**Course Title:** Comprehensive Java Programming: From Basics to Advanced Concepts **Section Title:** Web Development with Java **Topic:** Create a simple web application using Spring Boot to expose a REST API and handle client requests. (Lab topic) **Objective:** By the end of this lab, you will learn how to create a simple web application using Spring Boot to expose a REST API and handle client requests. **Prerequisites:** * Familiarity with Java and its ecosystem * Understanding of RESTful APIs and HTTP methods * Knowledge of Maven or Gradle build tools * Prior experience with Spring Boot is not required, but it's a plus **Software Requirements:** * Java Development Kit (JDK) 11 or later * Spring Boot 2.7.3 or later * Maven 3 or later (or Gradle 7.5 or later) * Any IDE of your choice (e.g., IntelliJ IDEA, Eclipse, Visual Studio Code) ### Step 1: Set up a new Spring Boot project To create a new Spring Boot project, you can use the official Spring Initializr web tool. Follow these steps: * Go to [https://start.spring.io/](https://start.spring.io/) * Select "Web" as the project type * Choose "Maven" or "Gradle" as the build tool * Select "Java" as the language * Click on "Generate Project" to download the project ZIP file Alternatively, you can create a new Spring Boot project from your IDE. ### Step 2: Create a new REST API endpoint Create a new Java class `User.java` to represent a simple user entity: ```java // src/main/java/com/example/demo/User.java public class User { private String id; private String name; private String email; // getters and setters public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } } ``` Create a new Java class `UserController.java` to handle REST API requests: ```java // src/main/java/com/example/demo/UserController.java import org.springframework.web.bind.annotation.*; @RestController @RequestMapping("/users") public class UserController { @GetMapping public String getAllUsers() { return "List of all users"; } @GetMapping("/{id}") public String getUser(@PathVariable String id) { return "User with ID " + id; } @PostMapping public String createUser(@RequestBody User user) { return "User created successfully"; } @PutMapping("/{id}") public String updateUser(@PathVariable String id, @RequestBody User user) { return "User updated successfully"; } @DeleteMapping("/{id}") public String deleteUser(@PathVariable String id) { return "User deleted successfully"; } } ``` ### Step 3: Configure Spring Boot application properties Create a new file `application.properties` to configure the Spring Boot application: ```properties # src/main/resources/application.properties server.port=8080 server.servlet.context-path=/api spring.datasource.url=jdbc:mysql://localhost:3306/demo spring.datasource.username=root spring.datasource.password=password spring.jpa.hibernate.ddl-auto=update ``` ### Step 4: Run the Spring Boot application Run the Spring Boot application using the `mvn spring-boot:run` (or `gradle bootRun`) command. You should see the application start and the REST API endpoints exposed. **Conclusion:** You have successfully created a simple web application using Spring Boot to expose a REST API and handle client requests. You can now use a tool like Postman or cURL to test the API endpoints. **What's next?** In the next topic, we will cover unit testing in Java using JUnit. We will learn how to write unit tests for the Spring Boot application and use mocking libraries to isolate dependencies. **Questions or comments?** If you have any questions or need help with the lab, please leave a comment below. We'll be happy to help! **External Resources:** * Spring Boot official documentation: [https://spring.io/projects/spring-boot](https://spring.io/projects/spring-boot) * Spring Boot API documentation: [https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#boot-features-developing-web-applications](https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#boot-features-developing-web-applications) * RESTful API tutorial: [https://restfulapi.net/](https://restfulapi.net/)