Lembar Cheat WebClient Boot Musim Semi

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WebClient — , HTTP-.

RestTemplate

, , RestTemplate . :

NOTE: As of 5.0 this class is in maintenance mode, with only minor requests for changes and bugs to be accepted going forward. Please, consider using the org.springframework.web.reactive.client.WebClient



which has a more modern API and supports sync, async, and streaming scenarios.

: 5.0, . , org.springframework.web.reactive.client.WebClient



, API , .

, , RestTemplate , . , WebClient . . 

WebClient RestTemplate

, , RestTemplate (), WebClient ( ).

RestTemplate — HTTP-, API HTTP-, HttpURLConnection



(JDK), HttpComponents



(Apache) .

Spring WebClient — , HTTP-, Spring WebFlux.

, , , . WebClient . WebClient. 

RestTemplate , WebClient.

WebClient

• Spring Boot 2

  
  
  
  
  

• JDK 11

  
  
  
  
  

, Spring Initializr.

. —  spring-boot-starter-webflux



.

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

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

Spring WebFlux Spring 5 -.

WebClient.

WebClient

WebClient. — .

WebClient client = WebClient.create();
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

URL:

WebClient client = WebClient.create("http://base-url.com");
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

— WebClient . , URL .

@Configuration
public class WebClientConfiguration {
    private static final String BASE_URL = "https://jsonplaceholder.typicode.com";
    public static final int TIMEOUT = 1000;

    @Bean
    public WebClient webClientWithTimeout() {
        final var tcpClient = TcpClient
                .create()
                .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, TIMEOUT)
                .doOnConnected(connection -> {
                    connection.addHandlerLast(new ReadTimeoutHandler(TIMEOUT, TimeUnit.MILLISECONDS));
                    connection.addHandlerLast(new WriteTimeoutHandler(TIMEOUT, TimeUnit.MILLISECONDS));
                });

        return WebClient.builder()
                .baseUrl(BASE_URL)
                .clientConnector(new ReactorClientHttpConnector(HttpClient.from(tcpClient)))
                .build();
    }
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, WebClient.Builder .

Spring WebClient

WebClient : get()



, post()



, put()



, patch()



, delete()



, options()



head()



.

:

• (path variables
  
  
  
  ) uri()
  
  
  
  .

  
  
  
  
  

• headers()
  
  
  
  .

  
  
  
  
  

• cookies()
  
  
  
  .

  
  
  
  
  

retrieve()



exchange()



. Mono bodyToMono()



Flux bodyToFlux()



.

, WebClient .

@Service
@AllArgsConstructor
public class UserService {
    private final WebClient webClient;

    public Mono<User> getUserByIdAsync(final String id) {
        return webClient
                .get()
                .uri(String.join("", "/users/", id))
                .retrieve()
                .bodyToMono(User.class);
    }
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, User. User Mono-, . , subscribe()



.

userService
  .getUserByIdAsync("1")
  .subscribe(user -> log.info("Get user async: {}", user));
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

subscribe()



, .

, block()



.

public User getUserByIdSync(final String id) {
    return webClient
            .get()
            .uri(String.join("", "/users/", id))
            .retrieve()
            .bodyToMono(User.class)
            .block();
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, . .

, . . retryWhen()



, response.util.retry.Retry



.

public User getUserWithRetry(final String id) {
    return webClient
            .get()
            .uri(String.join("", "/users/", id))
            .retrieve()
            .bodyToMono(User.class)
            .retryWhen(Retry.fixedDelay(3, Duration.ofMillis(100)))
            .block();
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

(, ). , repeatWhen()



repeatWhenEmpty()



retryWhen()



.

, , . :

• doOnError()
  
  
  
  — , Mono .

  
  
  
  
  

• onErrorResume()
  
  
  
  — , .

  
  
  
  
  

, , .

public User getUserWithFallback(final String id) {
    return webClient
            .get()
            .uri(String.join("", "/broken-url/", id))
            .retrieve()
            .bodyToMono(User.class)
            .doOnError(error -> log.error("An error has occurred {}", error.getMessage()))
            .onErrorResume(error -> Mono.just(new User()))
            .block();
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

. onStatus()



.

public User getUserWithErrorHandling(final String id) {
  return webClient
          .get()
          .uri(String.join("", "/broken-url/", id))
          .retrieve()
              .onStatus(HttpStatus::is4xxClientError,
                      error -> Mono.error(new RuntimeException("API not found")))
              .onStatus(HttpStatus::is5xxServerError,
                      error -> Mono.error(new RuntimeException("Server is not responding")))
          .bodyToMono(User.class)
          .block();
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

WebClient .

WebClient.builder()
  .baseUrl(BASE_URL)
  .filter((request, next) -> next
          .exchange(ClientRequest.from(request)
                  .header("foo", "bar")
                  .build()))
  .clientConnector(new ReactorClientHttpConnector(HttpClient.from(tcpClient)))
  .build();
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

.

WebClient.builder()
  .baseUrl(BASE_URL)
  .filter(basicAuthentication("user", "password")) // org.springframework.web.reactive.function.client.basicAuthentication()
  .clientConnector(new ReactorClientHttpConnector(HttpClient.from(tcpClient)))
  .build();
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, WebClient HTTP-. , , GitHub-. Spring WebClient .

, , WebClient , .

Spring WebClient!

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