[SpringCloud教程]6. OpenFeign远程接口调用

OpenFeign是声明式方式定义Web服务的客户端(说白了就是将原有的url请求调用转化为本地方法调用一样方便快捷)，并可通过集成Ribbon或Eureka实现负载均衡。

• 微服务教程合集: https://www.jianshu.com/c/df2a688e828e
• 案例项目地址: https://gitee.com/spzmmd/spring-cloud-demo

集成

• 在SpringCloud案例项目里建立新模块 ms-consumer-eureka-openfeign，并在父pom里声明，该模块pom.xml如下

    4.0.0
    
        com.spz.demo
        spring-cloud-demo
        1.0-SNAPSHOT
    
    ms-consumer-eureka-openfeign
    jar

    消费者模块 - 使用Eureka注册中心 - 使用OpenFeign客户端

    

        
        
            org.springframework.cloud
            spring-cloud-starter-openfeign
        

        
        
            org.springframework.cloud
            spring-cloud-starter-netflix-eureka-client
        

        
            org.springframework.boot
            spring-boot-starter-actuator
        

        
            com.spz.demo
            api-common
            ${project.version}
        

        
            org.springframework.boot
            spring-boot-starter-web
        

        
            org.projectlombok
            lombok
            true
        

    

    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
                
                    
                        
                            repackage
                        
                    
                
                
                    
                        
                            org.projectlombok
                            lombok
                        
                    
                
            
            
                org.apache.maven.plugins
                maven-compiler-plugin
                
                    1.8
                    1.8
                
            
        
        
            
                src/main/resources
                true
            
        
    

• application.properties 配置如下

server.port=7001

# Eureka
eureka.client.register-with-eureka=false
eureka.client.service-url.defaultZone=http://eureka6001:6001/eureka,http://eureka6002:6002/eureka,http://eureka6003:6003/eureka

# Feign 日志级别
logging.level.com.spz.demo.scloud.consumer.openfeign.service.IEurekaProviderService=debug

# Feign 超时配置
openfeign.connectTimeoutMs=1000
openfeign.readTimeoutMs=5000

• 配置类OpenFeignConfiguration.java

package com.spz.demo.scloud.consumer.openfeign.config;

import com.netflix.ribbon.Ribbon;
import feign.Logger;
import feign.Request;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * OpenFeign 配置
 * @author spzmmd
 * @createTime 2021/04/12
 */
@Configuration
public class OpenFeignConfiguration {

    /**
     * 连接超时
     * 单位: ms
     */
    @Value("${openfeign.connectTimeoutMs}")
    private int connectTimeoutMs;

    /**
     * 读取超时
     * 单位: ms
     */
    @Value("${openfeign.readTimeoutMs}")
    private int readTimeoutMs;

    /**
     * 配置超时时间
     * @return
     */
    @Bean
    public Request.Options options() {
        return new Request.Options(connectTimeoutMs, readTimeoutMs);
    }

    /**
     * 配置OpenFeign输出什么日志， 方便调试
     * @return
     */
    @Bean
    public Logger.Level feignLoggerLevel() {
        return Logger.Level.FULL;
    }
}

• 启动类 ConsumerOpenFeignApp.java

package com.spz.demo.scloud.consumer.openfeign;

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

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

• 通过OpenFeign来实现微服务接口调用的方法是，将接口调用声明为一个个接口方法，如下代码

package com.spz.demo.scloud.consumer.openfeign.service;

import com.spz.demo.scloud.common.core.bean.RestBean;
import com.spz.demo.scloud.consumer.openfeign.config.OpenFeignConfiguration;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.GetMapping;

/**
 * Eureka 服务提供者 接口
 * 用于配置 Feign 接口
 * @author spzmmd
 * @createTime 2021/04/12
 */
@Component
@FeignClient(value = "MS-PROVIDER", configuration = OpenFeignConfiguration.class)
public interface IEurekaProviderService {

    @GetMapping(value = "/projectInfo")
    public RestBean projectInfo();

}

• 测试用的控制器

package com.spz.demo.scloud.consumer.openfeign.controller;

import com.spz.demo.scloud.common.core.bean.RestBean;
import com.spz.demo.scloud.common.service.AppService;
import com.spz.demo.scloud.consumer.openfeign.service.IEurekaProviderService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * 测试 openFeign
 * @author spzmmd
 * @createTime 2021/04/12
 */
@RestController
@RequestMapping("/openFeign")
public class OpenFeignTestController {

    // 使用OpenFeign，实现以接口调用的方式来进行网络请求
    @Autowired
    private IEurekaProviderService eurekaProviderService;

    /**
     * 服务远程调用测试 - 使用 openFeign
     * @return
     */
    @RequestMapping("/projectInfo")
    public RestBean appServiceProjectInfo(){
        RestBean restBean = eurekaProviderService.projectInfo();
        return restBean;
    }
}

• 运行时，需要启动eureka-server(用于服务注册发现) 和两个ms-provider节点，用于测试OpenFeign方式调用微服务接口，而后启动ms-consumer-eureka-openfeign模块，不断访问如下地址:

http://localhost:7001/openFeign/projectInfo

正常应该分别返回两个服务的端口号(OpenFeign默认支持负载均衡)

{
  "code": 2000,
  "message": "MS-PROVIDER:8001: (基于Eureka注册中心)",
  "data": null
}

{
  "code": 2000,
  "message": "MS-PROVIDER:8002: (基于Eureka注册中心)",
  "data": null
}

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