SpringCloud之Feign樣本詳解，springcloudfeign

SpringCloud之Feign樣本詳解，springcloudfeign

Feign簡介

Feign 是一個聲明web服務用戶端，這便得編寫web服務用戶端更容易，使用Feign 建立一個介面並對它進行註解，它具有可插拔的註解支援包括Feign註解與JAX-RS註解，Feign還支援可插拔的編碼器與解碼器，Spring Cloud 增加了對 Spring MVC的註解，Spring Web 預設使用了HttpMessageConverters, Spring Cloud 整合 Ribbon 和 Eureka 提供的負載平衡的HTTP用戶端 Feign.

聲明式REST用戶端：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）

建立一個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

開機檔案FeignApplication.java

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

定義服務介面類UserClient.java

使用@FeignClient("biz-service-0")註解來綁定該介面對應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組態變數

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，使得用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是基於私人二進位協議，而Feign本質上還是個HTTP用戶端

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