請(qǐng)求重試

創(chuàng)建springboot項(xiàng)目，選擇web、eureka-client依賴，創(chuàng)建完成后添加resilience4j依賴

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
<dependency>
    <groupId>io.github.resilience4j</groupId>
    <artifactId>resilience4j-spring-boot2</artifactId>
    <version>1.2.0</version>
    <exclusions>
        <exclusion>
            <groupId>io.github.resilience4j</groupId>
            <artifactId>resilience4j-circuitbreaker</artifactId>
        </exclusion>
        <exclusion>
            <groupId>io.github.resilience4j</groupId>
            <artifactId>resilience4j-ratelimiter</artifactId>
        </exclusion>
        <exclusion>
            <groupId>io.github.resilience4j</groupId>
            <artifactId>resilience4j-bulkhead</artifactId>
        </exclusion>
        <exclusion>
            <groupId>io.github.resilience4j</groupId>
            <artifactId>resilience4j-timelimiter</artifactId>
        </exclusion>
    </exclusions>
</dependency>

注意：resilience4j-spring-boot2中包含了resilience4j中所有的功能，未配置的功能無(wú)法正常使用，所以要將其他組件先從依賴中排除。

新建yml文件，配置retry，并將該服務(wù)注冊(cè)到erueka

resilience4j:
  retry:
    retry-aspect-order: 399 # 表示retry優(yōu)先級(jí)，一般retry優(yōu)先級(jí)高于限流和斷路器
    backends:
      retryA:
        maxRetryAttempts: 5 # 重試次數(shù)
        waitDuration: 500 # 重試等待時(shí)間
        exponentialBackoffMultipliter: 1.1 # 間隔乘數(shù)
        retryException:
          - java.lang.RuntimeException
spring:
  application:
    name: resilience4j
server:
  port: 5000
eureka:
  client:
    service-url:
      defaultZone: http://localhost:1111/eureka

新建Service，調(diào)用provider中的接口，聲明使用重試策略的名稱

@Service
@Retry(name = "retryA")
public class HelloService {
    @Autowired
    RestTemplate restTemplate;
    public String hello(){
        return restTemplate.getForObject("http://localhost:1113/hello",String.class);

    }
}

最后編寫(xiě)測(cè)試接口，進(jìn)行測(cè)試，可以看到方法共執(zhí)行了五次。

circuitbreaker

現(xiàn)在依賴中刪除對(duì)circuitbreaker組件的排除

        <dependency>
            <groupId>io.github.resilience4j</groupId>
            <artifactId>resilience4j-spring-boot2</artifactId>
            <version>1.2.0</version>
            <exclusions>
                <exclusion>
                    <groupId>io.github.resilience4j</groupId>
                    <artifactId>resilience4j-ratelimiter</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>io.github.resilience4j</groupId>
                    <artifactId>resilience4j-bulkhead</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>io.github.resilience4j</groupId>
                    <artifactId>resilience4j-timelimiter</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

在yml中配置circuitbreaker實(shí)例

circuitbreaker:
    instances:
      cbA:
        ringBufferSizeInClosedState: 5
        ringBufferSizeInHalfOpenState: 3
        waitInterval: 5000
        recordExceptions:
          - org.springframework.web.client.HttpServerErrorException

在service中添加服務(wù)降級(jí)的方法，并在@CircuitBreaker注解中聲明斷路器的策略和服務(wù)降級(jí)返回的方法。

@Service
@CircuitBreaker(name = "cbA",fallbackMethod = "error")
public class HelloService {
    @Autowired
    RestTemplate restTemplate;
    public String hello(){
        return restTemplate.getForObject("http://localhost:1113/hello",String.class);
    }

    public String error(Throwable t){
        return "error";
    }
}

訪問(wèn)測(cè)試接口可以看到頁(yè)面返回到error，服務(wù)降級(jí)成功。

RateLimiter

RateLimiter作為一個(gè)限流工具，主要用于服務(wù)端，用來(lái)保護(hù)接口

在provider中添加resilience4j依賴

        <dependency>
            <groupId>io.github.resilience4j</groupId>
            <artifactId>resilience4j-spring-boot2</artifactId>
            <version>1.2.0</version>
            <exclusions>
                <exclusion>
                    <groupId>io.github.resilience4j</groupId>
                     <artifactId>resilience4j-circuitbreaker</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>io.github.resilience4j</groupId>
                    <artifactId>resilience4j-bulkhead</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>io.github.resilience4j</groupId>
                    <artifactId>resilience4j-timelimiter</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

在application.properties中配置RateLimiter

resilience4j.ratelimiter.limiters..rlA.limit-for-period=1
resilience4j.ratelimiter.limiters.rlA.limit-refresh-period=1s
resilience4j.ratelimiter.limiters..rlA.timeout-duration=1s

為了查看效果，在provider的接口中打印每個(gè)請(qǐng)求處理時(shí)間。通過(guò)@RateLimiter(name = "rlA")標(biāo)記該接口限流，限流策略為rlA

  @Override
    @RateLimiter(name = "rlA")
    public String hello(){
        String s = "hello cloud" + port;
        System.out.println(new Date());
        return s;
    }

在resilience4j模塊的接口中多次發(fā)送請(qǐng)求進(jìn)行測(cè)試

    public String hello(){
        for (int i = 0; i < 3; i++) {
            restTemplate.getForObject("http://localhost:1113/hello",String.class);
        }
        return "success";
    }

可以看到限流生效

image

。