SpringCloud------熔斷器Hystrix的使用

1.GitHub地址

https://github.com/Netflix/Hystrix

https://github.com/Netflix/Hystrix/wiki

 

官方文檔

https://cloud.spring.io/spring-cloud-static/spring-cloud-netflix/2.2.2.RELEASE/reference/html/#circuit-breaker-spring-cloud-circuit-breaker-with-hystrix

 

2.為什么要用Hystrix?

在一個分布式系統里，一個服務依賴多個服務，可能存在某個服務調用失敗，

比如超時，異常等，如何能保證在一個依賴出問題的情況下，不會導致整體服務失敗，

通過Hystrix就可以解決

 

3.功能

提供熔斷，隔離，Fallback，cache，監控等功能

 

4.熔斷后怎么處理？

出現錯誤后，可以Fallback錯誤的處理信息

 

5.代碼實現

1）添加依賴

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

<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-openfeign</artifactId>
</dependency>

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

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.28</version>
</dependency>

 

 

2）啟動類添加@EnableCircuitBreaker

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@MapperScan("cn.ytheng.order_service")
@EnableFeignClients
@EnableCircuitBreaker
public class OrderServiceApplication {

    public static void main(String[] args) {

        SpringApplication.run(OrderServiceApplication.class, args);
    }

}

 

3）添加ProductOrder訂單實體類

import lombok.Data;
import java.io.Serializable;
import java.util.Date;

/**
 * 商品訂單實體類
 */
@Data
public class ProductOrder implements Serializable {
    private String id;
    private int userId;
    private String productName;
    private String tradeNo;
    private Date createTime;

    public ProductOrder() {
    }

}

 

4）添加feign，為了測試Product服務掛掉時，降級處理的情況

import cn.theng.order_service.fallback.ProductFallback;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;

/**
 *
 * 商品服務客戶端
 * product-service: 調用服務名稱，即spring.application.name
 * ProductFallback：需要繼承當前FeignClient的類
 *
 */
@FeignClient(name = "product-service", fallback = ProductFallback.class)
public interface ProductClient {

    @GetMapping("/api/v1/product/find")
    String getById(@RequestParam("id") int id);

}

 

5）添加針對product-service服務的降級處理類

import cn.theng.order_service.service.ProductClient;
import org.springframework.stereotype.Component;

/**
 *
 * 針對商品服務，做降級處理
 *
 */
@Component
public class ProductFallback implements ProductClient {

    //當調用product-service的getById接口出現錯誤時，就會執行該方法
    @Override
    public String getById(int id) {

        System.out.println("feign 調用product-service服務異常...");

        return "null";
    }
}

 

6)添加ProductOrderService接口

import cn.theng.order_service.domain.ProductOrder;

/**
 * 訂單業務類
 */
public interface ProductOrderService {

    /**
     * 下單接口
     */
    ProductOrder save(int userId, int productId);

}

 

7）添加ProductOrderServiceImpl接口實現類import cn.theng.order_service.domain.ProductOrder;import cn.theng.order_service.mapper.ProductOrderMapper;

import cn.theng.order_service.service.ProductClient; import cn.theng.order_service.service.ProductOrderService; import com.alibaba.fastjson.JSON; import com.alibaba.fastjson.JSONObject; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import java.util.Date; import java.util.UUID; @Service public class ProductOrderServiceImpl implements ProductOrderService { @Autowired private ProductClient productClient; @Override public ProductOrder save(int userId, int productId) { String data = productClient.getById(productId); 
// 下面代碼會報錯，觸發熔斷
 JSONObject product = JSON.parseObject(data); ProductOrder order = new ProductOrder(); order.setTradeNo(UUID.randomUUID().toString()); order.setProductName(product.getString("productName")); order.setCreateTime(new Date()); return order; } }

 

8）添加controller

package cn.theng.order_service.controller;

import cn.theng.order_service.domain.ProductOrder;
import cn.theng.order_service.service.ProductClient;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.util.HashMap;
import java.util.Map;

@RestController
@RequestMapping("/api/v1/order")
public class ProductOrderController {

    @Autowired
    private ProductOrderService productOrderService;

    @PostMapping("/test2")
    @HystrixCommand(fallbackMethod = "getProductFail")
    public Object test2(@RequestParam("product_id") int productId) {

        //如果test2內有報錯，則會執行getProductFail方法
        ProductOrder order = productOrderService.save(1, productId);

        return "success";
    }

    //方法簽名一定要與上面方法保持一致
    public Object getProductFail(int productId) {
        Map<String, Object> map = new HashMap<>();
        map.put("code", -1);
        map.put("msg", "目前排隊人數過多，請稍后再試...");
        return map;
    }
}

 

9）修改application.yml配置

server:
  port: 8781
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

spring:
  application:
    name: order-service

#設置調用服務超時時間
#product-service為服務名稱，也可以設置為默認值default
#默認配置下，feign的hystrix配置是關閉的
feign:
  hystrix:
    enabled: true
  client:
    config:
      product-service:
        connectTimeout: 5000
        readTimeout: 11000

 

 

10）訪問地址