Spring Boot集成Resilience4J实现断路器功能

1.什么是Resilience4J？

Netflix Hystrix 断路器是 Spring Cloud 中最早就开始支持的一种服务调用容错解决方案，但是目前的 Hystrix 已经处于维护模式了，虽然这并不影响已经上线的项目，并且在短期内，你甚至也可以继续在项目中使用 Hystrix 。但是长远来看，处于维护状态的 Hystrix 走下历史舞台只是一个时间问题，特别是在 Spring Cloud Greenwich 版中，官方已经给出了 Hystrix 的建议替代方案。如下图： 660329-20200912073853847-1594925749

Resilience4j 是 Spring Cloud Greenwich 版推荐的容错解决方案，它是一个轻量级的容错库，受 Netflix Hystrix 的启发而设计，它专为 Java 8 和函数式编程而设计。 Resilience4j 非常轻量级，因为它的库只使用 Vavr （以前称为 Javaslang ），它没有任何其他外部库依赖项。相比之下， Netflix Hystrix 对Archaius 具有编译依赖性，这导致了更多的外部库依赖，例如 Guava 和 Apache Commons 。而如果使用Resilience4j，你无需引用全部依赖，可以根据自己需要的功能引用相关的模块即可。 Resilience4j 也提供了一系列增强微服务可用性的功能，主要功能如下：

断路器
限流
基于信号量的隔离
缓存
限时
请求重试

今天我么主要讲解断路器是如何实现的？

2.实验工程

实验目的

实现断路器功能

pom.xml

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>3.2.1</version> </parent> <modelVersion>4.0.0</modelVersion> <artifactId>resilience4j</artifactId> <properties> <maven.compiler.source>17</maven.compiler.source> <maven.compiler.target>17</maven.compiler.target> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-autoconfigure</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>io.github.resilience4j</groupId> <artifactId>resilience4j-spring-boot3</artifactId> <version>2.0.2</version> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-aop</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency> </dependencies> </project>

controller

package com.et.resilience4j.controller; import com.et.resilience4j.model.Activity; import io.github.resilience4j.circuitbreaker.annotation.CircuitBreaker; import lombok.extern.slf4j.Slf4j; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; import org.springframework.web.client.RestTemplate; @Slf4j @RequestMapping("/activity") @RestController public class ActivityController { private RestTemplate restTemplate; private final String BORED_API = "http://www.liuhaihua.cn/api/activity"; public ActivityController(RestTemplate restTemplate) { this.restTemplate = restTemplate; } @GetMapping @CircuitBreaker(name = "randomActivity", fallbackMethod = "fallbackRandomActivity") public String getRandomActivity() { ResponseEntity<Activity> responseEntity = restTemplate.getForEntity(BORED_API, Activity.class); Activity activity = responseEntity.getBody(); log.info("Activity received: " + activity.getActivity()); return activity.getActivity(); } public String fallbackRandomActivity(Throwable throwable) { return "fail to read a Activity from HBLOG"; } }

entity

package com.et.resilience4j.model; import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; /* sample message { "activity": "Start a family tree", "type": "social", "participants": 1, "price": 0, "link": "https://en.wikipedia.org/wiki/Family_tree", "key": "6825484", "accessibility": 1 }*/ @NoArgsConstructor @AllArgsConstructor @Data public class Activity { private String activity; private String type; private String link; private String key; private Integer participants; private Double price; private Double accessibility; }

DemoApplication.java

package com.et.resilience4j; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.annotation.Bean; import org.springframework.web.client.RestTemplate; @SpringBootApplication public class DemoApplication { public static void main(String[] args) { SpringApplication.run(DemoApplication.class, args); } @Bean public RestTemplate restTemplate() { return new RestTemplate(); } }

application.yaml

spring: application.name: resilience4j-demo jackson.serialization.indent_output: true management: endpoints.web.exposure.include: - '*' endpoint.health.show-details: always health.circuitbreakers.enabled: true resilience4j.circuitbreaker: configs: default: registerHealthIndicator: true slidingWindowSize: 10 minimumNumberOfCalls: 5 permittedNumberOfCallsInHalfOpenState: 3 automaticTransitionFromOpenToHalfOpenEnabled: true waitDurationInOpenState: 5s failureRateThreshold: 50 eventConsumerBufferSize: 10