Programming Pandit: Adv JAVA

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Thursday, February 22, 2024

Adv JAVA February 22, 2024

Code for CONCEPT of RMI

Hello.java

Code :

import java.rmi.Remote;

import java.rmi.RemoteException;

// Remote interface

public interface Hello extends Remote {

// Remote method declaration

String sayHello() throws RemoteException;

}

HelloImpl.java

Code:

import java.rmi.RemoteException;

import java.rmi.server.UnicastRemoteObject;

// Remote object implementation

public class HelloImpl extends UnicastRemoteObject implements Hello {

// Constructor (needed to throw RemoteException)

public HelloImpl() throws RemoteException {

super();

}

// Implementation of the remote method

public String sayHello() throws RemoteException {

return "Hello, Remote World!";

}

HelloServer.java

Code:

import java.rmi.registry.LocateRegistry;

import java.rmi.registry.Registry;

public class HelloServer {

public static void main(String[] args) {

try {

// Create and export a remote object instance

HelloImpl helloObj = new HelloImpl();

// Get RMI registry on port 1099 (default)

Registry registry = LocateRegistry.createRegistry(6677ja);

// Bind the remote object's stub in the registry

registry.rebind("HelloService", helloObj);

System.out.println("Server is ready...");

} catch (Exception e) {

System.err.println("Server exception: " + e.toString());

e.printStackTrace();

}

HelloClient.java

Code:

import java.rmi.registry.LocateRegistry;

import java.rmi.registry.Registry;

public class HelloClient {

public static void main(String[] args) {

try {

// Get RMI registry on localhost, port 1099

Registry registry = LocateRegistry.getRegistry("localhost", 6677);

// Look up the remote object by the name

Hello helloObj = (Hello) registry.lookup("HelloService");

// Invoke the remote method

String response = helloObj.sayHello();

System.out.println("Response from Server: " + response);

} catch (Exception e) {

System.err.println("Client exception: " + e.toString());

e.printStackTrace();

}

Note: For it You have to Start the RMI registry (in a separate terminal or command prompt) using command :

start rmiregistry

Output:

Dr. Gopal Krishna 0

Adv JAVA February 22, 2024

Code for CONCEPT of BEAN

Person.java

Code:

public class Person {

private String name;

private int age;

public Person() {

this.name = "Unknown";

this.age = 0;

}

public String getName() {jav

return name;

}

public void setName(String name) {

this.name = name;

}

public int getAge() {

return age;

}

public void setAge(int age) {

this.age = age;

}

public void displayInfo() {

System.out.println("Name: " + name);

System.out.println("Age: " + age);

}

Main.java

Code:

public class Main {

public static void main(String[] args) {

// Create a new Person object

Person person = new Person();

// Set properties using setter methods

person.setName("John Doe");

person.setAge(30);

// Get and display the properties using getter methods

System.out.println("Person's Name: " + person.getName());

System.out.println("Person's Age: " + person.getAge());

// Use custom method to display all info

person.displayInfo();

}

Output:

Dr. Gopal Krishna 0

Adv JAVA February 22, 2024

Code for INSERTION of DATA into TABLE using JSP.

Ins.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Insert Data</title>
</head>
<body>
    <h2>Insert Data</h2>
    <form action="insert.jsp" method="post">
        <label for="username">User Name:</label>
        <input type="text" id="name" name="username" required><br><br>
        
        <label for="pass">Password:</label>
        <input type="text" id="pass" name="password" required><br><br>
        
        <input type="submit" value="Insert Data">
    </form>
</body>
</html>

Insert.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ page import="java.sql.*" %>
<%@ page import="java.io.*" %>
<%
    String un  = request.getParameter("username");
    String  pass = request.getParameter("password");
    
    try {
        Class.forName("com.mysql.jdbc.Driver");
        Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/gk", "root", "");  
        
        // SQL query to insert data into the table
        String query = "INSERT INTO login (un, pass) VALUES (?, ?)";
        PreparedStatement pstmt = con.prepareStatement(query);
        pstmt.setString(1, un);
        pstmt.setString(2, pass);
        
        int rowsAffected = pstmt.executeUpdate();
        
        if (rowsAffected > 0) {
            // Insertion successful
            out.println("Data inserted successfully");
        } else {
            // Insertion failed
            out.println("Failed to insert data");
        }
        
        con.close();
    }
    catch (Exception e) {
        out.println("Error: " + e);
    }
%>



Output:

Dr. Gopal Krishna 0

Adv JAVA February 22, 2024

Code for User Validation using JSP

index.html


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Login</title>
</head>
<body>
    <h2>Login</h2>
    <form action="login.jsp" method="post">
        <label for="username">Username:</label>
        <input type="text" id="username" name="username" required><br><br>
        
        <label for="password">Password:</label>
        <input type="password" id="password" name="password" required><br><br>
        
        <input type="submit" value="Login">
    </form>
</body>
</html>



login.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ page import="java.sql.*" %>
<%@ page import="java.io.*" %>
<%
    String un = request.getParameter("username");
    String pass = request.getParameter("password");   
    try {
        Class.forName("com.mysql.jdbc.Driver");
        Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/gk", "root", "");  
        // SQL query to validate user
        String query = "SELECT * FROM login WHERE un=? AND pass=?";
        PreparedStatement pstmt = con.prepareStatement(query);
        pstmt.setString(1, un);
        pstmt.setString(2, pass);        
        ResultSet rs = pstmt.executeQuery();
        if (rs.next())
        {
            // Valid user
            out.println("Welcome " + un);
        } else {
            // Invalid user
            out.println("Invalid username or password");
        }   
        con.close();
    }
    catch (Exception e) {
        out.println("Error: " + e);
    }
%>


Output:

Dr. Gopal Krishna 0

Adv JAVA February 22, 2024

Code for one SERVLET call the another SERVLET by G Krishna

FirstServlet.java

import jakarta.servlet.ServletException;

import jakarta.servlet.annotation.WebServlet;

import jakarta.servlet.http.HttpServlet;

import jakarta.servlet.http.HttpServletRequest;

import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;

@WebServlet("/FirstServlet")

public class FirstServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

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

System.out.println("GK Testing of Runing this code");

// Redirecting to another servlet page

String servletUrl = request.getContextPath() + "/SecondServlet"; // URL of the servlet to redirect to

response.sendRedirect(servletUrl);

}

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

doGet(request, response);

}

SecondServlet.java

import jakarta.servlet.ServletException;

import jakarta.servlet.annotation.WebServlet;

import jakarta.servlet.http.HttpServlet;

import jakarta.servlet.http.HttpServletRequest;

import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;

import java.io.PrintWriter;

@WebServlet("/SecondServlet")

public class SecondServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

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

response.setContentType("text/html");

// Get the PrintWriter object from HttpServletResponse

PrintWriter out = response.getWriter();

// Print output to the response stream

out.println("<html>");

out.println("<head><title>MyServlet Output</title></head>");

out.println("<body>");

out.println("<h1>Hello, Students!</h1>");

out.println("<p>This is a servlet example.</p>");

out.println("</body>");

out.println("</html>");

// Close the PrintWriter

out.close();

}

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

doGet(request, response);

}

Dr. Gopal Krishna 0

Wednesday, February 21, 2024

Adv JAVA February 21, 2024

SERVLET PROGRAM FOR CALLING ONE SERVLET BY ANOTHER by G Krishna

Comming Soon. ..

Dr. Gopal Krishna 0

Adv JAVA February 21, 2024

SESSION TRACKING IN SERVLET by G Krishna

SessionSetupServlet.java:

import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;
import java.io.IOException;

@WebServlet("/SessionSetupServlet")
public class SessionSetupServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Create a new session or get the existing session
        HttpSession session = request.getSession();

        // Set session attributes
        session.setAttribute("username", "G Krishna");
        session.setAttribute("email", "cse.gopalkrishna@gmail.com");

        response.getWriter().println("Session has been set up.");
    }
}


SessionDisplayServlet.java

import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;
import java.io.IOException;

@WebServlet("/SessionDisplayServlet")
public class SessionDisplayServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Get the session
        HttpSession session = request.getSession();

        // Get session attributes
        String username = (String) session.getAttribute("username");
        String email = (String) session.getAttribute("email");

        response.setContentType("text/html");
        response.getWriter().println("Session Attributes:<br>");
        response.getWriter().println("Username: " + username + "<br>");
        response.getWriter().println("Email: " + email + "<br>");
    }
}


SessionRemoveServlet.java


import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;
import java.io.IOException;

@WebServlet("/SessionRemoveServlet")
public class SessionRemoveServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Get the session
        HttpSession session = request.getSession();

        // Remove session attributes
        session.removeAttribute("username");
        session.removeAttribute("email");

        // Invalidate the session
        session.invalidate();

        response.getWriter().println("Session attributes have been removed and session has been invalidated.");
    }
}



Web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="https://jakarta.ee/xml/ns/jakartaee" xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd" id="WebApp_ID" version="6.0">
  <display-name>se</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.jsp</welcome-file>
    <welcome-file>default.htm</welcome-file>
  </welcome-file-list>
  <servlet>
    <description></description>
    <display-name>SessionSetupServlet</display-name>
    <servlet-name>SessionSetupServlet</servlet-name>
    <servlet-class>SessionSetupServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>SessionSetupServlet</servlet-name>
    <url-pattern>/SessionSetupServlet</url-pattern>
  </servlet-mapping>
  <servlet>
    <description></description>
    <display-name>SessionDisplayServlet</display-name>
    <servlet-name>SessionDisplayServlet</servlet-name>
    <servlet-class>SessionDisplayServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>SessionDisplayServlet</servlet-name>
    <url-pattern>/SessionDisplayServlet</url-pattern>
  </servlet-mapping>
  <servlet>
    <description></description>
    <display-name>SessionRemoveServlet</display-name>
    <servlet-name>SessionRemoveServlet</servlet-name>
    <servlet-class>SessionRemoveServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>SessionRemoveServlet</servlet-name>
    <url-pattern>/SessionRemoveServlet</url-pattern>
  </servlet-mapping>
</web-app>


Output: 

Dr. Gopal Krishna 0

Adv JAVA February 21, 2024

Servlet code for use of Cookies by G Krishna

Dear Students,

This is the code for working of the Cookies using the Servlet.

CookieServlet.java

import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.Cookie;
import java.io.IOException;

@WebServlet("/CookieSetupServlet")
public class CookieServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public void doGet(HttpServletRequest request, HttpServletResponse response) 
    throws ServletException, IOException {
        // Creating a new cookie
        Cookie cookie = new Cookie("username", "G Krishna");

        // Setting cookie path
        cookie.setPath("/");

        // Setting cookie expiration time - 24 hours (in seconds)
        cookie.setMaxAge(24 * 60 * 60);

        // Adding the cookie to the response
        response.addCookie(cookie);

        response.getWriter().println("Cookie has been set.");
    }

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


CookieDisplayServlet.java

import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.Cookie; // Import Cookie from jakarta.servlet.http
import java.io.IOException;

@WebServlet("/CookieDisplayServlet")
public class CookieDisplayServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) 
    throws ServletException, IOException {
        // Retrieving cookies from the request
        Cookie[] cookies = request.getCookies(); // Use Cookie directly without package name
        
        response.setContentType("text/html");
        
        if (cookies != null) {
            for (Cookie cookie : cookies) { // Use Cookie directly without package name
                if (cookie.getName().equals("username")) {
                    response.getWriter().println("Cookie Name: " + cookie.getName() + "<br>");
                    response.getWriter().println("Cookie Value: " + cookie.getValue() + "<br>");
                    
                    // Deleting the cookie
                    cookie.setMaxAge(0);
                    cookie.setPath("/"); // Set to root path
                    response.addCookie(cookie);
                    
                    response.getWriter().println("Cookie has been deleted.");
                    return;
                }
            }
        }
        
        response.getWriter().println("Cookie not found.");
    }

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


Web.xml:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="https://jakarta.ee/xml/ns/jakartaee"
    xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd"
    id="WebApp_ID" version="6.0">
    
  <display-name>co</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.jsp</welcome-file>
    <welcome-file>default.htm</welcome-file>
  </welcome-file-list>
  
    <description></description>
  <servlet>
    <description></description>
    <display-name>CookieServlet</display-name>
    <servlet-name>CookieServlet</servlet-name>
    <servlet-class>CookieServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>CookieServlet</servlet-name>
    <url-pattern>/CookieServlet</url-pattern>
  </servlet-mapping>
  <servlet>
  
  
    <description></description>
    <display-name>CookieDisplayServlet</display-name>
    <servlet-name>CookieDisplayServlet</servlet-name>
    <servlet-class>CookieDisplayServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>CookieDisplayServlet</servlet-name>
    <url-pattern>/CookieDisplayServlet</url-pattern>
  </servlet-mapping>
</web-app>





Output:

Dr. Gopal Krishna 0

Tuesday, February 20, 2024

Adv JAVA February 20, 2024

How to start a new Servlet project in eclipse by G Krishna

Dear Students,

For the startup of the Servlet project follow the following steps.

Now Add servlet-api.jar JAR file to your project. Click on Libraries then right click on Web App Libraries then select Build Path -> Configure Build Path