Spring Examples - Webflux

Step 1: Maven Dependencies

Create a Spring Boot spplication with the latest version of spring webflux in the POM.xml. To see how to create a spring application you can visit Spring Example - HelloWorld

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-webflux</artifactId>
</dependency>

Step 2: User Entity

Add the User class to provide the entity objects which the application must deliver

public class User {
	private String id;
  private String name;
    
	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;
	}
}

Step 3: UserRepository

add the repository UserRepository to provide the entities that we need to send via the controller in the last step. it has these two main functions:

• Mono<User> findUserById(String id)
• Flux<User> findAllUsers()

@Repository
public class UserRepository {
    static Map<String,User> userData;
    static {
        userData = new HashMap<>();
        userData.put("1",new User("1","User 1"));
        userData.put("2",new User("2","User 2"));
		}
    public Mono<User> findUserById(String id) {
        return Mono.just(userData.get(id));
    }
    
    public Flux<User> findAllUsers() {
        return Flux.fromIterable(userData.values());
    }
}		

Step 4: WebfluxController

Generate WebfluxController with 3 mapping:

• @GetMapping("/"): to deliver a simple string as the response
• @GetMapping("/{id}"): to deliver one object using Mono
• @GetMapping("/all"): to deliver an array of objects using Flux

@RestController
public class WebfluxController {
   
    @GetMapping("/")
    public Publisher<String> home() {
        return Mono.just("Home page");
    }

    @GetMapping("/{id}")
    private Mono<User> getUserById(@PathVariable String id) {
        return userRepository.findUserById(id);
    }

    @GetMapping("/all")
    private Flux<User> getAllUsers() {
        return userRepository.findAllUsers();
    }
}

Step 5: Run the application

Run the application and access it by calling the implemeted endpoints:

http://127.0.0.1:8080/
http://127.0.0.1:8080/1
http://127.0.0.1:8080/all