请求重试

创建springboot项目，选择web、eureka-client依赖，创建完成后添加resilience4j依赖

<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，未配置的功能无法正常使用，所以要将其他组件先从依赖中排除。

新建yml文件，配置retry，并将该服务注册到erueka

resilience4j:
  retry:
    retry-aspect-order: 399 # 表示retry优先级，一般retry优先级高于限流和断路器
    backends:
      retryA:
        maxRetryAttempts: 5 # 重试次数
        waitDuration: 500 # 重试等待时间
        exponentialBackoffMultipliter: 1.1 # 间隔乘数
        retryException:
          - java.lang.RuntimeException
spring:
  application:
    name: resilience4j
server:
  port: 5000
eureka:
  client:
    service-url:
      defaultZone: http://localhost:1111/eureka

新建Service，调用provider中的接口，声明使用重试策略的名称

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

    }
}

最后编写测试接口，进行测试，可以看到方法共执行了五次。

circuitbreaker

现在依赖中删除对circuitbreaker组件的排除

        <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实例

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

在service中添加服务降级的方法，并在@CircuitBreaker注解中声明断路器的策略和服务降级返回的方法。

@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";
    }
}

访问测试接口可以看到页面返回到error，服务降级成功。

RateLimiter

RateLimiter作为一个限流工具，主要用于服务端，用来保护接口

在provider中添加resilience4j依赖

        <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

为了查看效果，在provider的接口中打印每个请求处理时间。通过@RateLimiter(name = "rlA")标记该接口限流，限流策略为rlA

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

在resilience4j模块的接口中多次发送请求进行测试

    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

。