Spring Cloud Circuit Breaker 使用示例

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-webflux</artifactId>

        </dependency>

然后暴露一个简单服务

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RestController;

import reactor.core.publisher.Mono;

@RestController

public class BookController {

    @RequestMapping(value = "/recommended")

    public Mono<String> readingList() {

        return Mono.just("book1,book2,book3");

    }

}

暴露端口

server.port=8090

客户端的配置也很简单，核心在ReactiveCircuitBreaker的初始化，客户端的依赖如下

        <dependency>

            <groupId>org.springframework.cloud</groupId>

            <artifactId>spring-cloud-starter-circuitbreaker-reactor-resilience4j</artifactId>

        </dependency>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-webflux</artifactId>

        </dependency>

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import org.springframework.cloud.client.circuitbreaker.ReactiveCircuitBreaker;

import org.springframework.cloud.client.circuitbreaker.ReactiveCircuitBreakerFactory;

import org.springframework.stereotype.Service;

import org.springframework.web.reactive.function.client.WebClient;

import reactor.core.publisher.Mono;

@Service

public class BookService {

    private static final Logger LOG = LoggerFactory.getLogger(BookService.class);

    private final WebClient webClient;

    private final ReactiveCircuitBreaker readingListCircuitBreaker;

    public BookService(ReactiveCircuitBreakerFactory circuitBreakerFactory) {

        this.webClient = WebClient.builder().baseUrl("http://localhost:8090").build();

        this.readingListCircuitBreaker = circuitBreakerFactory.create("recommended");

    }

    public Mono<String> readingList() {

        return readingListCircuitBreaker.run(webClient.get().uri("/recommended").retrieve().bodyToMono(String.class), throwable -> {

            LOG.warn("Error making request to book service", throwable);

            return Mono.just("local store book");

        });

    }

}

如果需要配置一些熔断条件，则做如下设置即可

CircuitBreakerConfig circuitBreakerConfig = CircuitBreakerConfig.custom()

  .failureRateThreshold(50)

  .waitDurationInOpenState(Duration.ofMillis(1000))

  .slidingWindowSize(2)

  .build();

TimeLimiterConfig timeLimiterConfig = TimeLimiterConfig.custom()

  .timeoutDuration(Duration.ofSeconds(4))

  .build();

this.readingListCircuitBreaker = circuitBreakerFactory.configureDefault(

                id -> new Resilience4JConfigBuilder(id)

                .timeLimiterConfig(timeLimiterConfig)

                .circuitBreakerConfig(circuitBreakerConfig)

客户端暴露一个接口用于测试

@RestController

public class ReadingController {

    private final BookService bookService;

    public ReadingController(BookService bookService) {

        this.bookService = bookService;

    }

    @RequestMapping("/to-read")

    public Mono<String> toRead() {

        return bookService.readingList();

    }

}

客户端设置端口