springcloud 系列入门教程整理（之三） feign 消费者

àì夳堔傛蜴生んèń 2022-02-19 16:59 202阅读 0赞

之一传送门：[注册中心eureka][eureka]

之二传送门：[feign服务提供者][feign]

（1）搭建一个普通的maven项目

（2）pom 如下添加依赖

<?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>
    
        <groupId>com.zhihao</groupId>
        <artifactId>feignConsumer</artifactId>
        <version>1.0-SNAPSHOT</version>
    
        <name>feigncomsumer</name>
    
        <properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            <maven.compiler.source>1.8</maven.compiler.source>
            <maven.compiler.target>1.8</maven.compiler.target>
        </properties>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.0.0.RELEASE</version>
        </parent>
    
        <dependencyManagement>
            <dependencies>
                <dependency>
                    <groupId>org.springframework.cloud</groupId>
                    <artifactId>spring-cloud-dependencies</artifactId>
                    <version>Finchley.BUILD-SNAPSHOT</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
            </dependencies>
        </dependencyManagement>
    
        <dependencies>
    
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-openfeign</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.11</version>
                <scope>test</scope>
            </dependency>
    
        </dependencies>
    
        <repositories>
            <repository>
                <id>spring-snapshots</id>
                <name>Spring Snapshots</name>
                <url>https://repo.spring.io/libs-snapshot</url>
                <snapshots>
                    <enabled>true</enabled>
                </snapshots>
            </repository>
        </repositories>
    
        <build>
            <finalName>feigncomsumer</finalName>
        </build>
    
    
    </project>

（2）实体类，不是必要的，只是为了返回对象而创建

package com.zhihao.model;
    
    public class Result {
    
        private int code;
    
        private String message;
    
        private Object content;
    
        private String serviceName;
    
        private String host;
    
    //已省略get和set方法
    }

（3）创建一个service，来调用那个提供服务的系统。

@FeignClient(value = "feignService") value对应那个系统的实例名。

@RequestMapping(value = "/who")  这个"/who" 对应提供服务的系统的接口路径，匹配的话，会调用提供服务系统的接口。

import com.zhihao.model.Plus;
    import com.zhihao.model.Result;
    import org.springframework.cloud.openfeign.FeignClient;
    import org.springframework.web.bind.annotation.RequestBody;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RequestParam;
    
    @FeignClient(value = "feignService")
    public interface TestService {
    
        @RequestMapping(value = "/who")
        Result who();
    }

（3）创建本系统的接口类controller

package com.zhihao.controller;
    
    import com.zhihao.service.TestService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestBody;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    public class TestFeignController {
    
        @Autowired
        private TestService testService;
    
        @RequestMapping("/isWho")
        public Object isWho(Plus plus){
            return testService.who();
        }
    
    
    }

（4）启动类

import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.cloud.openfeign.EnableFeignClients;
    
    @EnableFeignClients
    @EnableDiscoveryClient
    @SpringBootApplication
    public class FeignConsumerApp {
    
        public static void main(String[] args) {
            SpringApplication.run(FeignConsumerApp.class, args);
        }
    
    }

（5）配置文件application.yml

server:
      port: 8700
    
    spring:
      application:
        name: feignComsumer
    
    eureka:
      client:
        serviceUrl:
          defaultZone: http://localhost:8800/eureka/

（6）启动本系统，会看到注册到注册中心（先启动注册中心和服务提供系统）。

如下网址访问本系统（feign消费者），会看到feign服务提供系统（feign服务提供者）返回的对象。

![2019041621524191.png][]

（7）有一个注意点，如果报错说TestService 找不到，需要在启动类的注解加上TestService 的所在包，让它扫描到feign的service。

@EnableFeignClients({ "com.zhihao.feign" })

[eureka]: https://blog.csdn.net/neymar_jr/article/details/89342457
[feign]: https://blog.csdn.net/neymar_jr/article/details/89342705
[2019041621524191.png]: /images/20220219/18d2735f17bf4ae38142adc91411aee3.png