一、什么是feign
声明式的web客户端,使得web服务端的写入更加方便;
具有可插拔的注解特性,默认集成了ribbon,与eureka结合。
采用的是基于接口的注解;
实现feign,只需要创建一个接口并添加注解。
二、使用feign实现负载均衡
此节代码依赖前几节代码,全部代码——>git:https://github.com/aeolusway/aeolusway.git
思路:通过feign去调用service-member服务,而service-member 有两个具体的实现ip:如下图
具体调用的是哪一个,取决于feign的负载均衡策略:轮询。
eureka注册中心代码:springCloud(一)eureka 注册中心
一个服务发现者,一个服务提供者:springCloud(二)服务提供和服务发现
一个同名服务提供:springCloud(三)ribbon实现负载均衡
(1)包结构
(2)FeignOrderApp
package com.aeolusway;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
public class FeignOrderApp {
public static void main(String[] args) {
SpringApplication.run(FeignOrderApp.class, args);
}
}
(3)FeignOrder
package com.aeolusway.controller;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@FeignClient("service-member") //service-member 需要调用的服务名称
public interface FeignOrder {
@RequestMapping("/getUsername") //getUsername 服务请求名称需要与service-member 中的服务请求名称相同
public String getFeign();
}
(4)application.yml
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8888/eureka/
server:
port: 8765
spring:
application:
name: service-feign-order
(5)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">
<modelVersion>4.0.0</modelVersion>
<groupId>com.aeolusway</groupId>
<artifactId>SpringCloud-Feign-Order</artifactId>
<version>1.0-SNAPSHOT</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.5.RELEASE</version>
</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.SR1</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
<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>
</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>
</project>