SpringCloud之Feign

时间 2019-11-09

标签 springcloud feign 繁體版

原文原文链接

【前面的话】书接上文，本文的某些知识依赖个人第一篇SpringCLoud的文章：SpringCloud之Eureka，若是没有看过能够先移步去看一下。另外在微服务架构中，业务都会被拆分红一个个独立的服务，服务与服务的通信是基于http restful的。Spring cloud有两种服务调用方式，一种是ribbon+restTemplate，另外一种是feign。上一篇文章已经讲过ribbon+rest这种方式了，这一片博文主要讲feign的应用。java

壹、Feign的简介

Feign是一个声明式的伪Http客户端，它使得写Http客户端变得更简单。使用Feign，只须要建立一个接口并注解。它具备可插拔的注解特性，可以使用Feign 注解和JAX-RS注解。Feign支持可插拔的编码器和解码器。Feign默认集成了Ribbon，并和Eureka结合，默认实现了负载均衡的效果。git

简而言之：github

Feign 采用的是基于接口的注解
Feign 整合了ribbon

贰、准备工做

新建一个feign子工程lovin-feign-client，用于后面的操做。下面是主要的pom依赖:~~~pom lovincloud com.eelve.lovincloud 1.0-SNAPSHOT 4.0.0 web

<artifactId>lovin-feign-client</artifactId>
    <version>0.0.1</version>
    <name>lovinfeignclient</name>
    <description>feignclient测试</description>复制代码

<dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</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-hystrix</artifactId>
            <version>1.4.7.RELEASE</version>
        </dependency>
    </dependencies>复制代码

<build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
~~~
- 这里为了安全，我这里仍是添加**spring-boot-starter-security**
~~~yaml
server:
  port: 8806   # 服务端口号
spring:
  application:
    name: lovinfeignclient     # 服务名称
  security:
    basic:
      enabled: true
    user:
      name: lovin
      password: ${REGISTRY_SERVER_PASSWORD:lovin}
eureka:
  client:
    serviceUrl:
      defaultZone: http://lovin:lovin@localhost:8881/eureka/   # 注册到的eureka服务地址
feign:
  hystrix:
    enabled: true
~~~
- 配置**spring-boot-starter-security**，这里为了方便我这里放开全部请求
~~~java
package com.eelve.lovin.config;复制代码

import org.springframework.context.annotation.Configuration;import org.springframework.security.config.annotation.web.builders.HttpSecurity;import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;spring

/**安全

@ClassName SecurityConfig
@Description TDO
@Author zhao.zhilue
@Date 2019/8/16 14:13
@Version 1.0
**/
@Configuration
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {

@Override
    protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests().anyRequest().permitAll()
                .and().csrf().disable();
    }
}
~~~
- 在主类上添加**@EnableFeignClients**和**@EnableHystrix** ，固然也须要注册到注册中心：
~~~java
package com.eelve.lovin;复制代码

import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cloud.client.discovery.EnableDiscoveryClient;import org.springframework.cloud.netflix.hystrix.EnableHystrix;import org.springframework.cloud.openfeign.EnableFeignClients;restful

/**网络

@ClassName LovinFeignClientApplication
@Description TDO
@Author zhao.zhilue
@Date 2019/8/15 17:17
@Version 1.0
**/
@SpringBootApplication
@EnableFeignClients
@EnableDiscoveryClient
@EnableHystrix
public class LovinFeignClientApplication {
public static void main(String[] args) {
SpringApplication.run(LovinFeignClientApplication.class,args);
}
}
~~~
- 添加一个远程调用的服务端FeignRemoteService，而且配置feign调用信息：
  ~~~java
  package com.eelve.lovin.service;

import com.eelve.lovin.hystrix.FeignRemoteServiceImpl;import org.springframework.cloud.openfeign.FeignClient;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;架构

/**app

@ClassName FeignRemoteService
@Description TDO
@Author zhao.zhilue
@Date 2019/8/15 17:18
@Version 1.0
**/
@FeignClient(value = "lovineurkaclient",fallback = FeignRemoteServiceImpl.class)
public interface FeignRemoteService {

@RequestMapping(value = "/hello",method = RequestMethod.GET)
    public String hello();
}
~~~
- 添加熔断器调用方法：新建**FeignRemoteServiceImpl**实现**FeignRemoteService**接口：
~~~java
package com.eelve.lovin.hystrix;复制代码

import com.eelve.lovin.service.FeignRemoteService;import org.springframework.stereotype.Component;

/**

@ClassName FeignRemoteServiceImpl
@Description TDO
@Author zhao.zhilue
@Date 2019/8/15 17:31
@Version 1.0
**/
@Component
public class FeignRemoteServiceImpl implements FeignRemoteService {
@Override
public String hello() {
return "hystrix起做用了";
}
}
~~~
- 最后新建FeignController，来消费服务：
  ~~~java
  package com.eelve.lovin.controller;

import com.eelve.lovin.service.FeignRemoteService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.bind.annotation.RestController;

/**

@ClassName FeignController
@Description TDO
@Author zhao.zhilue
@Date 2019/8/15 17:21
@Version 1.0
**/
@RestController
public class FeignController {

@Autowired
    FeignRemoteService feignRemoteService;复制代码

@GetMapping(value = "/getHello")
    public String getHello() {
        return feignRemoteService.hello();
    }
}
~~~
# 叁、启动测试
- 依次启动eureka的服务端和两个客户端，以及新建的lovin-feign-client
![咱们能够看到服务已经所有启动成功](https://i.loli.net/2019/08/23/oJn64HIfmOiVgEP.png)
咱们能够看到服务已经所有启动成功
- 而后访问http://localhost:8806/getHello
![咱们能够看到已经能够经过feign调到咱们创建的eureka客户端了](https://user-gold-cdn.xitu.io/2019/9/4/16cfaf6c1ae610eb?w=1334&h=989&f=png&s=32240)
咱们能够看到已经能够经过feign调到咱们创建的eureka客户端了
- 再次请求接口观察返回
![咱们能够看到咱们调到了经过feign调用ribbon负载的另一个接口](https://user-gold-cdn.xitu.io/2019/9/4/16cfaf6c53bbbed1?w=1333&h=833&f=png&s=28951)
咱们能够看到咱们调到了经过feign调用ribbon负载的另一个接口了，到这里咱们就已经弄好了一个简单的ribbon负载。复制代码

肆、添加Hystrix Dashboard断路器监控

添加须要的pom依赖
~~~pom

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

org.springframework.cloud
spring-cloud-starter-netflix-hystrix-dashboard
2.1.2.RELEASE

~~~
在主类上添加@EnableHystrixDashboard，开启断路器监控，而且配置HystrixMetricsStreamServlet
~~~java
package com.eelve.lovin;

import com.netflix.hystrix.contrib.metrics.eventstream.HystrixMetricsStreamServlet;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.boot.web.servlet.ServletRegistrationBean;import org.springframework.cloud.client.discovery.EnableDiscoveryClient;import org.springframework.cloud.netflix.hystrix.EnableHystrix;import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;import org.springframework.cloud.openfeign.EnableFeignClients;import org.springframework.context.annotation.Bean;

/**

@ClassName LovinFeignClientApplication
@Description TDO
@Author zhao.zhilue
@Date 2019/8/15 17:17
@Version 1.0
**/
@SpringBootApplication
@EnableFeignClients
@EnableDiscoveryClient
@EnableHystrix
@EnableHystrixDashboard
public class LovinFeignClientApplication {
public static void main(String[] args) {
SpringApplication.run(LovinFeignClientApplication.class,args);
}

@Bean
    public ServletRegistrationBean getServlet(){
        HystrixMetricsStreamServlet streamServlet = new HystrixMetricsStreamServlet();
        ServletRegistrationBean registrationBean = new ServletRegistrationBean(streamServlet);
        registrationBean.setLoadOnStartup(1);
        registrationBean.addUrlMappings("/actuator/hystrix.stream");
        registrationBean.setName("HystrixMetricsStreamServlet");
        return registrationBean;
    }
}
~~~
- 访问http://localhost:8806/hystrix
![首页](https://user-gold-cdn.xitu.io/2019/9/4/16cfaf6d1f024c44?w=1912&h=992&f=png&s=186857)
这里咱们经过首页能够看到：
~~~
默认的集群监控：经过URL http://turbine-hostname:port/turbine.stream开启，实现对默认集群的监控。
指定的集群监控：经过URL http://turbine-hostname:port/turbine.stream?cluster=[clusterName]开启，实现对clusterName的监控。
单体应用监控：经过URL http://hystrix-app:port/hystrix.stream开启，实现对某个具体的服务监控
~~~
- 添加监控模式查看详情，这里选择第三个单体应用复制代码

这样咱们就完成了熔断器的监控，固然具体含义有待下一步深究。

伍、网络架构

咱们能够看到咱们调用的服务再也不是像再上一篇文章中的直接访问对应的服务，而是经过feign的Ribbon的负载均衡的去调用的，并且这里说明一点，Ribbon的默认机制是轮询。

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最后的最后是本博客的源码,欢迎关注这一套SpringCloud的实践