響應式 Spring WebClient 調用

Question

我正在嘗試了解 WebFlux，但在 Webclient 調用方面遇到了一些麻煩。 我沒有看到這一行 System.out.println("customerId = " + customerId); 執行它似乎沒有調用端點。 但是如果我用 .subscribe(customer -> {}); 訂閱 webclient; 然后我可以看到這一行 System.out.println("customerId = " + customerId); 在端點端工作。 我不明白為什么我必須訂閱 Mono 調用，還是必須訂閱？ 謝謝

@GetMapping("/customer/{customerId}")
@ResponseStatus(HttpStatus.ACCEPTED)
public Mono<Void> getCustomer(@PathVariable("customerId") int customerId) {
     WebClient webClient = WebClient.builder().baseUrl("http://localhost:8080").build();

 webClient.get()
  .uri("/client/customer/{customerId}",customerId)
  .accept(MediaType.APPLICATION_JSON)
  .retrieve()
  .bodyToMono(Customer.class);//here do I have to subscribe to actually activate to call?

 return null;
}


@GET
@Path("/customer/{customerId}")
@Produces(MediaType.APPLICATION_JSON)
public Customer getCustomer(@PathParam("customerId") int customerId) throws InterruptedException {
    System.out.println("customerId = " + customerId);  // I do not see the call comes thru if I dont subscribe to flux call.
    return new Customer(customerId,"custName");
} 

Answer 1

如果要從WebClient返回反應類型，則必須從控制器方法返回它，例如：

@GetMapping("/customer/{customerId}")
@ResponseStatus(HttpStatus.ACCEPTED)
public Mono<Customer> getCustomer(@PathVariable("customerId") int customerId) {
     WebClient webClient = WebClient.builder().baseUrl("http://localhost:8080").build();

 return webClient.get()
  .uri("/client/customer/{customerId}",customerId)
  .accept(MediaType.APPLICATION_JSON)
  .retrieve()
  .bodyToMono(Customer.class);
}

您還可以從您的端點返回一個Customer並阻止並等待您的WebClient的結果並離開響應式生態系統，例如：

@GetMapping("/customer/{customerId}")
@ResponseStatus(HttpStatus.ACCEPTED)
public Customer getCustomer(@PathVariable("customerId") int customerId) {
     WebClient webClient = WebClient.builder().baseUrl("http://localhost:8080").build();

 return webClient.get()
  .uri("/client/customer/{customerId}",customerId)
  .accept(MediaType.APPLICATION_JSON)
  .retrieve()
  .bodyToMono(Customer.class)
  .block()
}

如果您正在查看 Spring 的WebClient的一般介紹，請查看本教程