SpringCloud-创建服务消费者-Feign方式(附代码下载)

Myth丶恋晨 2023-10-11 13:48 46阅读 0赞

## 场景 ##

SpringCloud-服务注册与实现-Eureka创建服务注册中心(附源码下载)：

[https://blog.csdn.net/BADAO\_LIUMANG\_QIZHI/article/details/102535957][https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_102535957]

SpringCloud-服务注册与实现-Eureka创建服务提供者(附源码下载)：

[https://blog.csdn.net/BADAO\_LIUMANG\_QIZHI/article/details/102558004][https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_102558004]

SpringCloud-创建服务消费者-Ribbon方式(附代码下载)：

[https://blog.csdn.net/BADAO\_LIUMANG\_QIZHI/article/details/102558080][https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_102558080]

在上面已经实现服务注册中心、服务提供者和以Ribbon方式实现服务消费者的前提下，使用另一种Feign方式实现服务消费者。

### Feign ###

Feign 是一个声明式的伪 Http 客户端，它使得写 Http 客户端变得更简单。使用 Feign，只需要创建一个接口并注解。它具有可插拔的注解特性，可使用 Feign 注解和 JAX-RS 注解。Feign 支持可插拔的编码器和解码器。Feign 默认集成了 Ribbon，并和 Eureka 结合，默认实现了负载均衡的效果

注：

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[https://blog.csdn.net/badao\_liumang\_qizhi][https_blog.csdn.net_badao_liumang_qizhi]  
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## 实现 ##

参考上面构建项目的方式，依次建立目录hello-spring-cloud-web-admin-feign目录以及在

目录下新建pom.xml，并将其托管。然后新建src/main/java目录和src/main/resources目录并分别进行目录设置。

然后在java下新建包，包下新建启动类，在resources下新建配置文件application.yml。

完成后的目录为：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70][]

pom.xml代码：

<?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>
    
        <parent>
            <groupId>com.badao</groupId>
            <artifactId>hello-spring-cloud-dependencies</artifactId>
            <version>1.0.0-SNAPSHOT</version>
            <relativePath>../hello-spring-cloud-dependencies/pom.xml</relativePath>
        </parent>
    
        <artifactId>hello-spring-cloud-web-admin-feign</artifactId>
        <packaging>jar</packaging>
    
        <name>hello-spring-cloud-web-admin-feign</name>
        <url>https://blog.csdn.net/badao_liumang_qizhi</url>
        <inceptionYear>2019-Now</inceptionYear>
    
        <dependencies>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-tomcat</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-thymeleaf</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
            
    
            
            <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-openfeign</artifactId>
            </dependency>
            
    
            
            <dependency>
                <groupId>net.sourceforge.nekohtml</groupId>
                <artifactId>nekohtml</artifactId>
            </dependency>
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                    <configuration>
                        <mainClass>com.badao.hello.spring.cloud.web.admin.feign.WebAdminFeignApplication</mainClass>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    </project>

注：

这里的parent标签要与上面的统一的依赖管理对应起来。

要修改指定的程序入口类为自己相应的路径。

然后应用启动类的代码：

package com.badao.hello.spring.cloud.web.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 WebAdminFeignApplication {
        public static void main(String[] args) {
            SpringApplication.run(WebAdminFeignApplication.class, args);
        }
    }

注：

通过 @EnableDiscoveryClient 注解注册到服务中心

通过 @EnableFeignClients 注解开启 Feign 功能

然后是配置文件application.yml

spring:
      application:
        name: hello-spring-cloud-web-admin-feign
      thymeleaf:
        cache: false
        mode: LEGACYHTML5
        encoding: UTF-8
        servlet:
          content-type: text/html
    
    server:
      port: 8765
    
    eureka:
      client:
        serviceUrl:
          defaultZone: http://localhost:8761/eureka/

注：

1.服务注册与发现是根据上面的name去寻找。

2.port表示端口号。

3.serviceURL设置eureka的地址，与上面创建服务注册中心时的URL对应。

与使用Ribbon方式不同的是，这里需要创建service接口，而不是service类。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 1][]

AdminService接口代码：

package com.badao.hello.spring.cloud.web.feign.service;
    
    import org.springframework.cloud.openfeign.FeignClient;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RequestParam;
    
    @FeignClient(value = "hello-spring-cloud-service-admin")
    public interface AdminService {
    
        @RequestMapping(value = "hi", method = RequestMethod.GET)
        public String sayHi(@RequestParam(value = "message") String message);
    }

注：

通过@FeignClient(value = "hello-spring-cloud-service-admin")来指定调用哪个服务。

这里就是对应上面服务提供者的配置文件的name属性。

然后再新建Controller包，包下新建AdminController

package com.badao.hello.spring.cloud.web.feign.controller;
    
    
    import com.badao.hello.spring.cloud.web.feign.service.AdminService;
    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;
    
    @RestController
    public class AdminController {
    
        @Autowired
        private AdminService adminService;
    
        @RequestMapping(value = "hi", method = RequestMethod.GET)
        public String sayHi(@RequestParam String message) {
            return adminService.sayHi(message);
        }
    }

为了体现出负载均衡效果，我们要启动两台service-admin，即启动两个服务提供者。

我们先启动服务注册中心Eureka服务8761端口，再以8762端口启动一个服务提供者，然后点击Run-Edit Configuration，将启动单实例去掉。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 2][]

然后修改服务提供者的配置文件中端口号为8763，再启动一个服务提供者。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 3][]

消费者要想实现负载均衡的效果，应该一会访问8762的服务提供者，一会访问8763的服务提供者。

然后运行当前服务消费者的启动程序。

打开浏览器输入：

[http://localhost:8765/hi?message=HelloFeign][http_localhost_8765_hi_message_HelloFeign]

![20191016220728572.gif][]

此时的架构

一个服务注册中心，Eureka Server，端口号为：8761  
service-admin 工程运行了两个实例，端口号分别为：8762，8763  
web-admin-feign 工程端口号为：8765

### 源码下载 ###

[https://download.csdn.net/download/badao\_liumang\_qizhi/11867357][https_download.csdn.net_download_badao_liumang_qizhi_11867357]

###     ###

[https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_102535957]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/102535957
[https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_102558004]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/102558004
[https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_102558080]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/102558080
[https_blog.csdn.net_badao_liumang_qizhi]: https://blog.csdn.net/badao_liumang_qizhi
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20191016220411241.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20191016220555838.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20191016220650877.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 3]: https://img-blog.csdnimg.cn/20191016220700760.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[http_localhost_8765_hi_message_HelloFeign]: http://localhost:8765/hi?message=HelloFeign
[20191016220728572.gif]: https://img-blog.csdnimg.cn/20191016220728572.gif
[https_download.csdn.net_download_badao_liumang_qizhi_11867357]: https://download.csdn.net/download/badao_liumang_qizhi/11867357