java - 如何在不使用javascript的情况下在html页面中显示密码错误错误

Question

我想在html页面中显示密码错误错误，我可以使用requestdispatcher在不同的页面中执行此操作，但如何仅使用java和html在同一登录页面中显示它，我对javascript一无所知，谢谢

HTML 代码:

<p>Sign into your account</p>
<form action="bs" align="center" method="POST" onSubmit="return 
validateLogin()">
<input type="text" name="u_name" placeholder="Username"><br>
<input type="password" name="pswd2" placeholder="Password"><br>
<br>
<input type="submit" value="Login!" >
<span style="color:red;">${errMsg)</span>
</form>

Servlet 代码:

 if(rs.next())
    {
        ResultSet rs1=stmt.executeQuery(vsql1);

        if(rs1.next())
        {
            out.println("----Welcome----");
        }
        else
        {
             request.setAttribute("errMsg", "Invalid username or password"); 
              RequestDispatcher dispatcher = request.getRequestDispatcher("login.html");
              dispatcher.forward( request, response);
        }
    }
    else
    {
        request.setAttribute("errMsg", "Invalid username or password"); 
              RequestDispatcher dispatcher = request.getRequestDispatcher("login.html");
              dispatcher.forward( request, response);
    }

    }

Answer 1

PrintWriter out=new PrintWriter();out.println("密码不匹配);

它将在浏览器中显示该值