Spring Cloud Feign 服务消费者

今天药忘吃喽~ 2022-03-25 09:36 237阅读 0赞

## 服务消费者（Feign） ##

### 什么是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。

简而言之：

*  Feign 采用的是基于接口的注解
 *  Feign 整合了ribbon

### 创建service-order-feign工程 ###

Maven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.cc.feign.order</groupId>
        <artifactId>service-order-feign</artifactId>
        <version>1.0-SNAPSHOT</version>
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>1.5.2.RELEASE</version>
            <relativePath /> 
        </parent>
    
        <properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
            <java.version>1.8</java.version>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-eureka</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-ribbon</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-feign</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>Dalston.RC1</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>
    
        <repositories>
            <repository>
                <id>spring-milestones</id>
                <name>Spring Milestones</name>
                <url>https://repo.spring.io/milestone</url>
                <snapshots>
                    <enabled>false</enabled>
                </snapshots>
            </repository>
        </repositories>
    
    
    </project>

application.yml配置

eureka:
      client:
        serviceUrl:
          defaultZone: http://localhost:8888/eureka/
    server:
      port: 8765
    spring:
      application:
        name: service-order-feign

编写service,调用service-member

package com.cc.feign.order;
    
    import org.springframework.cloud.netflix.feign.FeignClient;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    import java.util.List;
    
    @FeignClient("service-member")
    public interface MemberFeign {
    	@RequestMapping("/getUserList")
    	public List<String> getOrderByUserList();
    }

@FeignClient 需要调用服务名称，@RequestMapping服务请求名称

对应会员服务（service-member）：

package com.cc.member;
    
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import java.util.ArrayList;
    import java.util.List;
    
    @RestController
    public class MemberController {
    
        @Value("${server.port}")
        private String port;
    
        @RequestMapping("/getUserList")
        public List<String> getUserList() {
            List<String> listUser = new ArrayList<String>();
            listUser.add("zhangsan");
            listUser.add("lisi");
            listUser.add("yushengjun");
            listUser.add(port);
            return listUser;
        }
    
    }

order服务controller：

package com.cc.feign.order;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import java.util.List;
    
    @RestController
    public class MemberFeignController {
    
        @Autowired
        private MemberFeign memberFeign;
    
        @RequestMapping("/getUserList")
        public List<String> getUserList(){
            return memberFeign.getOrderByUserList();
        }
    }

启动类

package com.cc.feign.order;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
    import org.springframework.cloud.netflix.feign.EnableFeignClients;
    
    @SpringBootApplication
    @EnableEurekaClient
    @EnableFeignClients
    public class OrderFeignApp {
    
    	public static void main(String[] args) {
    		SpringApplication.run(OrderFeignApp.class, args);
    	}
    
    }

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