使用 enctype="multipart/form-data" 时，请求 getParameter 始终为空； [英] request getParameter is always null when using enctype="multipart/form-data"

问题描述

我正在对输入的数据(例如电子邮件、密码、姓名等)进行验证.但我已经陷入验证的第一阶段，即检查用户是否未输入任何内容.

I am performing validation of inputted data such as email, password, name, etc. But I am already stuck on the first stage of validation which is to check if User entered nothing.

我已经添加了 enctype="multipart/form-data" 如前所述 这里 但现在它总是将 email 识别为 null 并且我无法在成功的情况下转发到登录页面(当电子邮件不为空时).

I already added enctype="multipart/form-data" as mentioned here but now it is always recognizing email as null and I can't forward to the login page in case of success (when email is not null).

注册.jsp

<form method="POST" action="signup" enctype="multipart/form-data">
    <input type="email" name="email" placeholder="[e-mail]">
    <input type="submit" value="Submit">
</form>

SignUpAction.java

SignUpAction.java

public class SignUpAction implements Action {

@Override
public String handleRequest(HttpServletRequest req, HttpServletResponse resp, DAOFactory dao)
        throws ServletException, IOException {

        String email = req.getParameter("email");

        if (email == null || email.isEmpty()) {
            return "signup";   // It loads signup page again (it works)
        }

        return "login";   // It should go to the login page (it doesn't work)
    }

}

推荐答案

除非您打算使用表单上传文件，否则不需要指定multipart/form-data"的编码类型.

Unless you're planning to use your form for uploading a file, you don't need to specify the encoding type of "multipart/form-data".

<form method="POST" action="signup">
    <input type="text" name="email" placeholder="[e-mail]">
     <input type="submit" value="Submit">
</form>

链接中的最后一段说明:

The last paragraph in your link states:

当使用 enctype="multipart/form-data" 时，所有参数都编码在请求正文中.这意味着 request.getParameter(...) 将为所有发布的参数返回 null."

"When using enctype="multipart/form-data", all parameters are encoded in the request body. That means that request.getParameter(...) will return null for all posted parameters then."

输入类型:电子邮件

电子邮件是一种 html5 输入类型.如何使用新的电子邮件、URL 和电话输入类型.

Email is an html5 input type. How To Use The New Email, URL, and Telephone Input Types.

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