springcloud之feign小栗子

淡淡的烟草味﹌ 2022-12-17 11:59 147阅读 0赞

## 写在前面 ##

源码在[这里][Link 1]。本例在[这篇博客][Link 2]基础上进行讲解。再贴下图，回顾下当前的架构：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dhbmcwOTA3_size_16_color_FFFFFF_t_70_pic_center]  
当前有一个端口号为`8671`的eureka的服务端实例，端口号为`8672`,`8673`的eureka客户端相同应用的两个实例，端口号为`8674`的ribbon的eureka的客户端实例。这里我们再添加一个模块`my-service-feign`基于feign的方式来调用`myeureka-client`的服务。

## 1：创建`my-service-feign` ##

### 1.1：创建项目 ###

`new`\->`module`,选择`Spring Inilializr`以及java8，然后next，录入gav等信息，创建完成后如下图：  
![在这里插入图片描述][20201023165628729.jpg_pic_center]

### 1.2：设置parent ###

<parent>
      <groupId>dongshi.daddy</groupId>
      <artifactId>my-eureka</artifactId>
      <version>1.0-SNAPSHOT</version>
      <relativePath/> 
    </parent>

### 1.3：引入依赖 ###

<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>
    </dependencies>

### 1.4：完整pom ###

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
      <modelVersion>4.0.0</modelVersion>
    
      <groupId>dongshi.daddy</groupId>
      <artifactId>my-service-feign</artifactId>
      <version>0.0.1-SNAPSHOT</version>
      <packaging>jar</packaging>
    
      <name>my-service-feign</name>
      <description>Demo project for Spring Boot</description>
    
      <parent>
        <groupId>dongshi.daddy</groupId>
        <artifactId>my-eureka</artifactId>
        <version>1.0-SNAPSHOT</version>
        <relativePath/> 
      </parent>
    
      <properties>
        <java.version>1.8</java.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>
      </dependencies>
    
      <build>
        <plugins>
          <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
          </plugin>
        </plugins>
      </build>
    
    </project>

### 1.5：配置文件 ###

server:
      port: 8765
    
    eureka:
      client:
        serviceUrl:
          defaultZone: http://localhost:8761/eureka/
    
    spring:
      application:
        name: dongshidaddy-first-feign-client

### 1.6：启用相关注解 ###

@SpringBootApplication
    @EnableEurekaClient
    @EnableDiscoveryClient
    @EnableFeignClients

这里的`@EnableFeignClients`是启用feign客户端。  
完整代码如下：

@SpringBootApplication
    @EnableEurekaClient
    @EnableDiscoveryClient
    @EnableFeignClients
    public class MyServiceFeignApplication { 
    
        public static void main(String[] args) { 
            SpringApplication.run(MyServiceFeignApplication.class, args);
        }
    
    }

### 1.7：配置基于feign的service ###

@FeignClient(value = "DONGSHIDADDY-FIRST-EUREKA-CLIENT")
    public interface SchedualServiceHi { 
    
        @RequestMapping(value = "/hi",method = RequestMethod.GET)
        String sayHiFromClientOne(@RequestParam(value = "name") String name);
    
    }

其中`@FeignClient(value = "DONGSHIDADDY-FIRST-EUREKA-CLIENT")`是指定调用服务名为`DONGSHIDADDY-FIRST-EUREKA-CLIENT`提供的服务，这里注意改成自己的。方法`sayHiFromClientOne`通过rest风格接口的方式配置了调用了接口的[Mapping][]信息。

### 1.8：配置controller ###

@RestController
    public class HiController { 
    
        @Autowired
        SchedualServiceHi schedualServiceHi;
    
        @GetMapping(value = "/hi")
        public String sayHi(@RequestParam String name) { 
            return schedualServiceHi.sayHiFromClientOne( name );
        }
    }

## 2：测试 ##

### 2.1：启动`my-enreka-server` ###

该服务是eureka的服务端，作为服务的注册中心使用，端口号是`8761`。

### 2.2：启动`myeureka-client`第1个实例 ###

修改配置文件设置端口号为`8762`，然后启动。

### 2.3：启动`myeureka-client`第2个实例 ###

修改端口号为`8763`。注意不能直接启动，需要在`Edit Configurations`下添加一个springboot的程序，然后设置名称和主函数，如下图：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dhbmcwOTA3_size_16_color_FFFFFF_t_70_pic_center 1]  
启动成功后，查看`http://localhost:8761/`可以看到`myeureka-client`的实例注册了两个，端口号分别为`8762`,`8763`。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dhbmcwOTA3_size_16_color_FFFFFF_t_70_pic_center 2]

### 2.4：启动`my-service-feign` ###

启动后可以在eureka服务端看到注册的信息，如下图：  
![在这里插入图片描述][20201023170607715.jpg_pic_center]

### 2.5：访问接口 ###

如下重复访问，可以在`myeureka-client`的两个实例中进行负载调用：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dhbmcwOTA3_size_16_color_FFFFFF_t_70_pic_center 3]

## 3：项目架构 ##

此时系统中有`1`个eureka的服务端，端口号为`8761`,`3`个eureka客户端，分别是`myeureka-client`,`my-service-ribbon`，`my-service-feign`，其中myeureka-client启动`2个实例`，端口号分别是`8762`和`8763`，my-service-ribbon和my-service-feign调用myeureka-client提供的服务。最终结构如下图：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dhbmcwOTA3_size_16_color_FFFFFF_t_70_pic_center 4]  
其中的`蓝色边框`框起来的就是本文添加的部分。

## 最后：都让开，我要喝瑞幸 ##

![在这里插入图片描述][20200828090303329.png_pic_center]

[Link 1]: https://download.csdn.net/download/wang0907/13032875
[Link 2]: https://blog.csdn.net/wang0907/article/details/109241299
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[20201023165628729.jpg_pic_center]: /images/20221122/9282ced8593f426f89d742494fa581df.png
[Mapping]: https://blog.csdn.net/wang0907/article/details/108960496
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