Step 1: Create the HTML Login Form
Create an HTML file named login.html. This file contains a form where users can enter their username and password.
<html>
<head>
<title>Login Form</title>
</head>
<body>
<h2>Login Form</h2>
<form action="login" method="post">
<label for="username">Username:</label>
<input type="text" id="username" name="username"><br><br>
<label for="password">Password:</label>
<input type="password" id="password" name="password"><br><br>
<input type="submit" value="Login">
</form>
</body>
</html>Step 2: Create the Servlet to Handle Login Data
Now, create a new Java class named LoginServlet.java. This servlet will handle the form submission and retrieve the data.
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/login")
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// Retrieve data from the login form
String username = request.getParameter("username");
String password = request.getParameter("password");
// For demonstration purposes, print the username and password
response.setContentType("text/html");
response.getWriter().println("<h1>Login Successful</h1>");
response.getWriter().println("<p>Username: " + username + "</p>");
response.getWriter().println("<p>Password: " + password + "</p>");
}
}
Step-by-Step Explanation
- HTML Form:
- The
<form>tag has anactionattribute set tologinand amethodattribute set topost. This means that when the form is submitted, it will send a POST request to theloginURL. - The form contains two input fields: one for the username and one for the password, and a submit button.
- The
- LoginServlet:
- @WebServlet(“/login”): This annotation maps the servlet to the
/loginURL. When the form is submitted, this servlet will handle the request. - doPost Method: This method handles POST requests. It retrieves the username and password from the request using
request.getParameter(). - Response: The servlet sets the response content type to
text/htmland sends back an HTML response displaying the entered username and password.
- @WebServlet(“/login”): This annotation maps the servlet to the
Step 3: Deploy Your Application
- Place
login.htmlin the web directory (e.g.,webapps/your_project_nameif using Tomcat). - Compile and deploy
LoginServlet.javaas part of your web application. - Start your server (Tomcat) and navigate to
http://localhost:8080/your_project_name/login.htmlin your web browser.
When you fill out the form and click the login button, the servlet will handle the request, retrieve the data, and display it back to you.