Spring Cloud Alibaba学习（五）：服务消费者-Feign

Feign能够让我们以更优雅的方式发起调用，并且集成了robbin负载均衡。

创建consumer-feign子模块

pom.xml

主要引入的feign相关依赖：spring-cloud-starter-openfeign

<?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>
        <artifactId>spring-cloud-alibaba-icydate</artifactId>
        <groupId>com.icydate</groupId>
        <version>1.0.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>consumer-feign</artifactId>

    <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>
        <!-- Spring Boot Begin -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- Spring Boot End -->

        <!-- Spring Cloud Begin -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <!-- Spring Cloud End-->
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.icydate.ConsumerFeignApplication</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

application.yml

spring:
  application:
    name: icydate-feign-consumer
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848

server:
  port: 8083

SpringBoot启动类

添加@EnableFeignClients来启用Feign客户端

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

Feign接口

使用@FeignClient("服务提供者名")来指定要调用的Provider

接口写法与Controller类似，不过Feign接口是发送请求

@FeignClient("icydate-provider")
public interface FeignService {

    @GetMapping(value = "/get/{caller}")
    String getPort(@PathVariable String caller);

}

Controller接口

@RestController
public class NacosFeignConsumerController {

    @Autowired
    FeignService feignService;

    // 同样取到配置文件中的应用名
    @Value("${spring.application.name}")
    private String appName;

    @GetMapping(value = "/call/provider")
    public String callProvider() {
        // 调用feign接口
        return feignService.getPort(appName);
    }
}

目录结构

启动项目后，访问/call/provider，得到如下返回