Spring Cloud探路（三）REST 客戶端Feign

Declarative REST Client: Feign

Feign is a declarative web service client. It makes writing web service clients easier.

如上是Spring Cloud文檔中對於Feign的定義，結合之前的兩篇博文，在這里我們就可以吧Feign簡單的理解為用戶（前端）可以直接接觸到的REST接口提供者。在Feign中，我們可以方便的訪問和使用意已經在Erueka服務器中注冊過的服務了。

1、建立maven工程，配置pom.xml文件

    
    
    
            

     
     
     
             
<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-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-test</artifactId>
     
     
     
             
 <scope>test</scope>
     
     
     
             
 </dependency>
     
     
     
             
 </dependencies>
     
     
     
             

     
     
     
             
 <dependencyManagement>
     
     
     
             
 <dependencies>
     
     
     
             
 <dependency>
     
     
     
             
 <groupId>org.springframework.cloud</groupId>
     
     
     
             
 <artifactId>spring-cloud-dependencies</artifactId>
     
     
     
             
 <version>Camden.SR6</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>
    
    
    
            

2、建立包及啟動類

     
     
     
             

      
      
      
              
@Configuration
      
      
      
              
@ComponentScan
      
      
      
              
@EnableAutoConfiguration
      
      
      
              
@EnableEurekaClient
      
      
      
              
@EnableFeignClients
      
      
      
              
@SpringBootApplication
      
      
      
              
public class FeignApplication {
      
      
      
              

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

3、建立接口類，用來調用之前文章中CLIENT-SERVICE1服務的方法hello()

     
     
     
             

      
      
      
              
@FeignClient("CLIENT-SERVICE1")
      
      
      
              
public interface IHello {
      
      
      
              
 @RequestMapping(value = "/hello",method = RequestMethod.GET)
      
      
      
              
 String getHello();
      
      
      
              
}
     
     
     
             

其中@FeignClient中指定需要調用的微服務的名稱，@RequestMapping中指定訪問微服務響應接口的路徑，如之前微服務的hello方法是通過"/hello"路徑訪問，那么這里需要配置一致

4、新建Controller類，為前端提供REST接口

     
     
     
             

      
      
      
              
@RestController
      
      
      
              
public class HelloController {
      
      
      
              
 @Autowired
      
      
      
              
 private IHello iHello;
      
      
      
              

      
      
      
              
 @RequestMapping(value = "gethello",method = RequestMethod.GET)
      
      
      
              
 public String getHello(){
      
      
      
              
 return iHello.getHello();
      
      
      
              
 }
      
      
      
              
}
     
     
     
             

5、配置Feign的配置文件，指定Erureka服務器注冊地址和訪問端口application.yml

     
     
     
             

      
      
      
              
server:
      
      
      
              
 port: 8081
      
      
      
              

      
      
      
              
eureka:
      
      
      
              
 client:
      
      
      
              
 serviceUrl:
      
      
      
              
 defaultZone: http://localhost:1000/eureka/
     
     
     
             

 成功！

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