SpringCloud 负载均衡Ribbon 和 声明式服务调用Feign

一、ribbon的介绍

    1、什么是ribbon？

ribbon是基于netflix ribbon实现的一个工作在consumer端的负载均衡工具，提供了很多负载均衡策略：轮询、随机

1.1 随机策略

com.netflix.loadbalancer.RandomRule：该策略实现了从服务清单中随机选择一个服务实例的功能。

1.2轮询策略

com.netflix.loadbalancer.RoundRobinRule：该策略实现按照线性轮询的方式依次选择实例的功能。具体实现如下，在循环中增加了一个count计数变量，该变量会在每次轮询之后累加并求余服务总数

2、ribbon的启动器

nacos已经集成了ribbon，故无启动器

二、ribbon的入门案例

1、开启ribbon

@Bean
/**
* 原理：
*  ①拦截器---------"ribbon-provider"----------->List<Service> serviceList
*  ②使用ribbon的负载均衡算法-------------serviceList-------------->Service.
*  ③把url中的map的key替换为ip、port
*/

package com.hg.config;import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;@Configuration
public class ConfigBean {@Bean/***  LoadBalanced工作原理：*  1、ribbon会给RestTemplate添加拦截器,在拦截器中使用“ribbon-provider”获得*  List<ServiceInstance>*  2、再使用负载均衡算法获得一个ServiceInstance*  3、最后通过ServiceInstance把url中的“ribbon-provider”替换成ip和port*///@LoadBalanced //开启负载均衡public RestTemplate getRestTemplate(){return new RestTemplate();}//随机策略@Beanpublic IRule iRule() {return new RandomRule();}
}

    2、调用provider

        //把ip和port换成map的key
String url = "http://ribbon-provider/provider/getUserById/"+id;

package com.hg.controller;import com.hg.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;import java.util.List;
import java.util.Random;@RestController
@RequestMapping(value = "/consumer")
public class ConsumerController {@Autowiredprivate RestTemplate restTemplate;@RequestMapping(value = "/getUserById/{id}")public User getUserById(@PathVariable Integer id) {//不使用ribbon：ip:port//String serviceUrl = "127.0.0.1:9090";//使用ribbon：不再使用ip:port的方式，而是改成了serviceId(即Nacos中注册的服务名称)String serviceUrl = "ribbon-provider";return restTemplate.getForObject("http://" + serviceUrl + "/provider/getUserById/" + id, User.class);}
}

3、指定负载均衡策略

        @Beanpublic IRule iRule(){return new RandomRule();}

三、ribbon的问题

  手动拼接url和参数显得好傻

---------------------------声明式服务调用Feign---------------------------

一、Feign的介绍

1、什么是Feign？

        feign是springcloud提供的声明式模板化(接口)的http客户端(工作在consumer端口)

        feign支持springmvc注解

        feign集成了ribbon也支持负载均衡

      feign = RestTemplate + ribbon

    2、feign的启动器

        spring-cloud-starter-openfeign

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

二、Feign的入门案例

    1、创建feign_provider

 拷贝ribbon_provider_1

2、创建feign_interface

        1)pom.xml

            spring-cloud-starter-openfeign
springcloud_common

<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
<dependency><groupId>com.hg</groupId><artifactId>springcloud_common</artifactId><version>1.0-SNAPSHOT</version>
</dependency>

        2)feign接口

           package com.hg.feign;

            @FeignClient("map的key")@RequestMapping("/provider")public interface UserFeign{@RequestMapping("/getUserById/{id}")public User getUserById(@PathVariable("id") Integer id);}

    3、创建feign_consumer

1)拷贝ribbon_consumer

     2)pom.xml

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd"><parent><artifactId>springcloud_parent</artifactId><groupId>com.hg</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>ribbon_consumer</artifactId><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>com.hg</groupId><artifactId>springcloud_common</artifactId><version>1.0-SNAPSHOT</version></dependency><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency><!--feign接口--><dependency><groupId>com.hg</groupId><artifactId>feign_interface</artifactId><version>1.0-SNAPSHOT</version></dependency></dependencies>
</project>

        3)controller

package com.hg.controller;import com.hg.feign.UserFeign;
import com.hg.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;import java.util.List;
import java.util.Random;@RestController
@RequestMapping(value = "/consumer")
public class ConsumerController {@Autowiredprivate UserFeign userFeign;@RequestMapping(value = "/getUserById/{id}")public User getUserById(@PathVariable Integer id) {return userFeign.getUserById(id);}
}

        4)app

package com.hg;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;@SpringBootApplication
@EnableDiscoveryClient
//@EnableFeignClients(basePackages = "com.hg.feign")
@EnableFeignClients//开启feign接口扫描
public class ConsumerApp {public static void main(String[] args) {SpringApplication.run(ConsumerApp.class);}
}

三、feign的工作原理

    1、扫描feign接口

        @EnableFeignClients开启feign注解的支持：FeignClientsRegistrar.registerFeignClients()扫描添加了@FeignClient注解 的接口，并生成代理类交给spring的ioc容器去管理

    2、代理类做的事

        SynchronousMethodHandler.invoke()：创建RequestTemplate(HttpMethod、UriTemplate、Body)

四、feign的传参方式

1、restful参数

        @PathVariable("id")   //例如：/getUserById/520

 2、？传参

        @RequestParam("id")   //例如：/updateUserById?id=520

3、pojo

        @RequestBody   //例如：{id:250, name:"刘亦菲", age:18}

五、feign优化

    1、开启feign的日志

        logging:
level:
com.hg.feign: debug #log4j的日志级别，“com.hg.feign”feign的包名
feign:
client:
config:
default:
#feign-provider:
loggerLevel: full #开启feign的日志

  2、GZIP压缩

        ①开启浏览器和consumer之间的压缩

            server:
compression:
enabled: true #开启浏览器--->consumer的gzip压缩

        ②开启consumer和provider之间的压缩

            feign:
compression:
request:
enabled: true #开启consumer--->provider的gzip压缩
response:
enabled: true

    3、http连接池

        <dependency>
<groupId>io.github.openfeign</groupId>
<artifactId>feign-httpclient</artifactId>
</dependency>

    4、负载均衡

        @Configurationpublic class FeignConfig {@Beanpublic IRule iRule(){return new WeightedResponseTimeRule();}}

    5、feign超时

        方式一：

            ribbon:
ReadTimeout: 5000 # 请求连接的超时时间
ConnectionTimeout: 5000 # 请求处理的超时时间

        方式二：

            feign:
client:
config:
#default:
feign-provider:
ConnectTimeout: 5000 # 请求连接的超时时间
ReadTimeout: 5000 # 请求处理的超时时间