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Hystrix 解析

1. Hystrix 断路器

1.1 微服务宕机时，ribbon 无法转发请求

关闭 user-service 和 order-service。

图片描述：79253124f84b080b945e0bad.jpg

1.2 项目创建

复制 sp06-ribbon 项目至 sp07-hystrix，关闭原项目。

图片描述：a70143563e516277aecf4a5.jpg

1.2.1 pom.xml 修改

添加 Spring Cloud Netlix Hystrix 依赖。

图片描述：b0084b145da1f621b293e5ec.jpg

1.2.2 application.yml 配置

添加 Hystrix 配置，启用断路器。

图片描述：c9014cc5d5d72f5db6b2c56.jpg

1.2.3 主程序注解

使用 @EnableCircuitBreaker 启用断路器。

代码示例：

package cn.tedu.sp07;
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.http.client.SimpleClientHttpRequestFactory;
import org.springframework.web.client.RestTemplate;
@SpringBootApplication
@EnableCircuitBreaker
@EnableDiscoveryClient
public class Sp07HystrixApplication {
    public static void main(String[] args) {
        SpringApplication.run(Sp07HystrixApplication.class, args);
    }
    @LoadBalanced
    @Bean
    public RestTemplate getRestTemplate() {
        SimpleClientHttpRequestFactory f = new SimpleClientHttpRequestFactory();
        f.setConnectTimeout(1000);
        f.setReadTimeout(1000);
        return new RestTemplate(f);
    }
}

1.3 HystrixController 降级方法

添加 @HystrixCommand 注解并实现降级方法。

代码示例：

package cn.tedu.sp07.controller;
import cn.tedu.sp01.pojo.Item;
import cn.tedu.sp01.pojo.Order;
import cn.tedu.sp01.pojo.User;
import cn.tedu.web.util.JsonResult;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;
@RestController
public class HystrixController {
    @Autowired
    private RestTemplate rt;
    @GetMapping("/item-service/{orderId}")
    @HystrixCommand(fallbackMethod = "getItemsFB")
    public JsonResult
   
    
     > getItems(@PathVariable String orderId) {
        return rt.getForObject("http://item-service/{1}", JsonResult.class, orderId);
    }
    @PostMapping("/item-service/decreaseNumber")
    @HystrixCommand(fallbackMethod = "decreaseNumberFB")
    public JsonResult decreaseNumber(@RequestBody List
     
       items) {
        return rt.postForObject("http://item-service/decreaseNumber", items, JsonResult.class);
    }
    @GetMapping("/user-service/{userId}")
    @HystrixCommand(fallbackMethod = "getUserFB")
    public JsonResult
      
        getUser(@PathVariable Integer userId) {
        return rt.getForObject("http://user-service/{1}", JsonResult.class, userId);
    }
    @GetMapping("/user-service/{userId}/score")
    @HystrixCommand(fallbackMethod = "addScoreFB")
    public JsonResult addScore(@PathVariable Integer userId, Integer score) {
        return rt.getForObject("http://user-service/{1}/score?score={2}", Paginator.class, userId, score);
    }
    @GetMapping("/order-service/{orderId}")
    @HystrixCommand(fallbackMethod = "getOrderFB")
    public JsonResult
       
         getOrder(@PathVariable String orderId) {
        return rt.getForObject("http://order-service/{1}", Paginator.class, orderId);
    }
    @GetMapping("/order-service")
    @HystrixCommand(fallbackMethod = "addOrderFB")
    public JsonResult addOrder() {
        return rt.getForObject("http://order-service/", Paginator.class);
    }
    @HystrixCommand(fallbackMethod = "getItemsFB")
    public JsonResult getItemsFB(String orderId) {
        return JsonResult.err().msg("获取订单商品列表失败");
    }
    @HystrixCommand(fallbackMethod = "decreaseNumberFB")
    public JsonResult decreaseNumberFB(List
        
          items) { return JsonResult.err().msg("更新商品库存失败"); } @HystrixCommand(fallbackMethod = "getUserFB") public JsonResult getUserFB(Integer userId) { return JsonResult.err().msg("获取用户信息失败"); } @HystrixCommand(fallbackMethod = "addScoreFB") public JsonResult addScoreFB(Integer userId, Integer score) { return JsonResult.err().msg("增加用户积分失败"); } @HystrixCommand(fallbackMethod = "getOrderFB") public JsonResult getOrderFB(String orderId) { return JsonResult.err().msg("获取订单失败"); } @HystrixCommand(fallbackMethod = "addOrderFB") public JsonResult addOrderFB() { return JsonResult.err().msg("添加订单失败"); } }
        
       
      
     
    
   

1.4 Hystrix 超时设置

默认超时为1000ms，建议设置为10秒。

代码示例：

spring:
  application:
    name: hystrix
    server:
      port: 3001
  eureka:
    client:
      service-url:
        defaultZone: http://eureka1:2001/eureka, http://eureka2:2002/eureka
      ribbon:
        MaxAutoRetriesNextServer: 2
        MaxAutoRetries: 1
        OkToRetryOnAllOperations: true
  hystrix:
    command:
      default:
        execution:
          isolation:
            thread:
              timeoutInMilliseconds: 500

1.5 访问测试

• 检查 item-service 超时失败。
• 检查 user-service 未启动。
• 观察断路器状态。

图片描述：多个断路器测试图示。

2. Hystrix 电路板仪表盘

2.1 项目添加 Actuator

添加 Actuator 依赖并配置暴露端点。

代码示例：

   
    
    
     org.springframework.boot
    
    
    
     spring-boot-starter-actuator
    
   

2.1.1 application.yml 配置

暴露 hystrix.stream 端点。

代码示例：

spring:
  application:
    name: hystrix
    server:
      port: 3002
  eureka:
    client:
      service-url:
        defaultZone: http://eureka1:2001/eureka, http://eureka2:2002/eureka
      ribbon:
        MaxAutoRetriesNextServer: 1
        MaxAutoRetries: 1
        OkToRetryOnAllOperations: true
  hystrix:
    command:
      default:
        execution:
          isolation:
            thread:
              timeoutInMilliseconds: 500
  management:
    endpoints:
      web:
        exposure:
          include: hystrix.stream

2.2 Hystrix 仪表盘

独立搭建仪表盘项目，配置监控路径。

代码示例：

package cn.tedu.sp08;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;
@SpringBootApplication
@EnableHystrixDashboard
public class Sp08HystrixDashboardApplication {
    public static void main(String[] args) {
        SpringApplication.run(Sp08HystrixDashboardApplication.class, args);
    }
}

2.3 测试

通过 ab 工具进行高并发测试，观察断路器状态。

命令示例：

ab -n 20000 -c 50 http://localhost:3002/item-service/35

2.4 Hystrix 配置

调整配置参数以优化系统响应。

常用配置：

• hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds
• hystrix.command.default.circuitBreaker.requestVolumeThreshold
• hystrix.command.default.circuitBreaker.errorThresholdPercentage
• hystrix.command.default.circuitBreaker.sleepWindowInMilliseconds

完整文档：Hystrix官方文档