java-3.1/java 3.1 at main · samarth1555/java-3.1 · GitHub

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//Part (a): User Login Using Servlet and HTML Form
//login.html
<!DOCTYPE html>
<html>
<head>
    <title>User Login</title>
</head>
<body>
    <h2>Login Form</h2>
    <form action="LoginServlet" method="post">
        Username: <input type="text" name="username" required><br><br>
        Password: <input type="password" name="password" required><br><br>
        <input type="submit" value="Login">
    </form>
</body>
</html>


//LoginServlet.java
package com.example;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class LoginServlet extends HttpServlet {

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

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

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

        // Hardcoded credentials for simplicity
        if ("admin".equals(username) && "12345".equals(password)) {
            out.println("<h2>Welcome, " + username + "!</h2>");
        } else {
            out.println("<h3 style='color:red;'>Invalid credentials! Please try again.</h3>");
        }
        out.close();
    }
}

//web.xml (Deployment Descriptor)
<web-app xmlns="https://jakarta.ee/xml/ns/jakartaee"
         version="5.0">

    <servlet>
        <servlet-name>LoginServlet</servlet-name>
        <servlet-class>com.example.LoginServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>LoginServlet</servlet-name>
        <url-pattern>/LoginServlet</url-pattern>
    </servlet-mapping>
</web-app>


Part (b): Display Employee Records with JDBC and Servlet

Database Setup
CREATE TABLE Employee (
    EmpID INT PRIMARY KEY,
    Name VARCHAR(50),
    Salary DOUBLE
);

INSERT INTO Employee VALUES (101, 'Alice', 50000), (102, 'Bob', 60000), (103, 'Charlie', 70000);

//search.html
<!DOCTYPE html>
<html>
<head>
    <title>Employee Search</title>
</head>
<body>
    <h2>Search Employee by ID</h2>
    <form action="EmployeeServlet" method="get">
        Enter Employee ID: <input type="text" name="empid">
        <input type="submit" value="Search">
    </form>
    <br>
    <a href="EmployeeServlet">View All Employees</a>
</body>
</html>

//EmployeeServlet.java
package com.example;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;

public class EmployeeServlet extends HttpServlet {

    private static final String URL = "jdbc:mysql://localhost:3306/testdb";
    private static final String USER = "root";
    private static final String PASSWORD = "your_password";

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

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

        String empIdParam = request.getParameter("empid");

        try (Connection con = DriverManager.getConnection(URL, USER, PASSWORD)) {
            Statement st = con.createStatement();

            String query = (empIdParam != null && !empIdParam.isEmpty())
                    ? "SELECT * FROM Employee WHERE EmpID=" + empIdParam
                    : "SELECT * FROM Employee";

            ResultSet rs = st.executeQuery(query);

            out.println("<html><body>");
            out.println("<h2>Employee Details</h2>");
            out.println("<table border='1'><tr><th>EmpID</th><th>Name</th><th>Salary</th></tr>");

            boolean found = false;
            while (rs.next()) {
                found = true;
                out.println("<tr><td>" + rs.getInt("EmpID") + "</td><td>"
                        + rs.getString("Name") + "</td><td>"
                        + rs.getDouble("Salary") + "</td></tr>");
            }

            if (!found) out.println("<tr><td colspan='3'>No records found!</td></tr>");
            out.println("</table>");
            out.println("</body></html>");

        } catch (SQLException e) {
            out.println("<p style='color:red;'>Database error: " + e.getMessage() + "</p>");
        }
    }
}
//web.xml
<web-app xmlns="https://jakarta.ee/xml/ns/jakartaee" version="5.0">

    <servlet>
        <servlet-name>EmployeeServlet</servlet-name>
        <servlet-class>com.example.EmployeeServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>EmployeeServlet</servlet-name>
        <url-pattern>/EmployeeServlet</url-pattern>
    </servlet-mapping>
</web-app>


//Part (c): Student Attendance Portal Using JSP and Servlet
//Database Setup

CREATE TABLE Attendance (
    StudentID INT,
    Date DATE,
    Status VARCHAR(10)
);
//attendance.jsp
<%@ page contentType="text/html;charset=UTF-8" %>
<!DOCTYPE html>
<html>
<head>
    <title>Student Attendance</title>
</head>
<body>
    <h2>Mark Attendance</h2>
    <form action="AttendanceServlet" method="post">
        Student ID: <input type="text" name="studentId" required><br><br>
        Date: <input type="date" name="date" required><br><br>
        Status:
        <select name="status">
            <option value="Present">Present</option>
            <option value="Absent">Absent</option>
        </select><br><br>
        <input type="submit" value="Submit">
    </form>
</body>
</html>

//AttendanceServlet.java
package com.example;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;

public class AttendanceServlet extends HttpServlet {

    private static final String URL = "jdbc:mysql://localhost:3306/testdb";
    private static final String USER = "root";
    private static final String PASSWORD = "your_password";

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

        String studentId = request.getParameter("studentId");
        String date = request.getParameter("date");
        String status = request.getParameter("status");

        try (Connection con = DriverManager.getConnection(URL, USER, PASSWORD)) {
            String sql = "INSERT INTO Attendance (StudentID, Date, Status) VALUES (?, ?, ?)";
            PreparedStatement ps = con.prepareStatement(sql);
            ps.setInt(1, Integer.parseInt(studentId));
            ps.setDate(2, Date.valueOf(date));
            ps.setString(3, status);

            int rows = ps.executeUpdate();

            if (rows > 0) {
                RequestDispatcher rd = request.getRequestDispatcher("success.jsp");
                rd.forward(request, response);
            } else {
                response.getWriter().println("<h3>Failed to record attendance.</h3>");
            }

        } catch (SQLException e) {
            response.getWriter().println("<h3>Database Error: " + e.getMessage() + "</h3>");
        }
    }
}

//success.jsp
<%@ page contentType="text/html;charset=UTF-8" %>
<!DOCTYPE html>
<html>
<head><title>Success</title></head>
<body>
    <h2>Attendance recorded successfully!</h2>
    <a href="attendance.jsp">Mark another</a>
</body>
</html>