什么是feign
这篇文章主要讲解了“什么是feign”,文中的讲解内容简单清晰,易于学习与理解,下面请大家跟着小编的思路慢慢深入,一起来研究和学习“什么是feign”吧!
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 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.8.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.free</groupId> <artifactId>serice-feign</artifactId> <version>0.0.1-SNAPSHOT</version> <name>serice-feign</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> <spring-cloud.version>Greenwich.SR3</spring-cloud.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-client</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-test</artifactId> <scope>test</scope> </dependency> </dependencies> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-dependencies</artifactId> <version>${spring-cloud.version}</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> </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:
server: port: 8765 spring: application: name: service-feign eureka: client: serviceUrl: defaultZone: http://localhost:8761/eureka/
在程序的启动类ServiceFeignApplication ,加上@EnableFeignClients注解开启Feign的功能:
import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.client.discovery.EnableDiscoveryClient; import org.springframework.cloud.openfeign.EnableFeignClients; @SpringBootApplication @EnableDiscoveryClient @EnableFeignClients public class SericeFeignApplication { public static void main(String[] args) { SpringApplication.run(SericeFeignApplication.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:
@Service @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=zz,浏览器交替显示:
hi zz,i am from port:8762
hi zz,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://gitee.com/freesystem/SpringCloudDemo/tree/master/serice-feign
感谢各位的阅读,以上就是“什么是feign”的内容了,经过本文的学习后,相信大家对什么是feign这一问题有了更深刻的体会,具体使用情况还需要大家实践验证。这里是亿速云,小编将为大家推送更多相关知识点的文章,欢迎关注!