要使 Feign 与 Hystrix 进行整合，我们需要增加 Feign 和 Hystrix 的依赖，修改 POM.xml 中增加以下依赖项如下：

<?xmlversion="1.0"encoding="UTF-8"?>

<projectxmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0http://maven.apache.org/xsd/maven-4.0.0.xsd">

<modelVersion>4.0.0</modelVersion>

<groupId>org.lixue</groupId>

<artifactId>spring-cloud-hystrix-client</artifactId>

<version>0.0.1-SNAPSHOT</version>

<packaging>jar</packaging>

<name>spring-cloud-hystrix-client</name>

<description>DemoprojectforSpringBoot</description>

<parent>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-parent</artifactId>

<version>1.5.4.RELEASE</version>

<relativePath/><!--lookupparentfromrepository-->

</parent>

<properties>

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>

<java.version>1.8</java.version>

<spring-cloud.version>Dalston.SR5</spring-cloud.version>

</properties>

<dependencies>

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-web</artifactId>

</dependency>

<dependency>

<groupId>org.springframework.cloud</groupId>

<artifactId>spring-cloud-starter-eureka</artifactId>

</dependency>

<dependency>

<groupId>org.springframework.cloud</groupId>

<artifactId>spring-cloud-starter-feign</artifactId>

</dependency>

<dependency>

<groupId>org.springframework.cloud</groupId>

<artifactId>spring-cloud-starter-ribbon</artifactId>

</dependency>

<dependency>

<groupId>org.springframework.cloud</groupId>

<artifactId>spring-cloud-starter-hystrix</artifactId>

</dependency>

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-test</artifactId>

<scope>test</scope>

</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>

还需要在 src/main/resources/application.yml 中，开启 Feign 的配置，如下：

#配置应用名称

spring:

application:

name:spring-cloud-hystrix-client

#服务端口

server:

#启用feign的hystrix支持

feign:

hystrix:

enabled:true

#设置eureka服务注册中心的地址，如果多个以逗号分割

eureka:

client:

service-url:

defaultZone:http://eurekaserver01:9000/eureka/,http://eurekaserver02:9000/eureka/

创建 Feign 客户端接口，增加回退的类实现，在 @FeignClient 注解中，设置 fallback 属性，如下：

package org.lixue;

import org.springframework.cloud.netflix.feign.FeignClient;

import org.springframework.stereotype.Component;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RequestParam;

@FeignClient(name="HELLOWORLD-PROVIDER",fallback=HelloWorldFeignClient.HelloWorldFallback.class)

public interface HelloWorldFeignClient{

@RequestMapping(path="/speaks",method=RequestMethod.GET)

String speak(@RequestParam(name="names")Stringname);

@Component

class HelloWorldFallback implements HelloWorldFeignClient{

@Override

public String speak(String name){

return"speakfallbackisname="+name;

}

}

}

只需要使用 @Autowired 注解标注 HelloWorldFeignClient 实例进行自动注入，然后调用 HelloWorldFeignClient 实例的方法即完成调用，如下：

package org.lixue;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RequestParam;

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

import java.util.List;

import java.util.Map;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.Future;

@RestController

public class InvokerController{

@Autowired

private HelloWorldFeignClient helloWorldFeignClient;

@RequestMapping(method=RequestMethod.GET,path="/speakFeign")

public String speakFeign(@RequestParam("name")String name){

return helloWorldFeignClient.speak(name);

}

}

增加 @EnableCircuitBreaker 和 @EnableFeignClients 注解，启用 Feign 和 Hystrix 功能，如下：

package org.lixue;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.boot.web.servlet.ServletComponentScan;

import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;

import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

import org.springframework.cloud.netflix.feign.EnableFeignClients;

@SpringBootApplication

@EnableDiscoveryClient

@EnableCircuitBreaker

@EnableFeignClients

@ServletComponentScan

public class SpringCloudHystrixClientApplication{

public static void main(String[]args){

SpringApplication.run(SpringCloudHystrixClientApplication.class,args);

}

}

由于我们使用了 Ribbon 因此首先启动 eureka-server 和 service-provider 服务，然后启动该项目，访问 http://localhost:8077/speak?name=abc 可以看到能正常返回信息，如下：

Hello World abc Port=8080

此时，关闭 service-provider 服务，然后在访问地址 http://localhost:8077/speak?name=abc 可以看到，由于服务已经不可用，因此执行了该方法的回退返回，返回如下：

speak fallback is name=abc

Feign 与 Hystrix 整合使用时，会自动帮我们生成 CommandKey，格式为：Feign 客户端接口名称#方法名() ，生成的 GroupKey 为 @FeignClient 注解的 name 属性，例如，上面示例生成的 CommandKey 为 HelloWorldFeignClient#speak() ，Groupkey 为 HELLOWORLD-PROVIDER，如果需要针对该 Feign 客户端设置 Hystrix 的配置属性，在 application.yml 中增加配置如下：

#设置Hystrix的属性

hystrix:

command:

HelloWorldFeignClient#speak():

execution:

isolation:

thread:

如果需要设置默认全局属性，则修改 application.yml 配置如下：

#设置Hystrix的属性

hystrix:

command:

default:

execution:

isolation:

thread: