>
    </form>
   </body>
</html>

Servlet代码：

public class NewServlet extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
        String bdate = null;
        bdate = request.getParameter("mon");
        System.out.print("This is" + bdate);
    }
}

Answer 1

问题是您的<form>有enctype="multipart/form-data"。您只应在尝试上传文件时在<form>中添加该属性。由于在您当前的页面中您不需要上传文件，只需将其删除即可完美运行：

<form action="trial.jsp"  method="POST" >
    <table>
        <tr>
            <td class="entry">
    <!-- rest of your HTML code -->
</form>

如果您希望/需要将文件上传功能添加到当前页面，请参阅How to upload files to server using JSP/Servlet?以解决这些问题（我不会在这个答案中重新发明轮子）。

Answer 2

对于下拉列表：

<form action="sample_servlet" method="post">
  <select name="item">
    <option value="1">1</option>
    <option value="2">2</option>
    <option value="3">3</option>
  </select>
  <input type="submit" value="Submit">
</form>

在您的sample_servlet中，写下此request.getParameter("item");或

if(request.getParameter("item")!=null)
{
   selectedItem=Integer.ParseInt(request.getParameter("item"));
}

对于单选按钮：

在jsp中你的代码可能是

<input type="radio" name="dish" value="Indian"> Indian</input>

页面中的

  String radio = request.getParameter("dish");

如何从jsp获取dropdownlist，单选按钮的值并将其发送到servlet？

2 个答案: