企業分佈式微服務雲SpringCloud SpringBoot mybatis （三） 服務消費者（Feign）

1、Feign簡介

Feign是一個聲明式的僞Http客戶端，它使得寫Http客戶端變得更簡單。使用Feign，只須要建立一個接口並註解。它具備可插拔的註解特性，可以使用Feign 註解和JAX-RS註解。Feign支持可插拔的編碼器和解碼器。Feign默認集成了Ribbon，並和Eureka結合，默認實現了負載均衡的效果。

簡而言之：

• Feign 採用的是基於接口的註解
• Feign 整合了ribbon

2、準備工做

繼續用上一節的工程， 啓動eureka-server，端口爲8761; 啓動service-hi 兩次，端口分別爲8762 、8773.

3、建立一個feign的服務

新建一個spring-boot工程，取名爲serice-feign，在它的pom文件引入Feign的起步依賴spring-cloud-starter-feign、Eureka的起步依賴spring-cloud-starter-eureka、Web的起步依賴spring-boot-starter-web，代碼以下：

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<?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.forezp</groupId> <artifactId>service-feign</artifactId> <version> 0.0 . 1 -SNAPSHOT</version> <packaging>jar</packaging> <name>service-feign</name> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version> 1.5 . 2 .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> </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-feign</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</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>

　　

在工程的配置文件application.yml文件，指定程序名爲service-feign，端口號爲8765，服務註冊地址爲http://localhost:8761/eureka/ ，代碼以下：
複製代碼

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eureka: client: serviceUrl: defaultZone: http: //localhost:8761/eureka/ server: port: 8765 spring: application: name: service-feign

　　在程序的啓動類ServiceFeignApplication ，加上@EnableFeignClients註解開啓Feign的功能：

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@SpringBootApplication @EnableDiscoveryClient @EnableFeignClients public class ServiceFeignApplication { public static void main(String[] args) { SpringApplication.run(ServiceFeignApplication. class , args); } }

　　定義一個feign接口，經過@ FeignClient（「服務名」），來指定調用哪一個服務。好比在代碼中調用了service-hi服務的「/hi」接口，代碼以下：

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/** * Created by fangzhipeng on 2017/4/6. */ @FeignClient (value = "service-hi" ) public interface SchedualServiceHi { @RequestMapping (value = "/hi" ,method = RequestMethod.GET) String sayHiFromClientOne( @RequestParam (value = "name" ) String name); }

　　在Web層的controller層，對外暴露一個」/hi」的API接口，經過上面定義的Feign客戶端SchedualServiceHi 來消費服務。代碼以下：

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@RestController public class HiController { @Autowired SchedualServiceHi schedualServiceHi; @RequestMapping (value = "/hi" ,method = RequestMethod.GET) public String sayHi( @RequestParam String name){ return schedualServiceHi.sayHiFromClientOne(name); } }

　　架構代碼以下:

資料和源碼來源地址

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