• Tags         
  • 2018-07-11  19:32:26        
  • 57 °C    

    上一篇文章,讲述了如何通过RestTemplate+Ribbon去消费服务,这篇文章主要讲述如何通过Feign去消费服务。

    一、Feign简介

    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。它具有可插拔的注解特性,可使用Feign 注解和JAX-RS注解。Feign支持可插拔的编码器和解码器。Feign默认集成了Ribbon,并和Eureka结合,默认实现了负载均衡的效果。

    简而言之:

    • Feign 采用的是基于接口的注解
    • Feign 整合了ribbon

    二、准备工作

    继续用上一节的工程, 启动eureka-server,端口为8761; 启动service-hi 两次,端口分别为8762 、8773.

    三、创建一个feign的服务

    新建一个spring-boot工程,取名为serice-feign,在它的pom文件引入Feign的起步依赖spring-cloud-starter-feign、Eureka的起步依赖spring-cloud-starter-eureka、Web的起步依赖spring-boot-starter-web,代码如下:

    <?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">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.forezp</groupId>
    <artifactId>service-feign</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>service-feign</name>
    <description>Demo project for Spring Boot</description>
    <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-eureka</artifactId>
    </dependency>
    <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-feign</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>Dalston.RC1</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>
    <repositories>
    <repository>
    <id>spring-milestones</id>
    <name>Spring Milestones</name>
    <url>https://repo.spring.io/milestone</url>
    <snapshots>
    <enabled>false</enabled>
    </snapshots>
    </repository>
    </repositories>
    </project>
    

    在工程的配置文件application.yml文件,指定程序名为service-feign,端口号为8765,服务注册地址为http://localhost:8761/eureka/ ,代码如下:

    eureka:
    client:
    serviceUrl:
    defaultZone: http://localhost:8761/eureka/
    server:
    port: 8765
    spring:
    application:
    name: service-feign
    

    在程序的启动类ServiceFeignApplication ,加上@EnableFeignClients注解开启Feign的功能:

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

    定义一个feign接口,通过@ FeignClient(“服务名”),来指定调用哪个服务。比如在代码中调用了service-hi服务的“/hi”接口,代码如下:

    /**
    * Created by fangzhipeng on 2017/4/6.
    */
    @FeignClient(value = "service-hi")
    public interface SchedualServiceHi {
    @RequestMapping(value = "/hi",method = RequestMethod.GET)
    String sayHiFromClientOne(@RequestParam(value = "name") String name);
    }
    

    在Web层的controller层,对外暴露一个”/hi”的API接口,通过上面定义的Feign客户端SchedualServiceHi 来消费服务。代码如下:

    @RestController
    public class HiController {
    @Autowired
    SchedualServiceHi schedualServiceHi;
    @RequestMapping(value = "/hi",method = RequestMethod.GET)
    public String sayHi(@RequestParam String name){
    return schedualServiceHi.sayHiFromClientOne(name);
    }
    }
    

    启动程序,多次访问http://localhost:8765/hi?name=forezp,浏览器交替显示:

    hi forezp,i am from port:8762

    hi forezp,i am from port:8763

    Feign源码解析:http://blog.csdn.net/forezp/article/details/73480304

    本文源码下载:
    https://github.com/forezp/SpringCloudLearning/tree/master/chapter3

    五、参考资料

    spring-cloud-feign

    转载自:https://blog.csdn.net/forezp/article/details/69808079

     
    转载请保留页面地址:https://www.breakyizhan.com/springboot/4777.html