SpringCloud梳理-Feign

BolunWu

1.Feign

为服务应用中,ribbon和hystrix同时出现,feign整合两者,并提供了声明式消费者客户端.
feign是一种集成工具功能有:远程调用,ribbon-负载均衡和重试,hystrix-降级 熔断

1.1Feign远程调用

Fegin提供了声明式客户端,只需要定义一个接口,就可以通过接口做远程调用.具体调用代码通过动态代理添加.
// 调用商品服务的远程调用接口

// 通过注解配置3件事:调用哪个服务,调用什么路径,向这个路径提交什么参数

@FeignClient(name="item-service")

public interface ItemFeignClient {

 @GetMapping("/{orderId}")

 JsonResult<List<Item>> getItems(@PathVariable String orderId);

}

1.1.1添加声明式客户端

1.OpenFegin依赖
2.启动类添加@EnableFeignClient
3.定义声明式客户端接口 例如:ItemFeignClient UserFeignClient OrderFeignClient
4.添加一个测试用的控制器,使用三个声明式客户端接口调用远程服务.

1.2Feign集成Ribbon

负载均衡 重试
Feign默认启用了Ribbon的负载均衡和重试 0配置.
默认重试参数:MaxAutoRetries=0 MaxAutoRetriesNextServer=1 ReadTimeout=1000
重试参数配置
# 对所有服务都有效

ribbon:

 MaxAutoRetries: 1

# 对 item-service 单独配置,对其他服务无效

item-service:

 ribbon: 

 MaxAutoRetries: 0

1.3Feign集成Hystrix

默认不启用hystrix,Feign不推荐启用hystrix

1.3.1如果有特殊需求要启用hystrix,首先做基础配置

1.添加hystrix完整依赖
2.添加@EnableCircuitBreaker
3.yml配置feign.hystrix.enable=true

1.3.2降级

在声明式客户端接口的注解中,制定一个降级类(之前的是降级方法)
@FeignClient(name="item-service", fallback=降级类.class)

public interface ItemFeignClient {

 ....

}
降级类要作为声明式客户端接口的子类来定义.

1.3.3hystrix监控

用actuator暴露hystrix.stream监控端点
1.actuator依赖
2.暴露监控端点
m.e.w.e.i=hystrix.stream
3.http://localhost:3001/actuator/hystrix.stream
4.通过调用后台服务,产生监控数据.

1.4熔断

10秒内20次请求,50%失败执行了降级代码.

2.代码展示

用feign代替hystrix+ribbon

image

2.1新建fegin项目

image

image

2.2pom.xml文件

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>cn.tedu</groupId>
    <artifactId>sp09-feign</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>sp09-feign</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Hoxton.RELEASE</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <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.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

2.3application.yml

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

2.4主程序添加@EnableDiscoveryClient和@EnableFeignClients注解

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;

@EnableFeignClients
@EnableDiscoveryClient
@SpringBootApplication
public class Sp09FeignApplication {

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

}

2.5.1 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<List<Item>> getItems(@PathVariable String orderId);

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

2.5.2 UserFeignService

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<User> 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);
}

2.5.3 UserFeignService

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<Order> getOrder(@PathVariable String orderId);

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

}

2.5.4 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<List<Item>> getItems(@PathVariable String orderId) {
        return itemService.getItems(orderId);
    }

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

    /
    
    @GetMapping("/user-service/{userId}")
    public JsonResult<User> 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<Order> getOrder(@PathVariable String orderId) {
        return orderService.getOrder(orderId);
    }

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

2.6调用流程

image

2.7启动服务并测试

image

http://eureka1:2001

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/

源码: https://github.com/benwang6/spring-cloud-repo

3.Feign+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

3.1application.yml配置ribbon超时和重试

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
  
item-service:
  ribbon:
    MaxAutoRetries: 1
    MaxAutoRetriesNextServer: 2
    ConnectTimeout: 1000
    ReadTimeout: 500

3.2启动服务,访问测试

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

4.Feign+hystrix降级

feign默认没有启用hystrix,添加配置,启用hystrix

4.1application.yml配置

feign:
  hystrix:
    enabled: true
启用后访问服务器:

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

默认一秒会快速失败,没有降级方法,会显示白半页.

image

可以添加配置暂时减少降级超时时间,以便后续对降级进行测试
......

feign:
  hystrix:
    enabled: true
    
hystrix:
  command:
    default:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds: 500

4.feign+hystrix降级

4.1feign远程接口中指定降级类

远程调用失败后会执行降级代码

4.2指定降级类

4.2.1 ItemFeignService

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

4.2.2UserFeignService

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

4.2.3OrderFeignService

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

4.3降级类

4.3.1 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<List<Item>> getItems(String orderId) {
        return JsonResult.err("无法获取订单商品列表");
    }

    @Override
    public JsonResult decreaseNumber(List<Item> items) {
        return JsonResult.err("无法修改商品库存");
    }

}

4.3.2UserFeignServiceFB

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<User> getUser(Integer userId) {
        return JsonResult.err("无法获取用户信息");
    }

    @Override
    public JsonResult addScore(Integer userId, Integer score) {
        return JsonResult.err("无法增加用户积分");
    }

}

4.3.3 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<Order> getOrder(String orderId) {
        return JsonResult.err("无法获取商品订单");
    }

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

}

4.4启动服务,访问测试

image

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