熔断器:
1.创建项目
2.在pom.xml中加入依赖：
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-eureka</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-hystrix</artifactId> </dependency>3.配置yml文件：
server: port: 8030 eureka: instance: #定义Eureka实例 hostname: localhost #Eureka实例所在的主机名 prefer-ip-address: true client: service-url: defaultZone: http://localhost:8761/eureka/ spring: application: name: microservice-user-hystrix #名字4.在启动类添加注解开启熔断器功能：@EnableCircuitBreaker
package com.itheima.microserviceuserhystrix; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker; 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; @SpringBootApplication @EnableDiscoveryClient @EnableCircuitBreaker public class MicroserviceUserHystrixApplication { public static void main(String[] args) { SpringApplication.run(MicroserviceUserHystrixApplication.class, args); } @Bean @LoadBalanced public RestTemplate restTemplate() { return new RestTemplate(); } }5.在控制器类添加注解@@HystrixCommand(fallbackMethod = "fallbackinfo")指定回调函数，并添加回调函数：
package com.itheima.microserviceuserhystrix.controller; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RestController; import org.springframework.web.client.RestTemplate; import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand; @RestController public class UserController { @Autowired private RestTemplate restTemplate; //根据用户查找订单 @GetMapping("/findOrderByUser/{id}") @HystrixCommand(fallbackMethod = "fallbackinfo") public String findOrderByUser(@PathVariable String id) { //假设用户只有一个订单，订单id为123 int oid = 123; return this.restTemplate.getForObject("http://microservice-order/1", String.class); } public String fallbackinfo(@PathVariable String id) { return "服务不可用，请稍后再试！"; } }6.启动eureka，order(7900),order(7901),user-hystrix,浏览器访问：
成功显示数据
失败显示回调内容
Hystrix Dashboard使用：
1.在pom.xml加入依赖：
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency>2.6.启动eureka，order(7900),order(7901),user-hystrix,浏览器访问：
http://localhost:8030/findOrderByUser/1
http://localhost:8030/hystrix.stream
在未访问第一个url之前返回都是ping,访问后返回数据：
虽然可以实时监控数据，但是可读性太差，Hystrix Dashboard是Hystrix的一个组件，Hystrix Dashboard提供了数据监控和友好的图形化界面。
1.建立工程microservice-hystrix-dashboard
2.pom.xml增加依赖
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-hystrix-dashboard</artifactId> </dependency>3.修改yml文件：
server: port: 8031 spring: application: name: microservice-hystrix-dashboard #名字4.启动类添加注解：@@EnableHystrixDashboard
package com.itheima.microservicehystrixdashboard; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard; @SpringBootApplication @EnableHystrixDashboard public class MicroserviceHystrixDashboardApplication { public static void main(String[] args) { SpringApplication.run(MicroserviceHystrixDashboardApplication.class, args); } }5.启动，并访问：http://localhost:8031/hystrix.stream
6.增加监控
点击Monitor Stream:
