原创

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