1、介绍

Spring Cloud Circuit breaker provides an abstraction across different circuit breaker implementations. It provides a consistent API to use in your applications allowing you the developer to choose the circuit breaker implementation that best fits your needs for your app.

Spring Cloud断路器提供了一个跨不同断路器的抽象实现。它提供了在您的应用程序中使用的一致的API，允许您的开发人员选择最适合您的应用程序需要的断路器实现。

支持断路器实现有以下几种

Netfix Hystrix (Spring Cloud官方已经不予支持)
Resilience4J （支持）
Sentinel
Spring Retry

2、快速开始

pom.xml

maven依赖配置文件，如下：

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <parent>

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

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

        <version>2.6.4</version>

        <relativePath/> <!-- lookup parent from repository -->

    </parent>

    <groupId>com.mindasoft</groupId>

    <artifactId>spring-cloud-circuitbreaker-consumer</artifactId>

    <version>0.0.1-SNAPSHOT</version>

    <name>spring-cloud-circuitbreaker-consumer</name>

    <description>Demo project for Spring Boot</description>

    <properties>

        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>

        <java.version>1.8</java.version>

        <spring-cloud.version>2021.0.1</spring-cloud.version>

    </properties>

    <dependencies>

        <dependency>

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

            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>

        </dependency>

        <dependency>

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

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

        </dependency>

        <dependency>

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

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

        </dependency>

        <dependency>

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

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

            <scope>test</scope>

        </dependency>

    </dependencies>

    <dependencyManagement>

        <dependencies>

            <dependency>

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

                <artifactId>spring-cloud-dependencies</artifactId>

                <version>${spring-cloud.version}</version>

                <type>pom</type>

                <scope>import</scope>

            </dependency>

        </dependencies>

    </dependencyManagement>

    <build>

        <plugins>

            <plugin>

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

                <artifactId>spring-boot-maven-plugin</artifactId>

            </plugin>

        </plugins>

    </build>

    <repositories>

        <repository>

            <id>nexus-aliyun</id>

            <name>Nexus aliyun</name>

            <url>https://maven.aliyun.com/repository/public</url>

            <layout>default</layout>

            <snapshots>

                <enabled>false</enabled>

            </snapshots>

            <releases>

                <enabled>true</enabled>

            </releases>

        </repository>

    </repositories>

    <pluginRepositories>

        <pluginRepository>

            <id>nexus-aliyun</id>

            <name>Nexus aliyun</name>

            <url>https://maven.aliyun.com/repository/public</url>

            <snapshots>

                <enabled>false</enabled>

            </snapshots>

            <releases>

                <enabled>true</enabled>

            </releases>

        </pluginRepository>

    </pluginRepositories>

</project>

比上个项目多了如下配置：

  <dependency>

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

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

        </dependency>

使用resilience4j 实现断路器。

application.properties

server.port=9004

# 服务注册中心地址

eureka.client.service-url.defaultZone=http://localhost:9000/eureka/

# 服务名称

spring.application.name=circuitbreaker-customer

SpringCloudCircuitBreakerConsumerApplication

package com.mindasoft;

import io.github.resilience4j.circuitbreaker.CircuitBreakerConfig;

import io.github.resilience4j.timelimiter.TimeLimiterConfig;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.cloud.circuitbreaker.resilience4j.Resilience4JCircuitBreakerFactory;

import org.springframework.cloud.circuitbreaker.resilience4j.Resilience4JConfigBuilder;

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

import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;

import org.springframework.context.annotation.Bean;

import org.springframework.web.client.RestTemplate;

import java.time.Duration;

@EnableDiscoveryClient // Eureka Discovery Client 标识

@SpringBootApplication

public class SpringCloudCircuitBreakerConsumerApplication {

    // 开启负载均衡的功能

    @Bean

    @LoadBalanced

    RestTemplate restTemplate() {

        return new RestTemplate();

    }

    @Bean

    public Customizer<Resilience4JCircuitBreakerFactory> defaultCustomizer() {

        return factory -> factory.configureDefault(id -> new Resilience4JConfigBuilder(id)

                .timeLimiterConfig(TimeLimiterConfig.custom().timeoutDuration(Duration.ofSeconds(3)).build())

                .circuitBreakerConfig(CircuitBreakerConfig.ofDefaults())

                .build());

    }

    public static void main(String[] args) {

        SpringApplication.run(SpringCloudCircuitBreakerConsumerApplication.class, args);

    }

}

ConsumerController

package com.mindasoft.consumer;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import org.springframework.beans.factory.annotation.Autowired;

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

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

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

import org.springframework.web.client.RestTemplate;

/**

 * Created by huangmin on 2017/11/10 14:50.

 */

@RestController

public class ConsumerController {

    private static final Logger LOGGER = LoggerFactory.getLogger(ConsumerController.class);

    @Autowired

    private RestTemplate restTemplate; // HTTP 访问操作类

    @Autowired

    private CircuitBreakerFactory circuitBreakerFactory;

    @RequestMapping("/hello")

    public String hello() {

        String providerMsg = circuitBreakerFactory.create("hello")

                .run(() -> restTemplate.getForObject("http://PROVIDER-SERVICE/hello", String.class),

                        throwable -> "CircuitBreaker fallback msg");

        return "Hello,I'm Customer! msg from provider : <br/><br/> " + providerMsg;

    }

}

启动eureka server和本项目，访问http://127.0.0.1:9004/hello

页面打印如下：

Hello,I'm Customer! msg from provider :

CircuitBreaker fallback msg

说明进入到了断路throwable 处理逻辑。

巴特西

06-CircuitBreaker断路器

1、介绍

2、快速开始

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