微服务springcloud 06.feign框架，配合ribbon 负载均衡和重试，配合hystrix 降级，监控和熔断测试

feign是ribbon +hystrix 的整合
01.新建 sp09-feign 项目
第一步：

第二步：选择依赖：

pom.xml
需要添加 sp01-commons 依赖：

	4.0.0
	
		org.springframework.boot
		spring-boot-starter-parent
		2.3.1.RELEASE
		 
	
	cn.tedu
	sp09-feign
	0.0.1-SNAPSHOT
	sp09-feign
	Demo project for Spring Boot
	
		1.8
		Hoxton.SR12
	
	
		
			org.springframework.boot
			spring-boot-starter-actuator
		
		
			org.springframework.boot
			spring-boot-starter-web
		
		
			org.springframework.cloud
			spring-cloud-starter-netflix-eureka-client
		
		
			org.springframework.cloud
			spring-cloud-starter-openfeign
		

		
			org.springframework.boot
			spring-boot-starter-test
			test
			
				
					org.junit.vintage
					junit-vintage-engine
				
			
		
		
			cn.tedu
			sp01-commons
			0.0.1-SNAPSHOT
		
	
	
		
			
				org.springframework.cloud
				spring-cloud-dependencies
				${spring-cloud.version}
				pom
				import
			
		
	

	
		
			
				org.springframework.boot
				spring-boot-maven-plugin
			
		
	

第三步：修改sp09-feign项目的application.yml

spring:
  application:
    name: feign
    
server:
  port: 3001
  
eureka:
  client:
    service-url:
      defaultZone: http://eureka1:2001/eureka, http://eureka2:2002/eureka

第四步：sp09-feign的主程序添加 @EnableDiscoveryClient 和 @EnableFeignClients

package cn.tedu.sp09;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

@EnableDiscoveryClient
@EnableFeignClients
@SpringBootApplication
public class Sp09FeignApplication {

	public static void main(String[] args) {
		SpringApplication.run(Sp09FeignApplication.class, args);
	}

}

02.feign 声明式客户端

feign 利用了我们熟悉的 spring mvc 注解来对接口方法进行设置，降低了我们的学习成本。
通过这些设置,feign可以拼接后台服务的访问路径和提交的参数

例如：

@GetMapping("/{userId}/score") 
JsonResult addScore(@PathVariable Integer userId, @RequestParam Integer score);

当这样调用该方法：

service.addScore(7, 100);

那么 feign 会向服务器发送请求：

http://用户微服务/7/score?score=100

注意：如果 score 参数名与变量名不同，需要添加参数名设置：
@GetMapping("/{userId}/score") 
JsonResult addScore(@PathVariable Integer userId, @RequestParam("score") Integer s);

第一步：声明三个代理接口

这里的三个Feign类型service接口，就好像是ribbon中的ribbonController（但是没有注解controller，并不能接受客户端的request请求，所以只是类似），只是调用service中的方法。具体方法的实现还是要在原来的service中去完成。
@FeignClient(“item-service”)，中的item-service是在service服务中的application.yml文件中的spring.application.name来确定的

ItemFeignService：

package cn.tedu.sp09.service;

import java.util.List;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;

import cn.tedu.sp01.pojo.Item;
import cn.tedu.web.util.JsonResult;

@FeignClient("item-service")
public interface ItemFeignService {
	@GetMapping("/{orderId}")
	JsonResult> getItems(@PathVariable String orderId);

	@PostMapping("/decreaseNumber")
	JsonResult decreaseNumber(@RequestBody List items);
}

UserFeignService
注意,如果请求参数名与方法参数名不同,@RequestParam不能省略,并且要指定请求参数名:
@RequestParam(“score”) Integer s

package cn.tedu.sp09.service;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestParam;

import cn.tedu.sp01.pojo.User;
import cn.tedu.web.util.JsonResult;

@FeignClient("user-service")
public interface UserFeignService {
	@GetMapping("/{userId}")
	JsonResult getUser(@PathVariable Integer userId);

    // 拼接路径 /{userId}/score?score=新增积分
	@GetMapping("/{userId}/score") 
	JsonResult addScore(@PathVariable Integer userId, @RequestParam Integer score);
}

OrderFeignService：

package cn.tedu.sp09.service;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

import cn.tedu.sp01.pojo.Order;
import cn.tedu.web.util.JsonResult;

@FeignClient("order-service")
public interface OrderFeignService {
	@GetMapping("/{orderId}")
	JsonResult getOrder(@PathVariable String orderId);

	@GetMapping("/")
	JsonResult addOrder();

}

第二步：编写FeignController，这个是用来接受web请求的，是真正的controller
FeignController：

package cn.tedu.sp09.controller;

import java.util.List;

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

import cn.tedu.sp01.pojo.Item;
import cn.tedu.sp01.pojo.Order;
import cn.tedu.sp01.pojo.User;
import cn.tedu.sp09.service.ItemFeignService;
import cn.tedu.sp09.service.OrderFeignService;
import cn.tedu.sp09.service.UserFeignService;
import cn.tedu.web.util.JsonResult;

@RestController
public class FeignController {
	@Autowired
	private ItemFeignService itemService;
	@Autowired
	private UserFeignService userService;
	@Autowired
	private OrderFeignService orderService;
	
	@GetMapping("/item-service/{orderId}")
	public JsonResult> getItems(@PathVariable String orderId) {
		return itemService.getItems(orderId);
	}

	@PostMapping("/item-service/decreaseNumber")
	public JsonResult decreaseNumber(@RequestBody List items) {
		return itemService.decreaseNumber(items);
	}

	
	@GetMapping("/user-service/{userId}")
	public JsonResult getUser(@PathVariable Integer userId) {
		return userService.getUser(userId);
	}

	@GetMapping("/user-service/{userId}/score") 
	public JsonResult addScore(@PathVariable Integer userId, Integer score) {
		return userService.addScore(userId, score);
	}
	
	
	@GetMapping("/order-service/{orderId}")
	public JsonResult getOrder(@PathVariable String orderId) {
		return orderService.getOrder(orderId);
	}

	@GetMapping("/order-service")
	public JsonResult addOrder() {
		return orderService.addOrder();
	}
}

为什么可以直接在@GetMapping(“/order-service”)中直接写order-service，因为feign有ribbon技术，可以直接调用服务的服务名
调用流程

第三步：启动服务，并访问测试

http://eureka1:2001
http://localhost:3001/item-service/35

http://localhost:3001/item-service/decreaseNumber
使用postman，POST发送以下格式数据：
[{“id”:1, “name”:“abc”, “number”:23},{“id”:2, “name”:“def”, “number”:11}]

http://localhost:3001/user-service/7

http://localhost:3001/user-service/7/score?score=100

http://localhost:3001/order-service/123abc

http://localhost:3001/order-service/

03.配合ribbon 负载均衡和重试
无需额外配置，feign 默认已启用了 ribbon 负载均衡和重试机制。可以通过配置对参数进行调整

重试的默认配置参数:
ConnectTimeout=1000
ReadTimeout=1000
MaxAutoRetries=0
MaxAutoRetriesNextServer=1

第一步：可以在sp09-feign 项目的application.yml 配置 ribbon 超时和重试
ribbon.xxx 全局配置
item-service.ribbon.xxx 对特定服务实例的配置

spring:
  application:
    name: feign
    
server:
  port: 3001
  
eureka:
  client:
    service-url:
      defaultZone: http://eureka1:2001/eureka, http://eureka2:2002/eureka
ribbon:
  ConnectTimeout: 1000
  ReadTimeOut: 1000
  MaxAutoRetries: 1
  MaxAutoRetriesNextServer: 2
item-service:
  ribbon:
    ConnectTimeout: 1000
    ReadTimeOut: 1000
    MaxAutoRetries: 2
    MaxAutoRetriesNextServer: 1

启动服务，访问测试
http://localhost:3001/item-service/35

04.feign + hystrix 降级
feign 启用 hystrix
第一步：feign 默认没有启用 hystrix，添加配置，启用 hystrix
feign.hystrix.enabled=true
application.yml 添加配置

feign:
  hystrix:
    enabled: true

第二步：降级类
降级类需要实现远程接口
ItemFeignServiceFB

package cn.tedu.sp09.service;

import java.util.List;
import org.springframework.stereotype.Component;
import cn.tedu.sp01.pojo.Item;
import cn.tedu.web.util.JsonResult;

@Component
public class ItemFeignServiceFB implements ItemFeignService{

	@Override
	public JsonResult> getItems(String orderId) {
		return JsonResult.err("获取订单失败");
	}

	@Override
	public JsonResult decreaseNumber(List items) {
		return JsonResult.err("减少库存失败");
	}
}

UserFeginServiceFB

package cn.tedu.sp09.service;

import org.springframework.stereotype.Component;
import cn.tedu.sp01.pojo.User;
import cn.tedu.web.util.JsonResult;

@Component
public class UserFeignServiceFB implements UserFeignService {

	@Override
	public JsonResult getUser(Integer userId) {
		return JsonResult.err("获取用户失败");
	}

	@Override
	public JsonResult addScore(Integer userId, Integer score) {
		return JsonResult.err("增加积分失败");
	}

}

OrderFeignServiceFB

package cn.tedu.sp09.service;

import org.springframework.stereotype.Component;
import cn.tedu.sp01.pojo.Order;
import cn.tedu.web.util.JsonResult;

@Component
public class OrderFeignServiceFB implements OrderFeignService {

	@Override
	public JsonResult getOrder(String orderId) {
		return JsonResult.err("获取订单失败");
	}

	@Override
	public JsonResult addOrder() {
		return JsonResult.err("保存订单失败");
	}

}

第三步：在代理接口（ItemFeignService）中去声明降级类
远程调用失败, 会执行降级类中的代码，在注解@FeignClient中去添加属性fallback
ItemFeignService

@FeignClient(name="item-service",fallback = ItemFeignServiceFB.class)
public interface ItemFeignService {

UserFeignService

@FeignClient(name="user-service",fallback = UserFeignServiceFB.class)
public interface UserFeignService {

OrderFeignService

@FeignClient(name="order-service",fallback = OrderFeignServiceFB.class)
public interface OrderFeignService {

04.feign + hystrix 监控和熔断测试
第一步：修改sp09-feign项目
pom.xml 添加 hystrix 起步依赖，feign 没有包含完整的 hystrix 依赖
右键点击项目,编辑起步依赖,添加hystrix依赖

	  org.springframework.cloud
	  spring-cloud-starter-netflix-hystrix

第二步：主程序添加 @EnableCircuitBreaker

package cn.tedu.sp09;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.SpringCloudApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

//@EnableCircuitBreaker
//@EnableDiscoveryClient
//@SpringBootApplication
@SpringCloudApplication
@EnableFeignClients
public class Sp09FeignApplication {

	public static void main(String[] args) {
		SpringApplication.run(Sp09FeignApplication.class, args);
	}

}

第三步：sp09-feign 配置 actuator，暴露 hystrix.stream 监控端点
actuator 依赖
查看pom.xml, 确认已经添加了 actuator 依赖

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

application.yml 暴露 hystrix.stream 端点

management:
  endpoints:
    web:
      exposure:
        include: hystrix.stream

第四步：启动服务，查看监控端点
http://localhost:3001/actuator

第五步：启动hystrix dashboard
启动 hystrix dashboard 服务，填入feign监控路径，开启监控
访问 http://localhost:4001/hystrix

在其中填入 feign 监控路径:
http://localhost:3001/actuator/hystrix.stream

访问微服务，以产生监控数据

http://localhost:3001/item-service/35

http://localhost:3001/user-service/7
http://localhost:3001/user-service/7/score?score=100

http://localhost:3001/order-service/123abc
http://localhost:3001/order-service/

第六步：熔断测试
用ab工具，以并发50次，来发送20000个请求

ab -n 20000 -c 50 http://localhost:3001/item-service/35

断路器状态为 Open，所有请求会被短路，直接降级执行fallback方法