从零开始搭建微服务5: feign

1、feign调用流程,消费端调用feign,feign查询注册中心服务提供者,进行负载调用

2、创建一个服务端，一个消费端，一个feign-api

3、启动之前的eureka服务

4、新建模块feign-inherit-api，统一管理feign接口

<dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            <version>2.2.3.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-openfeign -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
            <version>2.2.2.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-web -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

5、新建一个接口类，添加feign注解，指定需要查找的服务

FeignClient注解表明这是一个负载feign，value就是需要查询的服务提供端在eureka中的注册名

@FeignClient(value = "feign-inherit-provide")
public interface UserRemoteClient {
    @GetMapping("/user/name")
    public String getName();
}

6、新建消费者模块，并pom文件引用feign-api

 <dependencies>
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>feign-inherit-api</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>

7、新建启动类，因为feign接口不在这个模块中，所以需要通过basePackages指定feign路径

@SpringBootApplication
@EnableFeignClients(basePackages = {"com.wujun"})
@EnableDiscoveryClient
public class ConsumeApp {
    public static void main(String[] args) {
        SpringApplication.run(ConsumeApp.class,args);
    }
}

8、新建配置文件，指定eureka地址等

server.port=8088
eureka.client.service-url.defaultZone = http://wujun:123456@127.0.0.1:8761/eureka/

9、新建controller，调用feign接口

@RestController
public class DemoController {
    @Resource
    UserRemoteClient userRemoteClient;

    @GetMapping("/call")
    public String callHello() {
        String name = userRemoteClient.getName();
        return "调用结果" + name;
    }
}

10、启动项目

11、新建消费者模块feign-inherit-provide，并引用feign-api

<dependencies>
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>feign-inherit-api</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>

12、新建配置文件，配置eureka注册地址等

spring.application.name=feign-inherit-provide
server.port=8087
eureka.client.service-url.defaultZone = http://wujun:123456@127.0.0.1:8761/eureka/

13、新建controller实现feign接口

@RestController
public class DemoController implements UserRemoteClient {
    public String getName() {
        return "wujun8787";
    }
}

14、新建启动类

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

15、分别分配两个端口，启动provider，测试consumer接口,接口负载正常使用

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