openfeign声明式服务调用

前几章讲到了通过Spring Cloud Ribbon和resttemplate实现客户端消费者调用，生产者提供的服务，而Spring Cloud openFeign还提供了一种比Ribbon更简单的服务调用方式 ——— 声明式服务调用

创建openfeign消费者服务cloud-feign-order80

第一步创建pom文件

<?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>springcloud</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloud-feign-order80</artifactId>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!--swagger 整合swagger需要的依赖-->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
        </dependency>
        <!--swagger ui-->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
        </dependency>

        <dependency>
            <groupId>org.example</groupId>
            <artifactId>cloud-api-conmmon</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <!--feign声明式服务的调用-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <fork>true</fork> <!-- fork: 如果没有配置该项配置，devtools不会起作用的，即应用不会restear -->
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

　　创建application.yml文件

server:
  port: 80
spring:
  application:
    name: cloud-order-service
eureka:
  client:
    register-with-eureka: true
    fetch-registry: true
    serviceUrl:
      defaultZone: http://eureka7001.com:7001/eureka/ #集群版

　　编写启动类开启feign功能

package com.shiwen;

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

/**
 * @author wangjie
 * @Title: OpenFeignApplication
 * @Description: openfeign声明式服务的调用
 * @company: 西安石文软件有限公司
 * @date 2020/10/1411:11
 */
@SpringBootApplication
@EnableFeignClients
@EnableEurekaClient
public class OpenFeignApplication {

    public static void main(String[] args) {
        SpringApplication.run(OpenFeignApplication.class,args);
    }
}

　编写controller消费，服务提供者的接口

package com.shiwen.controller;

import com.shiwen.entity.CommonResult;
import com.shiwen.service.FeignService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author wangjie
 * @Title: FeignController
 * @Description: openfeign服务的调用
 * @company: 西安石文软件有限公司
 * @date 2020/10/1411:13
 */
@RestController
@RequestMapping("/order")
public class FeignController {

    @Autowired
    private FeignService feignService;

    @GetMapping("/selete/{id}")
    public CommonResult getUserById(@PathVariable Long id){
        return feignService.selectOne(id);
    }
}

　　使用fegin调用服务提供者的服务就是需要编写对应的service

package com.shiwen.service;

import com.shiwen.entity.CommonResult;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

/**
 * @author wangjie
 * @Title: FeignService
 * @Description: feign接口
 * @company: 西安石文软件有限公司
 * @date 2020/10/1411:19
 */
@FeignClient("CLOUD-PAYMENT-SERVICE") 
public interface FeignService {

    @GetMapping("payment/select-one/{id}")
    CommonResult selectOne(@PathVariable("id") Long id);


}

　service中的　CLOUD-PAYMENT-SERVICE 服务提供者注册到eureka的服务名，@GetMapping("payment/select-one/{id}") 服务提供者的controller接口地址

启动单机版的eureka注册中心

启动cloud-provider-payment8001 和打包启动cloud-provider-payment8001 使用application-8002.yml配置文件启动给注册中心注册两个服务8001，8002

访问http://localhost:80/order/selete/1

再次访问http://localhost:80/order/selete/1

也能实现两个服务的负载均衡调用，因为feign底层使用的还是ribbon的默认的轮巡算法实现负载调用的

openFeign的超时控制，openFeign默认消费者调用是1秒，超过1不在等待，直接报错连接超时

第一步再服务提供方写一个超时的接口

 /**
     * 编写超时程序
     */
    @GetMapping("timeout")
    public CommonResult timeOutMethods(){
        try {
            TimeUnit.SECONDS.sleep(3);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return new CommonResult(200,"超时服务",serverPort);
    }

第二不 openFeign调用服务

@RestController
@RequestMapping("/order")
public class FeignController {

    @Autowired
    private FeignService feignService;

    @GetMapping("/selete/{id}")
    public CommonResult getUserById(@PathVariable Long id){
        return feignService.selectOne(id);
    }

    @GetMapping("/timeout")
    public CommonResult getTimeOut(){
        return feignService.timeOutMethods();
    }
}

@FeignClient("CLOUD-PAYMENT-SERVICE")
public interface FeignService {

    @GetMapping("payment/select-one/{id}")
    CommonResult selectOne(@PathVariable("id") Long id);


    @GetMapping("payment/timeout")
    CommonResult timeOutMethods();


}

配置ribbon的超时时间　

ribbon:
  ConnectTimeout: 5000
  ReadTimeout: 5000
如果没有配置就会报连接超时的错误，配置了消费者调用还会等待

openFeign日志打印功能

日志的级别

配置日志bean

package com.shiwen.config;

import feign.Logger;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * @author wangjie
 * @Title: OpenFeignConfig
 * @Description: feign的日志配置bean
 * @company: 西安石文软件有限公司
 * @date 2020/10/1511:52
 */
@Configuration
public class OpenFeignConfig {

    /**
     * 日志的级别
     * @return
     */
    @Bean
    Logger.Level feignLevel(){
        return Logger.Level.FULL;
    }
}

application.yml开启日志

logging:
  level:
    com.shiwen.config.OpenFeignConfig: debug

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