一. 简介

二. 搭建Feign

2.1 pom.xml

注：需要引入eureka, feign, openfeign, web依赖

<?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">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>feign</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>feign</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.2.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </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>Finchley.RELEASE</spring-cloud.version>
    </properties>

    <dependencies>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-feign</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-web</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>

2.2 application.yml

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8760/eureka/

server:
  port: 8762

spring:
  application:
    name: feign

feign:
  hystrix:
    enabled: true

2.3 启动类

package com.example.feign;

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
public class FeignApplication {

    public static void main(String[] args) {
        SpringApplication.run(FeignApplication.class, args);
        System.out.println("feign has started!");
    }

}

注: @EnableFeignClients注解表明是一个Feign工程。

2.4 Controller类

package com.example.feign;

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;

@RestController
public class SayHelloController {

    @Autowired
    private SayHelloService sayHelloService;

    @GetMapping(value = "/sayHello")
    public String sayHello(@RequestParam String name) {
        return this.sayHelloService.sayHello(name);
    }

}

2.5 对外暴露接口

package com.example.feign;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.stereotype.Service;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;

/**
 * eurekaclient为提供服务的名称
 */
@FeignClient(value = "eurekaclient", fallback = SayHelloServiceHystrix.class)
@Service
public interface SayHelloService {

    @GetMapping(value = "/sayHello")
    String sayHello(@RequestParam(value = "name") String name);

}

注： eurekaclient为提供服务的名称，也就是之前配置的俩个eureka客户端名称。

feign默认集成了ribbon, 也会自动解析。

2.6 启动查看

注：如上图，说明启动成功。

三. 负载测试

3.1 测试

输入路径： http://localhost:8762/sayHello?name=dxb 进行访问，刷新页面会交替出现如下内容：

8766 eurekaclient is accessing....dxb

8767 eurekaclient is accessing....dxb

注： ribbon默认采用的轮询的负载均衡策略。

3.2 原理

四. 代码路径

github路径：https://github.com/1956025812/springcloud

代码已提交，欢迎大家参考

springcloud系列(三)----Feign