SpringCloud之Feign示例詳解

Feign簡介

Feign 是一個聲明web服務客戶端，這便得編寫web服務客戶端更容易，使用Feign 創建一個接口並對它進行註解，它具有可插拔的註解支持包括Feign註解與JAX-RS註解，Feign還支持可插拔的編碼器與解碼器，Spring Cloud 增加了對Spring MVC的註解，Spring Web 默認使用了HttpMessageConverters, Spring Cloud 集成Ribbon 和Eureka 提供的負載均衡的HTTP客戶端Feign.

聲明式REST客戶端：Feign

先要啟動eureka_register_service工程（註冊中心）和biz-service-0工程（服務生產者）

創建一個maven工程eureka_feign_client

pom.xml

 <parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>1.4.3.RELEASE</version><relativePath/> <!-- lookup parent from repository --></parent><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><java.version>1.8</java.version></properties><dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-feign</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-eureka</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>Brixton.SR5</version> <type>pom</type> <scope>import</scope></dependency> </dependencies></dependencyManagement>

在應用主類中通過@EnableFeignClients註解開啟Feign功能

啟動文件FeignApplication.java

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

定義服務接口類UserClient.java

使用@FeignClient("biz-service-0")註解來綁定該接口對應biz-service-0服務

@FeignClient("biz-service-0")public interface UserClient { @RequestMapping(method = RequestMethod.GET, value = "/getuser") public User getuserinfo(); @RequestMapping(method = RequestMethod.GET, value = "/getuser") public String getuserinfostr(); @RequestMapping(method = RequestMethod.GET, value = "/info") public String info();}

在web層中調用上面定義的UserController，具體如下

@RestControllerpublic class UserController { @Autowired UserClient userClient; @RequestMapping(value = "/getuserinfo", method = RequestMethod.GET) public User getuserinfo() { return userClient.getuserinfo(); } @RequestMapping(value = "/getuserinfostr", method = RequestMethod.GET) public String getuserinfostr() { return userClient.getuserinfostr(); } @RequestMapping(value = "/info", method = RequestMethod.GET) public String info() { return userClient.info(); }}

application.properties配置變量

spring.application.name=feign-consumerserver.port=8004eureka.client.serviceUrl.defaultZone=http://localhost:8000/eureka/

訪問http://127.0.0.1:8004/getuserinfo

總結：

其實通過Feign封裝了HTTP調用服務方法，使得客戶端像調用本地方法那樣直接調用方法，類似Dubbo中暴露遠程服務的方式，區別在於Dubbo是基於私有二進制協議，而Feign本質上還是個HTTP客戶端

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持武林網。