springCloud Finchley 微服务架构从入门到精通【四】服务消费者(feign)

程序员文章站 2024-03-17 22:53:10

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上篇文章我们写了service-user服务提供者，并使用ribbon的方式去调用，本次，我们依然使用上一章节中的service-user作为服务提供者，改为使用feign去消费这个微服务

feign客户端和ribbon 类似，同样实现了客户端的负载均衡，与ribbon不同的是，feign的调用与本地接口的调用更加类似，并且更加便捷、更加优雅，传入参数较多时得以体现，当然，在实际项目中，两者可能都会用到，下面来写一下feign的实现

一、创建一个服务消费者 feign

1、创建项目

springCloud Finchley 微服务架构从入门到精通【四】服务消费者(feign)

选择Feign 和 Eureka Server点击完成

springCloud Finchley 微服务架构从入门到精通【四】服务消费者(feign)

pom.xml如下：

<?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.mayi.springcloud</groupId>
    <artifactId>bussnessservice-user-client-feign</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>bussnessservice-user-client-feign</name>
    <description>用户中心服务调用者feign</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Finchley.M9</spring-cloud.version>
    </properties>

    <dependencies>
        <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>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>

    <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>

2、修改配置

bootstrap.yml

spring:
  application:
    name: service-user-client-feign
server:
  port: 9001

在启动类添加@EnableFeignClients以启动feign客户端

package com.mayi.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
public class BussnessserviceUserClientFeignApplication {

    public static void main(String[] args) {
        SpringApplication.run(BussnessserviceUserClientFeignApplication.class, args);
    }
}

3、具体实现代码

新建两个包：api 和 client 并创建相应的实现类

springCloud Finchley 微服务架构从入门到精通【四】服务消费者(feign)

说明： UserFeignClien**t 是**feign接口， UserFeignApi 是feign接口的调用者

UserFeignClient 代码如下：

package com.mayi.springcloud.client;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

@FeignClient(name="service-user")
public interface UserFeignClient {

    @GetMapping("/listUsers")
    public String listUsers();

}

解释：

@FeignClient(name=”service-user”) 标明feign调用的微服务名称
@GetMapping(“/listUsers”) 对应service-user微服务中的URL

UserFeignApi 代码如下：

package com.mayi.springcloud.api;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import com.mayi.springcloud.client.UserFeignClient;

@RestController
public class UserFeignApi {

    @Autowired
    private UserFeignClient userFeignClient;


    @GetMapping("/listUsersByFeign")
    public String ListUsers(){
        String users = this.userFeignClient.listUsers();
        return users;
    }

}