Hackforge Academy

Explanation

WebClient is a modern, non-blocking HTTP client introduced in Spring WebFlux. It is the recommended replacement for RestTemplate and supports reactive programming for better scalability and performance.

Code:

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

Explanation

Create a WebClient bean to communicate with external APIs. This bean can be injected into services or controllers throughout the application.

Code:

@Configuration
public class WebClientConfig {

    @Bean
    public WebClient webClient() {
        return WebClient.builder().build();
    }
}

Explanation

The get() method is used to make HTTP GET requests. The response body can be retrieved as a Mono, which represents an asynchronous single value.

Code:

@Autowired
private WebClient webClient;

Mono<String> response = webClient.get()
        .uri("https://jsonplaceholder.typicode.com/posts/1")
        .retrieve()
        .bodyToMono(String.class);

Explanation

WebClient responses can be mapped directly to Java objects. This eliminates manual JSON parsing and provides type-safe access to API data.

Code:

public class Post {
    private Long id;
    private String title;
    private String body;

    // Getters and Setters
}

Mono<Post> post = webClient.get()
        .uri("https://jsonplaceholder.typicode.com/posts/1")
        .retrieve()
        .bodyToMono(Post.class);

Explanation

A REST API can consume an external service and return the response to clients. Using WebClient, the call remains non-blocking, improving application throughput.

Code:

@RestController
@RequestMapping("/posts")
public class PostController {

    @Autowired
    private WebClient webClient;

    @GetMapping("/{id}")
    public Mono<String> getPost(@PathVariable Long id) {
        return webClient.get()
                .uri("https://jsonplaceholder.typicode.com/posts/" + id)
                .retrieve()
                .bodyToMono(String.class);
    }
}