Sr. No.	Topic	Details Covered
1	Introduction to Java & Spring Boot	Java Fundamentals RevisionJDK, JRE, JVMMaven BasicsSpring Framework OverviewSpring Boot Architecture
2	Spring Boot Project Setup	Spring InitializrProject Structureapplication.propertiesRunning First Spring Boot Application
3	REST API Development	ControllersRequest MappingPath VariablesQuery ParametersRequest BodyResponseEntity
4	Dependency Injection & Bean Management	@Component@Service@Repository@AutowiredConstructor InjectionBean Lifecycle
5	Database Integration	MySQL SetupSpring Data JPAEntity MappingRepository LayerCRUD Operations
6	DTO & Validation	DTO PatternRequest DTOResponse DTOModel MappingBean ValidationException Handling
7	Service Layer & Business Logic	Layered ArchitectureService DesignBusiness Logic ImplementationTransaction ManagementBest Practices
8	Advanced JPA Concepts	One-to-One MappingOne-to-Many MappingMany-to-One MappingFetch TypesPaginationSorting
9	Security Basics	Spring Security IntroductionAuthenticationAuthorizationPassword Encoding
10	JWT Authentication	JWT ArchitectureToken GenerationToken ValidationSecuring REST APIs
11	Logging & Monitoring	SLF4JLogbackApplication LoggingSpring Boot ActuatorHealth Checks
12	Testing	JUnit 5MockitoService Layer TestingController TestingAPI Testing
13	API Documentation	Swagger/OpenAPIAPI DocumentationSwagger UI Testing
14	Build & Deployment	Maven Build LifecycleJAR PackagingEnvironment ConfigurationLinux Deployment
15	Version Control	Git BasicsGit BranchingMerge & Pull RequestsGitHub Workflow
16	Mini Project Development	Project SetupDatabase DesignREST API DevelopmentSecurity ImplementationTesting
17	Project Review	Code ReviewPerformance ImprovementsBest Practices
18	Interview Preparation	Spring Boot Interview QuestionsJPA QuestionsREST API QuestionsMicroservices Overview

Sr. No.	Tool / Technology
1	Java 17+
2	Spring Boot
3	Maven
4	MySQL
5	Spring Data JPA
6	Spring Security
7	JWT
8	Postman
9	Swagger/OpenAPI
10	Git & GitHub
11	VSCode, IntelliJ IDEA / Eclipse

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

Spring Boot Web + JPA + MySQL

Got it ✅
Let’s build this from scratch, step by step, including MySQL dependency so you’re future-ready but you can still just run Hello World without DB config.

---

🚀 Spring Boot Hello World (with future MySQL support) in VS Code

1. Prerequisites

Check you have these installed:

java -version      # Java 17 or 21 recommended
mvn -v             # Maven installed

VS Code Extensions:

• Extension Pack for Java
• Spring Boot Extension Pack (optional but helpful)

---

2. Generate Spring Boot Project

Option A (VS Code)

1. Press Ctrl+Shift+P → search Spring Initializr: Create a Maven Project.
2. Select:
   • Spring Boot version: 3.x (latest)
   • Project: Maven
   • Language: Java
   • Group Id: com.example
   • Artifact Id: hello
   • Dependencies: Spring Web, Spring Data JPA, MySQL Driver
3. It will create and open the project in VS Code.

Option B (Browser)

Go to 👉 https://start.spring.io
Choose:

• Maven Project, Java, Spring Boot 3.x
• Group: com.example
• Artifact: hello
• Dependencies: Spring Web, Spring Data JPA, MySQL Driver
  Download → unzip → open folder in VS Code.

src/main/resources/application.properties

spring.datasource.url=jdbc:mysql://localhost:3306/your_database
spring.datasource.username=root
spring.datasource.password=your_password

spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.database-platform=org.hibernate.dialect.MySQLDialect

---

3. Project Structure

You’ll see:

hello/
 ├─ src/main/java/com/example/hello/
 │   ├─ HelloApplication.java
 │   └─ controller/HelloController.java   (we’ll create)
 ├─ src/main/resources/
 │   ├─ application.properties
 ├─ pom.xml

---

4. Minimal pom.xml

Your pom.xml should contain (important part only):

<dependencies>
    <!-- Spring Web for REST APIs -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <!-- MySQL JDBC Driver -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <scope>runtime</scope>
    </dependency>

    <!-- JPA (for DB support in future) -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>

    <!-- Testing -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

⚡ Even if MySQL is not configured, the app will still run fine.

---

5. Application Entry Point

Generated file → HelloApplication.java:

package com.example.hello;

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

@SpringBootApplication
public class HelloApplication {

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

---

6. Create Controller

Create folder controller under com.example.hello.
File: HelloController.java

package com.example.hello.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

    @GetMapping("/hello")
    public String hello() {
        return "Hello World";
    }
}

---

7. Run the Application

In VS Code terminal:

mvn spring-boot:run

Or run HelloApplication.java directly via Run → Start Debugging.

---

8. Test in Browser / Curl

Visit:

http://localhost:8080/hello

Output:

Hello World

---

9. (Future) MySQL Connection Setup

When you’re ready to use MySQL, edit src/main/resources/application.properties:

spring.datasource.url=jdbc:mysql://localhost:3306/mydb
spring.datasource.username=root
spring.datasource.password=secret

spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL8Dialect

Then you can create Entity + Repository classes for DB operations.

---

10. Employee POJO / Repo / Controller

src/main/java/com/example/demo/Employee.java

package com.example.demo;

import jakarta.persistence.*;

@Entity
@Table(name = "employee")
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;
    private String department;
    private Double salary;

    // getters & setters
    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 getDepartment() { return department; }
    public void setDepartment(String department) { this.department = department; }

    public Double getSalary() { return salary; }
    public void setSalary(Double salary) { this.salary = salary; }
    
}

src/main/java/com/example/demo/EmployeeRepository.java

package com.example.demo;

import org.springframework.data.jpa.repository.JpaRepository;

public interface EmployeeRepository extends JpaRepository<Employee, Long> {
}

src/main/java/com/example/demo/EmployeeController.java

package com.example.demo;

import org.springframework.web.bind.annotation.*;

import java.util.List;

@CrossOrigin(origins = "*")
@RestController
@RequestMapping("/employees")
public class EmployeeController {

    private final EmployeeRepository employeeRepository;

    public EmployeeController(EmployeeRepository employeeRepository) {
        this.employeeRepository = employeeRepository;
    }

    // ✅ CREATE (POST)
    @PostMapping
    public Employee createEmployee(@RequestBody Employee employee) {
        return employeeRepository.save(employee);
    }

    // ✅ READ ALL (GET)
    @GetMapping
    public List<Employee> getAllEmployees() {
        return employeeRepository.findAll();
    }

    // ✅ READ BY ID (GET)
    @GetMapping("/{id}")
    public Employee getEmployeeById(@PathVariable Long id) {
        return employeeRepository.findById(id).orElse(null);
    }

    // ✅ UPDATE (PUT)
    @PutMapping("/{id}")
    public Employee updateEmployee(
            @PathVariable Long id,
            @RequestBody Employee updatedEmployee) {

        Employee existing = employeeRepository.findById(id).orElse(null);

        if (existing == null) {
            return null;
        }

        existing.setName(updatedEmployee.getName());
        existing.setDepartment(updatedEmployee.getDepartment());
        existing.setSalary(updatedEmployee.getSalary());

        return employeeRepository.save(existing);
    }

    // ✅ DELETE (DELETE)
    @DeleteMapping("/{id}")
    public String deleteEmployee(@PathVariable Long id) {

        if (!employeeRepository.existsById(id)) {
            return "Employee not found";
        }

        employeeRepository.deleteById(id);
        return "Employee deleted successfully";
    }
}

frontend/index.html

<!DOCTYPE html>
<html>
<head>
    <title>Employee CRUD</title>
    <style>
        table {
            border-collapse: collapse;
            width: 70%;
            margin-top: 20px;
        }
        th, td {
            border: 1px solid #333;
            padding: 8px;
        }
        th {
            background-color: #f2f2f2;
        }
        button {
            margin-right: 5px;
        }
        input {
            margin: 5px;
        }
    </style>
</head>
<body>

<h2>Employee Management</h2>

<!-- ADD / EDIT FORM -->
<input type="hidden" id="empId">

<input type="text" id="name" placeholder="Name">
<input type="text" id="department" placeholder="Department">
<input type="number" id="salary" placeholder="Salary">

<button onclick="saveEmployee()">Add / Update</button>

<!-- TABLE -->
<table>
    <thead>
        <tr>
            <th>ID</th>
            <th>Name</th>
            <th>Department</th>
            <th>Salary</th>
            <th>Action</th>
        </tr>
    </thead>
    <tbody id="employeeTable"></tbody>
</table>

<script>
    const apiUrl = "http://localhost:8080/employees";

    function loadEmployees() {
        fetch(apiUrl)
            .then(res => res.json())
            .then(data => {
                const table = document.getElementById("employeeTable");
                table.innerHTML = "";

                data.forEach(emp => {
                    table.innerHTML += `
                        <tr>
                            <td>${emp.id}</td>
                            <td>${emp.name}</td>
                            <td>${emp.department}</td>
                            <td>${emp.salary}</td>
                            <td>
                                <button onclick="editEmployee(${emp.id}, '${emp.name}', '${emp.department}', ${emp.salary})">Edit</button>
                                <button onclick="deleteEmployee(${emp.id})">Delete</button>
                            </td>
                        </tr>
                    `;
                });
            });
    }

    function saveEmployee() {
        const id = document.getElementById("empId").value;
        const employee = {
            name: document.getElementById("name").value,
            department: document.getElementById("department").value,
            salary: document.getElementById("salary").value
        };

        if (id) {
            // UPDATE
            fetch(`${apiUrl}/${id}`, {
                method: "PUT",
                headers: { "Content-Type": "application/json" },
                body: JSON.stringify(employee)
            }).then(() => resetForm());
        } else {
            // CREATE
            fetch(apiUrl, {
                method: "POST",
                headers: { "Content-Type": "application/json" },
                body: JSON.stringify(employee)
            }).then(() => resetForm());
        }
    }

    function editEmployee(id, name, department, salary) {
        document.getElementById("empId").value = id;
        document.getElementById("name").value = name;
        document.getElementById("department").value = department;
        document.getElementById("salary").value = salary;
    }

    function deleteEmployee(id) {
        if (confirm("Are you sure?")) {
            fetch(`${apiUrl}/${id}`, { method: "DELETE" })
                .then(() => loadEmployees());
        }
    }

    function resetForm() {
        document.getElementById("empId").value = "";
        document.getElementById("name").value = "";
        document.getElementById("department").value = "";
        document.getElementById("salary").value = "";
        loadEmployees();
    }

    // Load on page load
    loadEmployees();
</script>

</body>
</html>

✅ That’s it — you now have:

• A working Hello World REST API (/hello)
• MySQL support already included for future use