Spring Cloud（F版）服务调用Feign

忘是亡心i 2021-10-09 04:46 356阅读 0赞

在上一篇文章中，介绍了[【RestTemplate的常见请求方式】][RestTemplate]，这篇文章我们就来讲讲Feign服务调用的使用方法。

Feign是Netflix开发的声明式、模板化的HTTP客户端，可帮助我们更加便捷、优雅的调用HTTP API。而且Feign通过注解来使用，而且和客户端负载均衡Ribbon以及断路器Hystrix能很好的整合使用，这是RestTemplate无法比拟的优势了。

好了，废话不多说了，直接上代码。

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## Feign的使用 ##

#### 1、环境搭建 ####

使用我们上一篇文章中搭建的项目spring-cloud-example，就不重新搭建项目了。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob3VrdW4xMzE0_size_16_color_FFFFFF_t_70]  
这是我搭建的一个maven多模块的测试项目，如果不知道IDEA如何创建多模块项目的可以看一下[【IntelliJ IDEA创建Maven多模块项目】][IntelliJ IDEA_Maven]这篇文章。

此项目中，commons是公共类模块，存放实体类、工具类等，是一个普通的java项目，consumers是消费者，这里我创建两个模块分别是移动端和pc端这两个消费者，providers是提供者，同样也创建了用户以及订单两个提供者。

eureka-server则是服务注册中心，这个就不过多讲解了可以看之前的几篇文章。

这里提供者和消费者都需要引入commons模块的依赖

#### 2、添加依赖 ####

在消费者consumer-mobile中，添加如下依赖

<?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>
    	<parent>
    		<groupId>org.springframework.boot</groupId>
    		<artifactId>spring-boot-starter-parent</artifactId>
    		<version>2.0.3.RELEASE</version>
    		<relativePath/> 
    	</parent>
    	<groupId>com.clarezhou.example</groupId>
    	<artifactId>consumer-mobile</artifactId>
    	<version>1.0-SNAPSHOT</version>
    	<name>consumer-mobile</name>
    	<description>移动端</description>
    
    	<properties>
    		<java.version>1.8</java.version>
    		<spring-cloud.version>Finchley.SR3</spring-cloud.version>
    	</properties>
    
    	<dependencies>
    		
    		<dependency>
    			<groupId>org.springframework.cloud</groupId>
    			<artifactId>spring-cloud-starter-openfeign</artifactId>
            </dependency>
    		
    		<dependency>
    			<groupId>com.clarezhou.example</groupId>
    			<artifactId>commons</artifactId>
    			<version>1.0-SNAPSHOT</version>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-starter-web</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-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、添加注解 ####

在主入口程序添加@EnableFeignClients注解，在项目启动时，会进行包扫描，扫描所有带有@FeignClient的注解进行处理。

package com.clarezhou.example;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.cloud.openfeign.EnableFeignClients;
    
    /**
     * @author clarezhou
     */
    @SpringBootApplication
    @EnableDiscoveryClient
    @EnableFeignClients
    public class ConsumerMobileApplication {
    
    	public static void main(String[] args) {
    		SpringApplication.run(ConsumerMobileApplication.class, args);
    	}
    
    }

#### 4、属性配置 ####

server:
      port: 8101
    spring:
      application:
        name: consumer-mobile
      security:
        user:
          name: admin
          password: 123456
    eureka:
      client:
        serviceUrl:
          defaultZone: http://${spring.security.user.name}:${spring.security.user.password}@localhost:8081/eureka

#### 5、声明服务 ####

创建HelloService接口，添加@FeignClient注解

package com.clarezhou.example.service;
    
    import main.java.com.clarezhou.example.entity.UserInfoEntity;
    import org.springframework.cloud.openfeign.FeignClient;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    
    /**
     * @author clarezhou
     * @date 2019/7/30 14:15
     **/
    @FeignClient(name="PROVIDER-USER")
    public interface HelloService {
    
        @RequestMapping(value = "/hello/getUserInfo",method = RequestMethod.GET)
        UserInfoEntity getUserInfo();
    }

@FeignClient指定提供者进行绑定服务，name后面是服务名称。

提供者是上一篇文章中写的一个例子。

@RequestMapping("getUserInfo")
        public UserInfoEntity getUserInfo(){
            UserInfoEntity user = new UserInfoEntity();
            user.setUsername("张三");
            user.setPassword("123456");
            user.setEmail("132456789@qq.com");
            user.setMobilePhone("13888888888");
            return user;
        }

#### 6、调用服务 ####

创建controller,在controller中使用@Autowired注解注入FeignClient。

package com.clarezhou.example.controller;
    
    import com.clarezhou.example.service.HelloService;
    import main.java.com.clarezhou.example.entity.UserInfoEntity;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    /**
     * @author clarezhou
     * @date 2019/7/30 14:23
     **/
    @RestController
    @RequestMapping("hello")
    public class MobileHelloController {
    
        @Autowired
        private HelloService helloService;
    
        @RequestMapping("getUserInfo")
        public UserInfoEntity getUserInfo(){
            return helloService.getUserInfo();
        }
    }

#### 7、测试 ####

![在这里插入图片描述][20190730143900899.png]

这样，一个简单的Feign服务调用就完成了。

#### 8、参数传递 ####

服务调用当然离不开参数的传递，接下来看看Feign常用的传参方式

首先，提供者提供以下三个接口

@RequestMapping(value = "sayHello1",method = RequestMethod.GET)
        public String sayHello1(@RequestParam("name") String name){
            return " Hello "+name;
        }
    
        @RequestMapping(value = "sayHello2",method = RequestMethod.POST)
        public String sayHello2(@RequestBody UserInfoEntity user){
            return user.toString();
        }
    
        @RequestMapping(value = "sayHelloByName",method = RequestMethod.GET)
        public String sayHello(String name){
            return " Hello "+name;
        }

再者，在consumer-mobile中添加FeignClient接口

@RequestMapping(value = "/hello/sayHelloByName", method = RequestMethod.GET)
        String sayHelloByName(@RequestParam("name") String name);
    
        @RequestMapping(value = "/hello/sayHello1",method = RequestMethod.GET)
        String sayHello1(@RequestParam("name") String name);
    
        @RequestMapping(value = "/hello/sayHello2",method = RequestMethod.POST)
        String sayHello2(@RequestBody UserInfoEntity user);

最后，添加controller调用

@RequestMapping(value = "/sayHelloByName", method = RequestMethod.GET)
        String sayHelloByName(String name){
            return helloService.sayHelloByName(name);
        }
    
        @RequestMapping(value = "sayHello1",method = RequestMethod.GET)
        String sayHello1(String name){
            return helloService.sayHello1(name);
        }
    
        @RequestMapping(value = "sayHello2",method = RequestMethod.GET)
        String sayHello2(){
            UserInfoEntity user = new UserInfoEntity();
            user.setUsername("赵六");
            user.setPassword("123456");
            user.setMobilePhone("13999999999");
            user.setEmail("11111111@qq.com");
            return helloService.sayHello2(user);
        }

运行结果如下：  
![在这里插入图片描述][20190730153625926.png]  
![在这里插入图片描述][20190730153655319.png]  
![在这里插入图片描述][20190730153716415.png]

feign的简单应用就讲到这里了。

[RestTemplate]: https://blog.csdn.net/zhoukun1314/article/details/97429636
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob3VrdW4xMzE0_size_16_color_FFFFFF_t_70]: /images/20211009/e4b75bc25e1142d7b256ef7b27e9bc91.png
[IntelliJ IDEA_Maven]: https://blog.csdn.net/zhoukun1314/article/details/97492658
[20190730143900899.png]: /images/20211009/0b8ffa1d0b724a71827660e26fbca8d6.png
[20190730153625926.png]: /images/20211009/33b5bb5794834f10899bfcca1f4f1c65.png
[20190730153655319.png]: /images/20211009/3b2bf4810ea44e8a842b25d9c2ce4221.png
[20190730153716415.png]: /images/20211009/2c5ae38dc04e4ba68b044868cddd61d2.png