SpringCloud之Feign

本文内容纲要：

-声明式REST客户端：Feign

Fegin是一个声明似的web服务客户端，它使得编写web服务客户端变得更加容易。使用Fegin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，SpringCloud增加了对SpringMVC的注解，SpringWeb默认使用了HttpMessageConverters,SpringCloud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

创建一个maven工程eureka_feign_client，pom文件如下：

<parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.4.3.RELEASE</version> <relativePath/><!--lookupparentfromrepository--> </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如下：

@SpringBootApplication @EnableDiscoveryClient @EnableFeignClients publicclassFeignApplication{ publicstaticvoidmain(String[]args){ SpringApplication.run(FeignApplication.class,args); } }

定义服务接口类UserClient.java，使用@FeignClient("service01")注解来绑定该接口对应service01服务

@FeignClient("service01") publicinterfaceUserClient{ @RequestMapping(method=RequestMethod.GET,value="/getuser") publicUsergetuserinfo(); @RequestMapping(method=RequestMethod.GET,value="/getuser") publicStringgetuserinfostr(); @RequestMapping(method=RequestMethod.GET,value="/info") publicStringinfo(); }

在web层中调用上面定义的UserClient，具体如下

@RestController publicclassUserController{ @Autowired UserClientuserClient; @RequestMapping(value="/getuserinfo",method=RequestMethod.GET) publicUsergetuserinfo(){ returnuserClient.getuserinfo(); } @RequestMapping(value="/getuserinfostr",method=RequestMethod.GET) publicStringgetuserinfostr(){ returnuserClient.getuserinfostr(); } @RequestMapping(value="/info",method=RequestMethod.GET) publicStringinfo(){ returnuserClient.info(); } }

其实通过Feign封装了HTTP调用服务方法，使得客户端像调用本地方法那样直接调用方法，类似Dubbo中暴露远程服务的方式，区别在于Dubbo是基于私有二进制协议，而Feign本质上还是个HTTP客户端。

本文内容总结：声明式REST客户端：Feign，

原文链接：https://www.cnblogs.com/senlinyang/p/8595489.html