Exploring the Power of WebClient in Spring Boot: A Comprehensive Guide

2 min readApr 17, 2023

Introduction

WebClient is a non-blocking HTTP client that is part of the Spring WebFlux framework. It allows us to make HTTP requests to external APIs and microservices asynchronously, without blocking the application’s main thread. In this article, we’ll explore the power of WebClient in Spring Boot and learn how to use it to make HTTP requests, handle responses, and more.

Getting Started

Before we can use WebClient, we need to add the necessary dependencies to our Spring Boot project. We can do this by adding the spring-boot-starter-webflux dependency to our build file. Once we have the dependencies, we can create an instance of WebClient and start making HTTP requests.

Making HTTP Requests

To make an HTTP request using WebClient, we need to specify the HTTP method, URL, and any additional headers or parameters. For example, to make a GET request to an external API, we can use the following code:

WebClient webClient = WebClient.create();
Mono<String> result = webClient.get()
        .uri("https://api.example.com/data")
        .retrieve()
        .bodyToMono(String.class);

Handling Responses

WebClient returns a reactive type Mono or Flux, depending on the expected response type. We can use the bodyToMono() or bodyToFlux() methods to convert the response body to the desired type. For example, to convert the response body to a JSON object, we can use the following code:

Mono<MyObject> result = webClient.get()
        .uri("https://api.example.com/data")
        .retrieve()
        .bodyToMono(MyObject.class);

Error Handling

WebClient also allows us to handle errors that occur during the HTTP request. We can use the onErrorResume() or onErrorReturn() methods to specify how to handle the error. For example, to return a default value if an error occurs, we can use the following code:

Mono<MyObject> result = webClient.get()
        .uri("https://api.example.com/data")
        .retrieve()
        .onErrorResume(e -> Mono.just(new MyObject()))
        .bodyToMono(MyObject.class);

Conclusion

In this article, we explored the power of WebClient in Spring Boot and learned how to use it to make HTTP requests, handle responses, and more. With WebClient, we can make HTTP requests asynchronously and improve the performance of our Spring Boot applications. If you haven’t already, we encourage you to try WebClient in your own projects and see the benefits for yourself.