Implement Authentication filter using filter API code example

Example 1: Implement Authentication filter using filter API

//Servlet file
import java.io.*;

import javax.servlet.http.HttpServlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ServletFilter extends HttpServlet {
    @Override
    public void doGet(HttpServletRequest res, HttpServletResponse resp) throws IOException, ServletException {
        resp.setContentType("text/html;charset=UTF-8");
        PrintWriter out = resp.getWriter();
        String str = res.getParameter("name");
        out.print("<h1>Hello " + str + "</h1><h2>You have sucessfully logged in....</h2>");

    }

}

Example 2: Implement Authentication filter using filter API

//Java file
import java.io.*;
import javax.servlet.*;

public class MyFilter implements Filter {
    @Override
    public void init(FilterConfig arg0) throws ServletException {
    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain)
            throws IOException, ServletException {
        PrintWriter pw = resp.getWriter();
        String pwd = req.getParameter("password");
        if (pwd.equals("birju")) {
            chain.doFilter(req, resp);
        } else {
            pw.print("Invalid Password");
            RequestDispatcher redi = req.getRequestDispatcher("index.html");
            redi.include(req, resp);
        }
    }

    @Override
    public void destroy() {
    }

}

Example 3: Implement Authentication filter using filter API

<!-- HTML File -->
<html>
<head>
    <title>Filter API</title>
    <style>
        .b1 {
            width: 370px;
            height: 42px;
            margin: 10px;
            color: white;
            background-color: #008CBA;
            border: 0px solid grey;
            cursor: pointer;
        }
        .side {
            padding: 10px;
            margin: 20px;
            width: 370px;
        }
        .b1:hover {
            background-color: #4CAF50;
        }
    </style>
</head>
<body bgcolor="#222222">
    <div class="box">
        <form action="filtering" style="text-align:center;">
            <h1 style="color:white;font-family: Times;margin-top:160px;">Login Portal</h1>
            <input class="side" type="text" required="" name="name" placeholder="UserName"><br>
            <input class="side" type="password" required="" name="password" placeholder="Password" style=margin-top:-5px;">
            <br>
            <input class="b1" type="submit" value="Login">
        </form>
    </div>
</body>
</html>

Example 4: Implement Authentication filter using filter API

<!-- XML File -->
<?xml version="1.0" encoding="UTF-8"?>
<web-app>

    <servlet>
    <servlet-name>ServletFilter</servlet-name>
    <servlet-class>ServletFilter</servlet-class>
    </servlet>
 <welecome-file-list>
          <welcome-file>index.html</welcome-file>
    </welecome-file-list>
  <servlet-mapping>
    <servlet-name>ServletFilter</servlet-name>
    <url-pattern>/filtering</url-pattern>
  </servlet-mapping>
  
 <filter>
  <filter-name>f1</filter-name>
  <filter-class>MyFilter</filter-class>
 </filter>

 <filter-mapping>
  <filter-name>f1</filter-name>
  <url-pattern>/filtering</url-pattern>
 </filter-mapping>
  

</web-app>

Tags:

Java Example

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