SpringCloud -- Feign & Hystrix 介绍

The role of these two components is to solve the calls between multiple micro-services, how to solve a call, a call to resolve an error occurred while how to solve

Called before the service can be used more directly to request http request or rest every micro service request

 

 

 

 

 

 Feign when dependent on appname Ribbon can turn ip: port, Fegin is resealed on the Ribbon, such service calls between the micro simpler

 

 

 

 

 Creating a Fegin and Hystrix project

pom.xml file

<Dependencies> 
        <-! introduced Web function -> 
        <dependency> 
            <the groupId> org.springframework.boot </ the groupId> 
            <the artifactId> Starter-Spring-Boot-Web </ the artifactId> 
        </ dependency> 
        <! - 
            Eureka client, when the client registered to Eureka Server will provide a range of metadata information, such as: host, port, and other health checks url 
            Eureka Server accepts heartbeat information for each client sent if a timeout configuration a heartbeat is not received within the time information, examples will be removed from the registration list
         -> 
        <dependency> 
            <the groupId> org.springframework.cloud </ the groupId> 
            <the artifactId> Starter-Spring-Cloud-Netflix-Eureka-Client < / the artifactId> 
        </ dependency> 
        <-! introduced Feign,Can be called micro-services declaratively ->Can be called micro-services declaratively -> 
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <!-- 引入服务容错 Hystrix 的依赖 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <!-- Java Persistence API, ORM 规范 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <!- MySQL driver, note that this requires the corresponding version of MySQL -> 
        <dependency>
            <the groupId> MySQL </ the groupId>
            <the artifactId> MySQL-Connector-Java </ the artifactId> 
            <Version> 5.1.47 </ Version> 
            <scope> Runtime </ scope> 
        </ dependency> 
        <-! Universal Module -> 
        <dependency> 
            <the groupId> COM .imooc.homepage </ the groupId> 
            <the artifactId> Common-Homepage </ the artifactId> 
            <Version> the SNAPSHOT-1.0 </ Version> 
        </ dependency> 
    </ Dependencies> 

    <-! 
        Maven SpringBoot plug, it is possible in a manner Maven to support applications SpringBoot may be 
        SpringBoot applications packaged as an executable jar or war files, and then run the application in the usual way SpringBoot
      -> 
    <Build> 
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

Startup class configuration

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.data.jpa.repository.config.EnableJpaAuditing;

@EnableJpaAuditing
@EnableFeignClients
@EnableCircuitBreaker
@EnableEurekaClient
@SpringBootApplication
public class HomepageUserApplication {
    public static void main(String[] args) {
        SpringApplication.run(HomepageUserApplication.class,args);
    }
}

Configuration application.yml profile

server:
  port: 7000
  servlet:
    context-path: /homepage-user

spring:
  main:
    allow-bean-definition-overriding: true
  application:
    name: eureka-client-homepage-user
  jpa:
    show-sql: true
    hibernate:
      ddl-auto: none
    properties:
      hibernate.format_sql: true
    open-in-view: false
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/imooc_homepage_sc?autoReconnect=true&useUnicode=true&characterEncoding=utf8&useSSL=false
    username: root
    password: 123456
    driver-class-name: com.mysql.jdbc.Driver
    tomcat:
      max-active: 4
      min-idle: 2
      initial-size: 2

eureka:
  client:
    service-url:
      defaultZone: http://server1:8000/eureka/

feign:
  hystrix:
    enabled: true

Directory services structure

 

 

Feign defined interfaces

Import com.imooc.homepage.CourseInfo;
 Import com.imooc.homepage.CourseInfosRequest;
 Import org.springframework.cloud.openfeign.FeignClient;
 Import org.springframework.web.bind.annotation.RequestBody;
 Import org.springframework.web.bind .annotation.RequestMapping;
 Import org.springframework.web.bind.annotation.RequestMethod; 

Import java.util.List; 

/ ** 
 * access other services through micro Feign 
 * users access to micro-service courses micro services 
 * / 
@FeignClient (value = "Eureka-Client-Homepage-Course" , 
                fallback = CourseClientHystrix. class )
 public interface CourseClient {

    @RequestMapping(value = "/homepage-course/get/course",
            method = RequestMethod.GET)
    CourseInfo getCourseInfo(Long id);

    @RequestMapping(value = "/homepage-course/get/courses",
            method = RequestMethod.POST)
    List<CourseInfo> getCourseInfos(@RequestBody CourseInfosRequest request);
}

 

 

Written fusing strategy and methods of the class to name Fegin interface definition to be the same, so to achieve its interface

import com.imooc.homepage.CourseInfo;
import com.imooc.homepage.CourseInfosRequest;
import org.springframework.stereotype.Component;

import java.util.Collections;
import java.util.List;

/**
 * 熔断降级策略
 */
@Component
public class CourseClientHystrix implements CourseClient{
    @Override
    public CourseInfo getCourseInfo(Long id) {
        return CourseInfo.invalid();
    }

    @Override
    public List<CourseInfo> getCourseInfos(CourseInfosRequest request) {
        return Collections.emptyList();
    }
}