SpringCloud之Feign(五)

Feign简介

Feign 是一个声明web服务客户端，这便得编写web服务客户端更容易，使用Feign 创建一个接口并对它进行注解，它具有可插拔的注解支持包括Feign注解与JAX-RS注解，Feign还支持可插拔的编码器与解码器，Spring Cloud 增加了对 Spring MVC的注解，Spring Web 默认使用了HttpMessageConverters, Spring Cloud 集成 Ribbon 和 Eureka 提供的负载均衡的HTTP客户端 Feign.

声明式REST客户端：Feign

先要启动eureka_register_service工程（注册中心）和biz-service-0工程（服务生产者）

创建一个maven工程eureka_feign_client

pom.xml

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<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>

在应用主类中通过@EnableFeignClients注解开启Feign功能

启动文件FeignApplication.java

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

定义服务接口类UserClient.java

使用@FeignClient("biz-service-0")注解来绑定该接口对应biz-service-0服务

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@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层中调用上面定义的UserController，具体如下

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@RestController public 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配置变量

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