引入父类的依赖

<?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">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.parent</groupId>
    <artifactId>springdloud-parent</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>hystrix-service</module>
    </modules>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
    </parent>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Greenwich.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
                <version>2.1.6.RELEASE</version>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
                <version>2.2.9.RELEASE</version>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
                <version>2.5.4</version>
            </dependency>
        </dependencies>
    </dependencyManagement>


</project>

引入子类依赖

<?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>
        <artifactId>springdloud-parent</artifactId>
        <groupId>com.parent</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.hystrix</groupId>
    <artifactId>hystrix-service</artifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>


</project>

引入完整代码

package com.hystrix;

import org.springframework.boot.SpringApplication;
import org.springframework.cloud.client.SpringCloudApplication;

@SpringCloudApplication //这个注解包含了多个注解
public class HystrixApplication {
    public static void main(String[] args) {
        SpringApplication.run(HystrixApplication.class,args);
    }
}


package com.hystrix.controller.front;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HystrixController {

    @GetMapping("/hystrixTest/{id}")
    @HystrixCommand(
            commandProperties = {
                   @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",value = "3000")
            },
            fallbackMethod = "returnDefaultResult"
    )
    public String hystrixTest(@PathVariable String id){
        try {
            Thread.sleep(4000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "返回值:"+id;
    }


    public String returnDefaultResult(@PathVariable String id){

        return "恭喜您调用的服务去火星了，"+id+"找不到了";
    }
}

本地熔断器超时设置的3秒钟，程序设置运行的是4秒钟

浏览器输入http://127.0.0.1:8080/hystrixTest/1992

显示如下

这就代表熔断了