Rest API CRUD Project

listing.html
add.html
details.html
edit.html

Product Requirements Document (PRD)

Project: Employee Management CRUD System
Date: July 27, 2025
Author: [Your Name]

1. Purpose & Background

The Employee Management CRUD System aims to provide a simple web-based interface and REST API to manage employee records efficiently. It fulfills the need to maintain essential employee data such as ID, name, department, and salary with complete create, read, update, and delete functionalities.

This product will be used internally by HR staff and managers to maintain an up-to-date employee database with easy access to employee details.

2. Objectives & Goals

  • Enable users to list all employees in a readable tabular format.
  • Allow users to add new employees with required fields (name, department, salary).
  • Support editing employee details with a pre-filled form.
  • Provide a read-only detailed view of individual employees.
  • Allow deletion of employees with user confirmation.
  • REST API endpoints should support all CRUD operations for integration or future enhancements.
  • The UI should be intuitive with responsive, clear action buttons (View, Edit, Delete).

3. Stakeholders

StakeholderRoleResponsibility
Product ManagerOversees requirements & scopeDefine features and priorities
Frontend DeveloperImplements HTML + Axios viewsBuild UI pages and integrate API calls
Backend DeveloperDevelops REST APIImplement API endpoints for employee data
QA TesterQuality assuranceTest functionality and user experience
HR UsersEnd usersUse product to manage employee records

4. User Stories

  • As an HR user, I want to see all employees listed, so that I can find and review employee info quickly.
  • As an HR user, I want to add a new employee, so that I can keep records of newly hired staff.
  • As an HR user, I want to edit employee details, so that I can update information if there are changes.
  • As an HR user, I want to delete an employee, so that I can remove records of former employees.
  • As an HR user, I want to view detailed employee information, so I can get a focused read-only snapshot of an individual’s record.

5. Functional Requirements

IDRequirement DescriptionPriorityNotes
FR-01The system shall display a list of employees with fields: ID, Name, Department, Salary.HighSee listing.html
FR-02The system shall allow adding a new employee with Name, Department, Salary.Highadd.html form submission using Axios
FR-03The system shall allow editing existing employee details via a pre-filled form.Highedit.html with PUT API call
FR-04The system shall allow deletion of an employee with a confirmation popup.HighDelete button triggers confirm popup + Axios DELETE
FR-05The system shall provide a read-only details page to view employee records individually.Mediumdetails.html showing employee details
FR-06The system shall expose the following REST API endpoints: GET /employees, GET /employees/{id}, POST /employees, PUT /employees/{id}, DELETE /employees/{id}.HighBackend API support required

6. Non-functional Requirements

Requirement DescriptionNotes
The system should be responsive and load employee data quickly.Performance: API responses under 2 seconds
Data should be validated on client and server-side.Name and Department non-empty, Salary positive number
System should handle concurrency safely (no data conflicts).Backend-managed
Security: API endpoints to be secured with authentication (future scope).Currently internal use

7. User Interface / UX

  • Tables with borders and clear labeling for readability.
  • Action buttons for View, Edit, Delete placed on each row.
  • Modals or confirm popups for delete actions to prevent accidental deletions.
  • Forms for Add and Edit with required field validation.
  • Navigation links to switch between listing, add, edit, and details pages.

8. API Specification

MethodEndpointDescriptionRequest BodyResponse
GET/api/employeesRetrieve list of all employeesNoneArray of employee objects
GET/api/employees/{id}Retrieve one employee by IDNoneEmployee object
POST/api/employeesCreate a new employeeJSON with name, department, salaryCreated employee object
PUT/api/employees/{id}Update employee by IDJSON with fields to updateUpdated employee object
DELETE/api/employees/{id}Delete employee by IDNoneSuccess status

9. Success Metrics

  • 100% of employee records can be created, viewed, updated, and deleted successfully without errors.
  • User confirmation for delete reduces unintended deletions by 90%.
  • UI loads employee listings and details pages within 2 seconds for up to 1000 records.
  • Positive user feedback from HR team on usability (survey post-release).

10. Timeline & Milestones

MilestoneTarget DateNotes
PRD Approval[Date]Finalize product requirements document.
Design & UI Mockups+1 weekDesign review for all pages.
Backend API Development+3 weeksREST API endpoints complete.
Frontend Development+4 weeksIntegrate UI with API and build views.
QA Testing+5 weeksFunctional and usability testing.
Deployment+6 weeksRelease to production environment.

11. Constraints & Assumptions

  • Current version targets internal HR users only.
  • Authentication & authorization to be added later.
  • Backend API under development or assumed ready to accept calls as described.
  • UI will be web-based, supported in modern browsers.

12. Appendix

  • Sample UI HTML files: listing.html, add.html, edit.html, details.html
  • Axios usage examples for API communication.
  • API specification document (Swagger/OpenAPI recommended for future).

Java Stream Api

import java.util.*;

class StreamApiExample {
    public static void main(String[] args) {

        List<Integer> nums = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5));
        System.out.println(nums);

        List<Integer> arr_nums = nums.stream().map(x -> x * x).toList();
        System.out.println(arr_nums);


        //With Multithreading - this will split and run in parallel cores
        List<Integer> cube_nums = nums.parallelStream().map(x -> x * x * x).toList();
        System.out.println(cube_nums);


        List<Integer> even_nums = nums.stream().filter(x -> x % 2 == 0).toList();
        System.out.println(even_nums);


        int sum_of_nums = nums.stream().reduce((t, x) -> t + x).orElse(0);
        System.out.println(sum_of_nums);

    }
}

Spring Boot

CalcController.java

package com.javatest.demo;

import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

class MyCalc {
    private int num1;
    private int num2;

    public int getNum1() {
        return num1;
    }
    public void setNum1(int num1) {
        this.num1 = num1;
    }
    public int getNum2() {
        return num2;
    }
    public void setNum2(int num2) {
        this.num2 = num2;
    }
    
    @Override
    public String toString() {
        return "MyCalc [num1=" + num1 + ", num2=" + num2 + "]";
    }
}

@RestController
public class CalcController {


    @RequestMapping("test")
    public String test() {
        return "Testing....";
    }

    /** Read query params */
    @RequestMapping("mycalc")
    @GetMapping
    public String getMet(@RequestParam("num1") int x, @RequestParam int y) {
        return String.format("%s + %s = %s", x, y, x+y);
    }

    /** Read raw json data */
    @PostMapping("mycalc")
    public String postMet(@RequestBody MyCalc obj) {
        int x = obj.getNum1();
        int y = obj.getNum2();

        return String.format("%s - %s = %s", x, y, x - y);
    }

    /** Read form data */
    @PutMapping("mycalc")
    public String putMet(
        @RequestParam("num1") int x,
        @RequestParam("num2") int y) {
        return String.format("%s * %s = %s", x, y, x * y);
    }

    /** Read from raw json */
    @DeleteMapping("mycalc")
    public String deleteMet(@RequestBody MyCalc obj) {
        int x = obj.getNum1();
        int y = obj.getNum2();
        return String.format("%s / %s = %s", x, y, x / y);
    }

}

src/main/resources/application.properties

spring.datasource.url=jdbc:mysql://localhost:3306/<databasename>
spring.datasource.username=<username>
spring.datasource.password=<password>
spring.datasource.driverClassName=com.mysql.cj.jdbc.Driver

User.java (POJO/DAO/JPA)

package com.javatest.demo;

import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;
import jakarta.persistence.Table;

@Entity
@Table(name="users")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private String age;
    private String city;
    private int quota;

    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAge() {
        return age;
    }
    public void setAge(String age) {
        this.age = age;
    }
    public String getCity() {
        return city;
    }
    public void setCity(String city) {
        this.city = city;
    }
    public int getQuota() {
        return quota;
    }
    public void setQuota(int quota) {
        this.quota = quota;
    }


    
    // getters and setters

    
}

UserController.java

package com.javatest.demo;


import java.util.List;

import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.data.jpa.repository.JpaRepository;

interface UserRepository extends JpaRepository<User, Long> {
    // Custom queries can be defined here
}

@RestController
@RequestMapping("users")
public class UserController {
    
    private final UserRepository userRepository;
    
    public UserController(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    @RequestMapping("")
    public String index() {
        return "I am from index";
    }

    @RequestMapping("listing")
    public List<User> listing() {
        // List<User> users = new ArrayList<>();
        return userRepository.findAll();
    }

    @DeleteMapping("delete/{id}")
    public String deleteUser(@PathVariable Long id) {
        // Check if the user with the specified ID exists
        if (userRepository.existsById(id)) {
            userRepository.deleteById(id);
            return String.format("User %s is deleted successfully", id);
        } else {
            // Handle the case when the user does not exist (e.g., return an error response)
            // You can throw an exception or return an appropriate response based on your application's requirements.
        }
        return "";
    }

    @PostMapping("create")
    public User createUser(@RequestBody User user) {
        return userRepository.save(user);
    }


    @GetMapping("get-single/{id}")
    public User getUserById(@PathVariable Long id) {
        // Use the UserRepository to fetch the user by ID
        return userRepository.findById(id).orElse(null);
    }

    @PutMapping("/update/{id}")
    public User updateUser(@PathVariable Long id, @RequestBody User updatedUser) {
        // Check if the user with the specified ID exists
        userRepository.findById(id).orElse(null);

        // Set the ID of the updated user to the specified ID
        updatedUser.setId(id);

        // Save the updated user to the database
        return userRepository.save(updatedUser);
    }

}

DemoApplication.java (Run this file to serve spring boot application)

package com.javatest.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}

}

File Structure

.
├── HELP.md
├── mvnw
├── mvnw.cmd
├── pom.xml
├── src
│   ├── main
│   │   ├── java
│   │   │   └── com
│   │   │       └── javatest
│   │   │           └── demo
│   │   │               ├── CalcController.java
│   │   │               ├── DemoApplication.java
│   │   │               ├── User.java
│   │   │               └── UserController.java
│   │   └── resources
│   │       ├── application.properties
│   │       ├── static
│   │       └── templates
│   └── test
│       └── java
│           └── com
│               └── javatest
│                   └── demo
│                       └── DemoApplicationTests.java
└── target
    ├── classes
    │   ├── application.properties
    │   └── com
    │       └── javatest
    │           └── demo
    │               ├── CalcController.class
    │               ├── DemoApplication.class
    │               ├── MyCalc.class
    │               ├── User.class
    │               ├── UserController.class
    │               └── UserRepository.class
    └── test-classes
        └── com
            └── javatest
                └── demo
                    └── DemoApplicationTests.class

23 directories, 18 files

POC

VSCode Extesnsions

Java Cheat Sheet

Softwares to Install

JDK 11
https://www.oracle.com/in/java/technologies/javase-jdk11-downloads.html

Apache Tomcat Server (version 9)
https://tomcat.apache.org/download-90.cgi

Eclipse EE (2021)
https://www.eclipse.org/downloads/packages/release/neon/3/eclipse-ide-java-ee-developers

Xampp for MySQL (latest version)
https://www.apachefriends.org/download.html

Postman for REST API
https://www.postman.com/downloads/

Addition of Two Numbers

class Main {
	
	public static void main(String args[]) {
		System.out.println(args[0]);
		System.out.println(args[1]);
		
		int num1 = Integer.parseInt(args[0]);
		int num2 = Integer.parseInt(args[1]);

		int add = num1 + num2;
		
		System.out.println(String.format("%s + %s = %s", num1, num2, add));
	}
	
}

Inheritance

class Bank {
	
	protected int balance;
	
	public Bank(int bal) {
		this.balance = bal;
		System.out.println(String.format("Account opened with Balance: %s", this.balance));
	}
	
	public void deposit(int amt) {
		System.out.println(String.format("Deposit Amount: %s", amt));
		this.balance += amt;
	}
	
	public void withdraw(int amt) {
		System.out.println(String.format("Withdraw Amount: %s", amt));
		this.balance -= amt;
	}
	
	public void showBalance() {
		System.out.println(String.format("Available Balance: %s", this.balance));
	}
	
}

class HDFC extends Bank {
	public HDFC(int bal) {
		super(bal);
	}
}

class SBI extends Bank {
	public SBI(int bal) {
		super(bal);
	}
	
	public void withdraw(int amt) {
		super.withdraw(amt);
		super.balance -= 20;
	}
	
}

class Main {
	public static void main(String args[]) {
		Bank bobj = new Bank(1000);
		bobj.showBalance();
		bobj.deposit(500);
		bobj.showBalance();
		bobj.withdraw(300);
		bobj.showBalance();
		
		System.out.println("====================");
		
		HDFC hobj = new HDFC(2000);
		hobj.showBalance();
		hobj.deposit(500);
		hobj.showBalance();
		hobj.withdraw(300);
		hobj.showBalance();
		
		System.out.println("====================");
		
		SBI sobj = new SBI(3000);
		sobj.showBalance();
		sobj.deposit(500);
		sobj.showBalance();
		sobj.withdraw(300);
		sobj.showBalance();
	}
}

Exception Handling

class Main {
	public static void main(String args[]) {
		try {
			
			int num1 = Integer.parseInt(args[0]);
			int num2 = Integer.parseInt(args[1]);
			
			try {
				int div = num1 / num2;
				System.out.println(String.format("Division of %s and %s is %s", num1, num2, div));
			} catch (Exception e) {
				System.out.println(e);
			}
			
			
		} catch (ArrayIndexOutOfBoundsException aie) {
			System.out.println(aie);
			
		} catch (Exception e) {
			System.out.println(e);
		}
		
	}
}

Servlet Demo

Servlet Life Cycle

  1. form.html
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Addition of 2 numbers</title>
<link
	href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.1/dist/css/bootstrap.min.css"
	rel="stylesheet"
	integrity="sha384-+0n0xVW2eSR5OomGNYDnhzAbDsOXxcvSN1TPprVMTNDbiYZCxYbOOl7+AMvyTG2x"
	crossorigin="anonymous">
</head>
<body class="container">
	<form action="CalcServlet" class="m-5">
		<div class="row">
			<div class="col">Number 1</div>
			<div class="col">
				<input type="text" name="num1" placeholder="Enter number" autofocus>
			</div>
		</div>
		<div class="row">
			<div class="col">Number 1</div>
			<div class="col">
				<input type="text" name="num2" placeholder="Enter number">
			</div>
		</div>
		<div class="row">
			<div class="col">
				<input class="btn btn-primary" type="submit" value="Calculate" />
			</div>
		</div>
	</form>
</body>
</html>

2. CalcServlet

import java.io.IOException;
import java.io.PrintWriter;

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

/**
 * Servlet implementation class AddServlet
 */
@WebServlet("/CalcServlet")
public class CalcServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public CalcServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		//response.getWriter().append("Served at: ").append(request.getContextPath());
		int num1 = Integer.parseInt(request.getParameter("num1"));
		int num2 = Integer.parseInt(request.getParameter("num2"));
		
		response.getWriter().write(String.format("%s + %s = %s", num1, num2, num1+num2));
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		//doGet(request, response);
		int num1 = Integer.parseInt(request.getParameter("num1"));
		int num2 = Integer.parseInt(request.getParameter("num2"));
		
		response.getWriter().write(String.format("%s * %s = %s", num1, num2, num1*num2));
	}
	
	protected void doPut(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		//doGet(request, response);
		int num1 = Integer.parseInt(request.getParameter("num1"));
		int num2 = Integer.parseInt(request.getParameter("num2"));
		
		response.getWriter().write(String.format("%s - %s = %s", num1, num2, num1-num2));
	}

	protected void doDelete(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		//doGet(request, response);
		int num1 = Integer.parseInt(request.getParameter("num1"));
		int num2 = Integer.parseInt(request.getParameter("num2"));
		
		response.getWriter().write(String.format("%s / %s = %s", num1, num2, num1/num2));
	}

	protected void doOptions(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		//doGet(request, response);
		int num1 = Integer.parseInt(request.getParameter("num1"));
		int num2 = Integer.parseInt(request.getParameter("num2"));
		
		response.getWriter().write(String.format("%s %% %s = %s", num1, num2, num1%num2));
	}

}

DATABASE SQL

CREATE DATABASE

CREATE DATABASE company;

CREATE TABLE

CREATE TABLE users(
    id INT,
    NAME VARCHAR(100) NOT NULL,
    age TINYINT NOT NULL,
    city VARCHAR(200) NOT NULL
);

ALTER TABLE

ALTER TABLE
    users MODIFY id INT PRIMARY KEY AUTO_INCREMENT;

MySQL JDBC

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class CRUDLDemo {
	public static void main(String args[]) {
		String conn_str = "jdbc:mysql://localhost:3306/company";
		String dbusername = "root";
		String dbpassword = "";

		try {
			Class.forName("com.mysql.cj.jdbc.Driver");
			Connection conn = DriverManager.getConnection(conn_str, dbusername, dbpassword);

			String select_sql = "SELECT * FROM users";
			Statement stmt = conn.createStatement();

			ResultSet rs = stmt.executeQuery(select_sql);

			while (rs.next()) {
				System.out.println(rs.getInt("id"));
				System.out.println(rs.getString("name"));
				System.out.println(rs.getInt("age"));
				System.out.println(rs.getString("city"));
			}

//			String insert_sql = "INSERT INTO users VALUES (NULL, 'Priyanka', 30, 'Mumbai', NOW(), NOW())";
//			Statement stmt = conn.createStatement();
//			int result = stmt.executeUpdate(insert_sql);
//			System.out.println(result);

//			String delete_sql = "DELETE FROM users WHERE id = 3";
//			Statement stmt = conn.createStatement();
//			int result = stmt.executeUpdate(delete_sql);
//			System.out.println(result);

//			String update_sql = "UPDATE users SET city = 'Panvel' WHERE id = 2";
//			Statement stmt = conn.createStatement();
//			int result = stmt.executeUpdate(update_sql);
//			System.out.println(result);

		} catch (Exception e) {
			e.printStackTrace();
		}

	}

}

select.jsp

<%@page import="java.sql.ResultSet"%>
<%@page import="java.sql.Statement"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.Connection"%>
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
	pageEncoding="ISO-8859-1"%>
<% 

String conn_string = "jdbc:mysql://localhost:3306/company";
String db_username = "root";
String db_password = "";

Connection conn = null;

try{
	Class.forName("com.mysql.cj.jdbc.Driver");
	conn = DriverManager.getConnection(conn_string, db_username, db_password);
} catch(Exception e) {
	out.println(e);
}

String select_sql = "SELECT * FROM users";
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(select_sql);

while(rs.next()) {
	out.println(String.format("Id: %s | Name: %s | Age: %s | City: %s<br>", rs.getInt("id"), rs.getString("name"), rs.getInt("age"), rs.getString("city")));
}

%>

insert.jsp

<%@page import="java.sql.Statement"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.Connection"%>
<%
String conn_string = "jdbc:mysql://localhost:3306/company";
String db_username = "root";
String db_password = "";

Connection conn = null;

try{
	Class.forName("com.mysql.cj.jdbc.Driver");
	conn = DriverManager.getConnection(conn_string, db_username, db_password);
} catch(Exception e) {
	out.println(e);
}

String insert_sql = "INSERT INTO users VALUES (NULL, 'Priyanka', 30, 'Mumbai', NOW(), NOW())";
Statement stmt = conn.createStatement();
int result = stmt.executeUpdate(insert_sql);

if(result == 1) {
	out.println("Record inserted successfully...");
} else {
	out.println("Something went wrong...");
}
%>

update.jsp

<%@page import="java.sql.Statement"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.Connection"%>
<%
String conn_string = "jdbc:mysql://localhost:3306/company";
String db_username = "root";
String db_password = "";

Connection conn = null;

try{
	Class.forName("com.mysql.cj.jdbc.Driver");
	conn = DriverManager.getConnection(conn_string, db_username, db_password);
} catch(Exception e) {
	out.println(e);
}

String update_sql = "UPDATE users SET name = 'Palkar' WHERE id = 4";
Statement stmt = conn.createStatement();
int result = stmt.executeUpdate(update_sql);

if(result == 1) {
	out.println("Record updated successfully...");
} else {
	out.println("Something went wrong...");
}
%>

delete.jsp

<%@page import="java.sql.Statement"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.Connection"%>
<%
String conn_string = "jdbc:mysql://localhost:3306/company";
String db_username = "root";
String db_password = "";

Connection conn = null;

try{
	Class.forName("com.mysql.cj.jdbc.Driver");
	conn = DriverManager.getConnection(conn_string, db_username, db_password);
} catch(Exception e) {
	out.println(e);
}

String delete_sql = "DELETE FROM users WHERE id = 4";
Statement stmt = conn.createStatement();
int result = stmt.executeUpdate(delete_sql);

if(result == 1) {
	out.println("Record deleted successfully...");
} else {
	out.println("Something went wrong...");
}
%>

functions.jsp

<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.Connection"%>

<%!
public Connection getConnection() {

		String conn_string = "jdbc:mysql://localhost:3306/company";
		String db_username = "root";
		String db_password = "";

		Connection conn = null;

		try {
			Class.forName("com.mysql.cj.jdbc.Driver");
			conn = DriverManager.getConnection(conn_string, db_username, db_password);
		} catch (Exception e) {
			System.out.println(e);
		}

		return conn;
}

public void authorize(HttpSession session, HttpServletResponse response) {
	
	if(session.getAttribute("username") == null) {
		try {				
			response.sendRedirect("login_form.jsp?msg=Please login to access this page");
			
		} catch(Exception e) {
			e.printStackTrace();
		}
	}
}

%>

include functions and header

<%@include file="functions.jsp" %>
<jsp:include page="header.jsp" />

Hibernate 5.4 Configuration

 

Core Hibernate 5.4 Configuration

<project xmlns="http://maven.apache.org/POM/4.0.0"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>HibernateProj</groupId>
  <artifactId>HibernateProj</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <build>
    <sourceDirectory>src</sourceDirectory>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.8.0</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
    </plugins>
  </build>
  <dependencies>
    <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->
    <dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate-core</artifactId>
      <version>5.4.10.Final</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.15</version>
    </dependency>
  </dependencies>
</project>
<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
    	<!-- <property name="hibernate.current_session_context_class">thread</property> -->
    	<property name="hibernate.current_session_context_class">org.hibernate.context.internal.ThreadLocalSessionContext</property>
        <property name="hibernate.bytecode.use_reflection_optimizer">false</property>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.password"></property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/test</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="show_sql">true</property>
    </session-factory>
</hibernate-configuration>
package com;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.List;

import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;
import org.hibernate.query.Query;

public class MainClass {
  @SuppressWarnings("deprecation")
  public static void main(String[] args) {

    try{  
      Class.forName("com.mysql.cj.jdbc.Driver");  
      Connection con=DriverManager.getConnection(  
          "jdbc:mysql://localhost:3306/test","root","");  
      //here sonoo is database name, root is username and password  
      Statement stmt=con.createStatement();
//			stmt.executeUpdate("insert into emp VALUES (null, 'shailesh', 31, 'Nagpur')");
      ResultSet rs=stmt.executeQuery("select * from emp");  
      while(rs.next())
        System.out.println(rs.getString(1)+"  "+rs.getString(2)+"  "+rs.getString(3)+"  "+rs.getString(4));  
      con.close();  
    } catch(Exception e){ System.out.println(e);}  

    System.out.println("Hibernate connection established successfully...");

    Session session = new Configuration().configure("hibernate.cfg.xml").buildSessionFactory().openSession();
    Query query = session.createNativeQuery("select * from emp");
    List<Student[]> list = query.list();
    System.out.println(list);

    for(Object[] obj : list) {
      Student std = new Student((Integer)obj[0], (String)obj[1], (Integer)obj[2], (String)obj[3]);
      System.out.println(std);
    }		
    ////////////////////////////////////////////////
    Query query2 = session.createNativeQuery("Select id, name, age, city from emp");
    query2.setResultTransformer(Criteria.ALIAS_TO_ENTITY_MAP);
    List<Student> students = query2.list();
    System.out.println(students);
    session.close();
    //==============================//
    Session session2 = new Configuration().configure("database.cfg.xml").buildSessionFactory().openSession();
    List list2 = session2.createNativeQuery("select * from testdmarc").list();
    System.out.println(list2);
  }
}

 

Reference:

https://docs.jboss.org/hibernate/orm/5.4/userguide/html_single/Hibernate_User_Guide.html#sql

https://tools.jboss.org/downloads/jbosstools/2019-09/4.13.0.Final.html#update_site

https://www.tutorialspoint.com/hibernate/hibernate_examples.htm

Hibernate Native SQL Query Example

Servlet File Upload

Ref:
https://www.codejava.net/java-ee/servlet/java-file-upload-example-with-servlet-30-api

https://www.baeldung.com/upload-file-servlet

Servlet 3 File Upload – @MultipartConfig, Part

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;

/**
 * Servlet implementation class MultiPartServlet
 */
@WebServlet("/multiPartServlet")
@MultipartConfig(fileSizeThreshold=1024*1024*10, 	// 10 MB 
maxFileSize=1024*1024*50,      	// 50 MB
maxRequestSize=1024*1024*100)   	// 100 MB
public class MultiPartServlet extends HttpServlet {
  private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public MultiPartServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

  /**
   * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    response.getWriter().append("Served at: ").append(request.getContextPath());
    
    PrintWriter out = response.getWriter();
  }

  private static final String SAVE_DIR = "uploadFiles";
  
  /**
   * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
    // gets absolute path of the web application
        String appPath = request.getServletContext().getRealPath("");
        // constructs path of the directory to save uploaded file
        String savePath = appPath + File.separator + SAVE_DIR;
         
        // creates the save directory if it does not exists
        File fileSaveDir = new File(savePath);
        if (!fileSaveDir.exists()) {
            fileSaveDir.mkdir();
        }
    
    
    for (Part part : request.getParts()) {
        String fileName = extractFileName(part);
//		    part.write(fileName);
        response.getWriter().println("/home/shailesh/eclipse-workspace/TestProject/WebContent/images/" + fileName);
        part.write("/home/shailesh/eclipse-workspace/TestProject/WebContent/images/" + fileName);
    }
    response.getWriter().println("Uploaded...");
    doGet(request, response);
  }
  
  private String extractFileName(Part part) {
      String contentDisp = part.getHeader("content-disposition");
      String[] items = contentDisp.split(";");
      for (String s : items) {
          if (s.trim().startsWith("filename")) {
              return s.substring(s.indexOf("=") + 2, s.length()-1);
          }
      }
      return "";
  }

}

 

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>TestProject</groupId>
  <artifactId>TestProject</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>war</packaging>
  <build>
    <sourceDirectory>src</sourceDirectory>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.8.0</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
      <plugin>
        <artifactId>maven-war-plugin</artifactId>
        <version>3.2.3</version>
        <configuration>
          <warSourceDirectory>WebContent</warSourceDirectory>
        </configuration>
      </plugin>
    </plugins>
  </build>
  <dependencies>
  	<!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
  <dependency>
    	<groupId>org.springframework</groupId>
   	 	<artifactId>spring-webmvc</artifactId>
    	<version>5.2.1.RELEASE</version>
  </dependency>
  
  <!-- Apache Commons FileUpload -->
    <dependency>
        <groupId>commons-fileupload</groupId>
        <artifactId>commons-fileupload</artifactId>
        <version>1.3.2</version>
    </dependency>

    <!-- Apache Commons IO -->
    <dependency>
        <groupId>commons-io</groupId>
        <artifactId>commons-io</artifactId>
        <version>2.5</version>
    </dependency>
  
  </dependencies>
</project>
<form method="post" action="multiPartServlet" enctype="multipart/form-data">
  Choose a file: <input type="file" name="multiPartServlet" />
    <input type="submit" value="Upload" />
</form>

 

Core Java Assignment

Classes and Objects
1. Create class Rectangle
a) data members
– length
– breadth
b) methods
– setDimensions
– area
– perimeter

2. Create class Cube
a) data members
– length
– breadth
– height
b) methods
– setDimensions
– volume

3. Create class Worker
a) data members
– wages
– wdays
b) methods
– setData
– payment

Method Overloading

1. Create class Box
a) data members
– length
– breadth
– height
b) methods
– setDimensions(3 args)
– setDimensions(1 arg)
– volume

Method Returning Value
1. WAP to find total payment of two employeesCreate
Create class Worker
a) data members
– wages
– wdays
b) methods
– setData
– int payment

Constructors
1. Create class Circle and initialize radius using a default constructor
2. Create class Circle and initialize radius using parameterized constructor
3. Create class Circle and define two constructor default and parameterized (Constructor overloading)

Static data members and member functions
1. Create a class Circle and find its area
a) data members
– int radius
– static double pi
b) methods
– area

2. Create a class Bank Account and find interest
a) data members
– int account_number
– int balance
– static double interest_rate
b) methods
– interest (balance * interest_rate * no_of_period / 100.0)
– changeRate (change interest_rate)

OOPS

  1. Design a class Rectangle
    data members[box title=”” bg_color=”#dbdbdb” align=”left”]length
    breadth[/box]member functions/methods[box title=”” bg_color=”#dbdbdb” align=”left”]setDimension()
    area()
    perimeter()[/box]
  2. Design a class Worker
    data members[box title=”” bg_color=”#dbdbdb” align=”left”]wages
    wdays[/box]member function / method[box title=”” bg_color=”#dbdbdb” align=”left”]setData()
    payment()[/box]
  3. Design a class Box
    data members[box title=”” bg_color=”#dbdbdb” align=”left”]length
    breadth
    height[/box]member functions / methods[box title=”” bg_color=”#dbdbdb” align=”left”]setDimension()
    volume()[/box]
  4. Design a class Rectangle (only for Java / C++)
    data members[box title=”” bg_color=”#dbdbdb” align=”left”]length
    breadth[/box] member functions / methods[box title=”” bg_color=”#dbdbdb” align=”left”]setDimension()
    area()
    perimeter()[/box]It must overload setDimension() method twice:
    1. by passing 1 argument
    2. by passing 2 arguments

  5. Design a class Box (only for Java / C++)
    data members[box title=”” bg_color=”#dbdbdb” align=”left”]length
    breadth
    height[/box] member functions / methods [box title=”” bg_color=”#dbdbdb” align=”left”]volume()[/box] It must contain 3 constructors
    1. 1 parameter
    2. 2 parameter
    3. 3 paramter
  6. Design a class Account
    data members [box title=”” bg_color=”#dbdbdb” align=”left”]balance[/box]member functions / methods [box title=”” bg_color=”#dbdbdb” align=”left”] deposit(amt)
    withdraw(amt)
    showBalance()[/box]
  7. Design a class Set
    data members [box title=”” bg_color=”#dbdbdb” align=”left”]3 numbers[/box] member functions / methods [box title=”” bg_color=”#dbdbdb” align=”left”] SUM()
    MEAN()
    MAX()
    MIN() [/box]
  8. Design a class Student
    data members [box title=”” bg_color=”#dbdbdb” align=”left”]roll_number
    name [/box] member functions / methods [box title=”” bg_color=”#dbdbdb” align=”left”] setData()
    getData() [/box]
  9. Design a class Account
    data members [box title=”” bg_color=”#dbdbdb” align=”left”] balance
    interest_rate [/box] interest_rate must be shared by all objects (static modifier) and its default value 10.25 [box title=”” bg_color=”#dbdbdb” align=”left”] interest(no_of_years) [/box]
  10. Design a class Student
    data members [box title=”” bg_color=”#dbdbdb” align=”left”] roll_number
    name [/box] member functions / methods [box title=”” bg_color=”#dbdbdb” align=”left”] setData()
    getData() [/box]
  11. Design a class Account
    [box title=”” bg_color=”#dbdbdb” align=”left”] account_number
    balance
    interest_rate [/box] member functions / methods [box title=”” bg_color=”#dbdbdb” align=”left”] interest(no_of_years) [/box]
  12. Design a class Student
    data members [box title=”” bg_color=”#dbdbdb” align=”left”] roll_number
    name [/box] member function / methods [box title=”” bg_color=”#dbdbdb” align=”left”] getData() [/box] roll_number must be automatically generated.It also keep track of total number of Students.

  13. Design a package MyCircle and MyRectangle (Only for Java)
    [box title=”” bg_color=”#dbdbdb” align=”left”] radius
    length
    breadth [/box] member functions / methods: [box title=”” bg_color=”#dbdbdb” align=”left”] area()
    circumference()
    perimeter() [/box]
  14. Design a class Student
    data members [box title=”” bg_color=”#dbdbdb” align=”left”] roll_number
    name [/box] member functions / methods [box title=”” bg_color=”#dbdbdb” align=”left”] getData()
    showData() [/box] Create 5 objects of Student using Array

  15. Design a class Student and List ClassRoom
    add list of Students in ClassRoom
    display List

  16. Design a class Account and List Bank
    add list of Account in Bank
    display List

  17. Create array of Student Objects
    data members [box title=”” bg_color=”#dbdbdb” align=”left”] roll_no
    name
    college [/box] member functions / methods [box title=”” bg_color=”#dbdbdb” align=”left”] readData()
    showData() [/box]
  18. Create a class RBI (Only for Java)
    data members [box title=”” bg_color=”#dbdbdb” align=”left”] balance [/box] member functions [box title=”” bg_color=”#dbdbdb” align=”left”] RBI()
    deposit(int amt)
    withdraw(int amt)
    showBalance() [/box]