spring-clound 学习打卡3：简单入门-服务消费，基于【Feign】【Greenwich.SR1版本】

偏执的太偏执、 2022-04-24 10:18 69阅读 0赞

# spring-clound 学习打卡3：简单入门-服务消费，基于【Feign】 【Greenwich.SR1版本】 #

# 一、简介 #

> 工程传送门  
> [https://github.com/unnunique/SpringCloundDakaLearning/tree/master/Chapter-3][https_github.com_unnunique_SpringCloundDakaLearning_tree_master_Chapter-3]

利用feign 可以访问注册在服务中心的服务，自带负载均衡功能。  
Feign默认集成了Ribbon，并和Eureka结合，默认实现了负载均衡的效果。

> 简而言之：  
> Feign 采用的是基于接口的注解  
> Feign 整合了ribbon，具有负载均衡的能力  
> 整合了Hystrix，具有熔断的能力

# 二、准备工作 #

继续用第一篇的工程， 启动server，端口为8761; 启动client 两次，端口分别为8762 、8773.

# 三、上代码。 #

## 3.1 pom 文件 ##

<?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">
        <parent>
            <artifactId>parent</artifactId>
            <groupId>com.sydney.dream.springclound</groupId>
            <version>1.0.0</version>
        </parent>
        <modelVersion>4.0.0</modelVersion>
    
        <artifactId>chapter-3</artifactId>
    
    
        <properties>
            <java.version>1.8</java.version>
            <spring-cloud.version>Greenwich.SR1</spring-cloud.version>
        </properties>
    
        <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.cloud</groupId>
                <artifactId>spring-cloud-starter-openfeign</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>

## 3.2 properties ##

server.port=8765
    
    spring.application.name=service-consumer-client-demo2
    
    eureka.instance.hostname=localhost
    eureka.client.register-with-eureka=true
    eureka.client.fetch-registry=true
    eureka.client.service-url.default-zone=http://${eureka.instance.hostname}:${server.port}/eureka/
    
    remote.eureka.servername=srvice-clientdemo

## 3.3 application ##

注意添加@EnableFeignClients

package com.sydney.dream;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
    import org.springframework.cloud.openfeign.EnableFeignClients;
    import org.springframework.context.annotation.ComponentScan;
    
    @SpringBootApplication
    @EnableEurekaClient
    @EnableDiscoveryClient
    @EnableFeignClients
    public class FeignClientDemoApp { 
        public static void main(String[] args) { 
            SpringApplication.run(FeignClientDemoApp.class, args);
        }
    }

## 3.4 编写消费服务 ##

package com.sydney.dream.chapter3;
    
    import org.springframework.cloud.openfeign.FeignClient;
    import org.springframework.stereotype.Component;
    import org.springframework.web.bind.annotation.PostMapping;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    
    @FeignClient(value = "${remote.eureka.servername}")
    @Component
    public interface HelloWorldService { 
        @PostMapping(value = "/hi")
        String getHello(@RequestParam("name") String name);
    }

## 3.5 controller ##

package com.sydney.dream.chapter3;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    public class HelloWorldController { 
    
        @Autowired
        private HelloWorldService helloWorldService;
    
        @RequestMapping("/hi")
        public String getHelloWorld(String name) { 
            return helloWorldService.getHello(name);
        }
    }

# 四、启动服务 #

启动程序，多次访问http://localhost:8765/hi?name=forezp,浏览器交替显示：

> hi didi,i am from port:8762  
> hi didi,i am from port:8763

[https_github.com_unnunique_SpringCloundDakaLearning_tree_master_Chapter-3]: https://github.com/unnunique/SpringCloundDakaLearning/tree/master/Chapter-3