SpringCloud组件之Feign

朱雀 2023-03-01 13:52 216阅读 0赞

## SpringCloud五大组件之Feign ##

**一、Feign简介（GitHub上的描述）**

> Feign is a Java to Http client binder inspired by Retrofit, JAXRS-2.0, and WebSocket. Feign’s first goal was reducing the complexity of binding Denominator uniformly to Http APIs regardless of ReSTfulness.  
> 翻译：Feign是受Retrofit，JAXRS-2.0和WebSocket启发的Java到Http客户端绑定程序。 Feign的第一个目标是减少与ReSTfulness无关的将Denominator统一绑定到Http API的复杂性。  
> Feign是一个声明式的伪HTTP客户端，它使得写HTTP客户端变得更简单。使用Feign，只需要创建一个接口并注解。

**二、我们使用上节讲到的User服务，进行服务改造。Pom配置如下：**

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <parent>
            <groupId>父GroupId</groupId>
            <artifactId>父ArtifactId</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </parent>
        <modelVersion>4.0.0</modelVersion>
    
        <artifactId>member</artifactId>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-openfeign</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</artifactId>
            </dependency>
        </dependencies>
    </project>

**三、application.yml配置如下：**

spring:
      application:
        name: user
    server:
      port: 28666
    eureka:
      instance:
        #开启IP注册
        prefer-ip-address: true
        #地址名称
        instance-id: ${ spring.cloud.client.ip-address}:${ server.port}
        #心跳
        lease-renewal-interval-in-seconds: 5
        #无心跳，十秒踢出
        lease-expiration-duration-in-seconds: 10
        #获取此实例的相对健康检查URL路径。 健康检查页面URL，然后构造出主机名和通信的类型 - 安全或不安全，如securePort和nonSecurePort规定。 它通常用于制造基于实例的健康做出明智的决策 - 例如，它可以被用来确定是否进行部署到整个服务器场或停止部署，而不会造成进一步的损害。
        health-check-url-path: /actuator/health
      client:
        #表示的频率（以秒为单位）来从eureka服务器注册表的信息
        registryFetchIntervalSeconds: 5
        service-url:
          defaultZone: ${ EUREKA_SERVICE_URL:http://127.0.0.1:28001}/eureka/
    ### Feign 配置
    feign:
      compression:
        request:
          # 开启请求压缩
          enabled: true
          # 配置压缩的 MIME TYPE
          mime-types: text/xml,application/xml,application/json
          # 配置压缩数据大小的下限
          min-request-size: 2048
        response:
          # 开启响应压缩
          enabled: true

**五、我们创建一个接口，MemberServiceFeign.java这是Feign客户端，代码如下：**

@FeignClient(value = "member",fallback = MemberServiceFeignHystric.class)
    public interface MemberServiceFeign { 
    
        /** * 远程调用member接口 * * @param name * @return */
        @GetMapping("/member/sayHiMember")
        String sayHiMember(@RequestParam(value = "name") String name);
    
        /** * 远程调用接口 * * @param name * @return */
        @GetMapping("/member/port")
        String port(@RequestParam(value = "name") String name);
    
    }

**六、我们在User控制器里面调用Feign接口，代码如下：**

@RestController
    @RequestMapping("/user")
    public class UserController { 
        @Resource
        private MemberServiceFeign memberServiceFeign;
        @Value("${server.port}")
        String port;
    
        @GetMapping("/userInfo")
        @ResponseBody
        public String userInfo(@RequestParam String name) { 
            return memberServiceFeign.sayHiMember(name);
        }
    
        @GetMapping("/port")
        @ResponseBody
        public String port(@RequestParam String name) { 
            return memberServiceFeign.port(name);
        }
    }

**七、启动类**

@EnableEurekaClient
    @SpringBootApplication
    @EnableFeignClients
    @EnableDiscoveryClient
    public class ServiceUserApplication { 
    
        public static void main(String[] args) { 
            SpringApplication.run(ServiceUserApplication.class, args);
        }
    
        @Bean
        @LoadBalanced
        RestTemplate restTemplate() { 
            return new RestTemplate();
        }
    }

**八、member服务暴露接口，代码如下：**

@RestController
    @RequestMapping("/member")
    public class MemberController { 
    
        @Value("${server.port}")
        String port;
    
        @GetMapping("/sayHiMember")
        public String sayHiMember(String name) { 
            return "SayHi会员:" + name;
        }
    
        @GetMapping("/port")
        public String port(String name) { 
            return "port:" + port + "名称" + name;
        }
    
    }

**九、使用网页输入地址：127.0.0.1:28666/user/userInfo?name=张三，会展示出SayHi会员:张三，这就说明调用成功了**  
![在这里插入图片描述][20200727141942330.png]

## SpringCloud五大组件之一Feign远程调用已到此结束 ##

[20200727141942330.png]: /images/20230208/a96faa770e5742eb95ee1ec23847dc66.png