request.getAttribute return null from HTML

Question

I wrote a login HTML and submit the username, password to the servlet

@WebServlet(name = "loginServlet")
public class loginServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("post");
        Enumeration enumeration = request.getAttributeNames();
        while (enumeration.hasMoreElements()) {
            System.out.println(enumeration.nextElement());
        }
        String username = (String) request.getAttribute("username");
        String password = (String) request.getAttribute("password");
        System.out.println(username);
        System.out.println(password);
    }

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

    }
}

My HTML:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Login</title>
</head>
<body>

<h1>Login</h1>


<form action="/loginServlet" method="post">
    User Name: <input required name="username" value="name">
    Password: <input required type="password" name="password" value="pw">
    <input type="submit" value="Submit">
</form>

</body>
</html>

The output of the servlet is: post null null

I checked the request.getAttribute returning null in servlet But that situation is JSP, not HTML.

Are there anything wrong? Or can I use the HTML instead of the JSP to get the username and password?

https://stackoverflow.com/questions/5243754/difference-between-getattribute-and-getparameter — Momus, Aug 21 '17 at 04:26

score 1 · Accepted Answer · answered Aug 21 '17 at 04:33

For login page use below code :

<form action="servlet1" method="post"> Name:<input type="text" name="username"/><br/><br/> Password:<input type="password" name="userpass"/><br/><br/> <input type="submit" value="login"/> </form>

and to get attribute of that form create a class and write the below code :

public class FirstServlet extends HttpServlet {  
public void doPost(HttpServletRequest request, HttpServletResponse response)  
    throws ServletException, IOException {  

response.setContentType("text/html");  
PrintWriter out = response.getWriter();  

String n=request.getParameter("username");  
String p=request.getParameter("userpass");  


}  
}

up vote answer if it solves your question. – Braj Ankit Mar 21 '18 at 06:09 — Braj Ankit, Mar 21 '18 at 06:09

score 0 · Answer 2 · answered Aug 21 '17 at 04:28

0

The values "username" and "password" being passed from the form are parameters and not attributes.

Difference between getAttribute() and getParameter()

answered Aug 21 '17 at 04:28

Momus

394
2
13

score 0 · Answer 3 · answered Aug 21 '17 at 04:45

0

Instead of getAttribute use getParameter as in below code ;

String username= request.getParameter("username"); String password= request.getParameter("password");

answered Aug 21 '17 at 04:45

arjun99

358
1
8

score 0 · Answer 4 · answered Aug 21 '17 at 04:54

@HAO, request.getAttribute() is only used in the server side. Use request.getParameter() instead. It is the method we should use to get the value from client side to server side. For more details refer this. Thanks Momus & Braj Ankit

Difference between getAttribute() and getParameter()

request.getAttribute return null from HTML

4 Answers4