What are the differences between using RestTemplate and WebClient in Spring for making HTTP requests?

RestTemplate and WebClient are two ways to perform HTTP requests in Spring, but they have key differences:

• RestTemplate is a synchronous client that blocks the thread until a response is received. It is simpler to use for basic scenarios but does not support reactive programming.

• WebClient is an asynchronous and reactive client that does not block the thread and is better suited for high-load and scalable applications. It supports reactive data types and allows more flexible management of requests and responses.

If the application uses Spring WebFlux or requires high performance and scalability, WebClient is preferable. For simple and traditional applications, RestTemplate may be sufficient.

Example of using WebClient:

WebClient client = WebClient.create("https://api.example.com");
String response = client.get()
    .uri("/data")
    .retrieve()
    .bodyToMono(String.class)
    .block(); // blocks to get the result synchronously