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  • SpringCloud之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,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

      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/> <!-- 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如下:

    @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("service01")注解来绑定该接口对应service01服务

    @FeignClient("service01")
    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UserClient,具体如下

    @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();
        }
     
     
    }

      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。

     
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  • 原文地址:https://www.cnblogs.com/senlinyang/p/8595489.html
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