Kite的学习历程SpringCloud之OpenFeign的客户端的创建使用

Kite学习历程的第二十二天

1. OpenFeign的服务调用

其特点：
声明式REST客户端：Feign创建一个用JAX-RS或Spring MVC注释修饰的接口的动态实现

1.1 创建OpenFeign的客户端cloud-consumer-feign-order-81

1.1.1 通过pom.xml引入依赖

相比ribbon多引入了：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>demo01cloud</artifactId>
        <groupId>cn.kitey.spring</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloud-consumer-feign-order-81</artifactId>

    <dependencies>
        <!--openfeign依赖的引入-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <!--引入自己创建的entities包-->
        <dependency>
            <groupId>cn.kitey.spring</groupId>
            <artifactId>cloud-api-commons</artifactId>
            <version>${project.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--监控-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <!--热部署-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId><!-- -->
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

</project>

1.1.2 创建application.yml配置文件

注册中心还是Eureka注册中心

server:
  port: 81
eureka:
  client:
    register-with-eureka: false
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka/, http://eureka7002.com:7002/eureka/

1.1.3 创建主启动类

注意：
添加注解：
@EnableFeignClients：表示这个是OpenFeign的客户端

package cn.kitey.springcloud;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableFeignClients
public class OrderFeignMain81 {
    public static void main(String[] args) {
        SpringApplication.run(OrderFeignMain81.class, args);
    }
}

1.1.4 创建service接口

注意注解：

1. @FeignClient(value = “CLOUD-PAYMENT-SERVICE”)：表示连接注册中心服务端的名称
2. 其中的方法要与在服务端的方法保持一致，以及getmapping类容也要保持一致

package cn.kitey.springcloud.service;

import cn.kitey.springcloud.entities.CommonResult;
import cn.kitey.springcloud.entities.Payment;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

@Component
@FeignClient(value = "CLOUD-PAYMENT-SERVICE")
public interface PaymentFeignService {

    @GetMapping(value = "/payment/get/{id}")
    CommonResult<Payment> getPaymentById (@PathVariable("id") Long id);

}

1.1.5 创建controller类

1. 通过创建接口对象：paymentFeignService
2. 调用其getPaymentById 方法，进行服务端的控制

package cn.kitey.springcloud.controller;

import cn.kitey.springcloud.entities.CommonResult;
import cn.kitey.springcloud.entities.Payment;
import cn.kitey.springcloud.service.PaymentFeignService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;

@RestController
@Slf4j
public class OrderFeignController {

    @Resource
    private PaymentFeignService paymentFeignService;

    @GetMapping(value = "/consumer/payment/get/{id}")
    public CommonResult<Payment> getPaymentById(@PathVariable("id") Long id){
        return paymentFeignService.getPaymentById(id);
    }
}

1.2 进行测试

启动Eureka的集群注册中心7001，7002，然后启动服务端8001，8002，然后启动81的客户端
Eureka注册中心：

通过访问：
http://localhost:81/consumer/payment/get/4
获取服务端的信息

或者http://localhost:81/consumer/payment/get/3

以上就完成了OpenFeign客户端的创建！