四、SpringCloud的学习之feign服务间的调用讲解

一、背景

1.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。

2.简而言之

2.1.Feign 采用的是基于接口的注解

2.2.Feign 整合了ribbon

3.我自己理解的就是服务与服务之间的调用用到的是feign，下面我就通过一个具体的小案例来讲解这个feign.

二、项目结构

三、项目中的各个配置

1.pom.xml

<?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>1.5.2.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.example</groupId>
	<artifactId>demo-serviceorder-fegin</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>demo-serviceorder-fegin</name>
	<description>Demo project for Spring Boot</description>

	<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>

2.controller

@RestController
public class FeignMemberController {
	@Autowired
	private MemberFeign memberFeign;

	@RequestMapping("/getFeignOrderByUserList")
	public List<String> getFeignOrderByUserList() {
		return memberFeign.getOrderByUserList();
	}
}

3.service

@FeignClient("demo-service-member")
public interface MemberFeign {
	@RequestMapping("/getMemberAll")
	public List<String> getOrderByUserList();
}

4.application.yml

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

4.启动类

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
public class DemoServiceorderFeginApplication {

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

}

5.分别依次启动项目Eurka、项目demo-service-member、项目demo-serviceorder-feign、具体哪个项目可以参看我前一个博客：https://blog.csdn.net/chenmingxu438521/article/details/90514885

四、效果图

1.Eureka注册中心

2.服务间调用的结果数据

五、总结

希望能帮到你们，下几篇讲解，熔断，晚安，各位！！！

四、SpringCloud的学习之feign服务间的调用讲解

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