SpringCloud 从入门到精通 14---OpenFeign 服务调用

关注

发布于: 2021 年 01 月 21 日

在SpringCloud 从入门到精通 09--- 支付服务集群中,我们通过使用RestTemplate进行了服务的调用,本节我们使用更优雅的方式OpenFeign来实现基于接口的微服务调用.本节内容较多,不会一一的把每个服务中的内容都写清楚,所以如果有不明白的地方,可以看前几章,也可以在下放留言交流.

本节需准备三个项目

cloud-alibaba-payment-9001
cloud-alibaba-payment-9002
cloud-alibaba-order-8000

这三个项目在之前的章节中有相关的代码,现在我们使用nacos作为服务注册中心、配置中心,把cloud-alibaba-payment-9001 cloud-alibaba-payment-9002 cloud-alibaba-order-8000都注册进入nacos集群,通过cloud-alibaba-order-8000来访问cloud-alibaba-payment-9001 和 cloud-alibaba-payment-9002,并实现负载均衡.

之前,我们采用的是注入RestTemplate实现微服务的调用,现在引入了OpenFeign后,就不再采用它了,首先在pom.xml中引入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>cloudservice</artifactId>        <groupId>com.felix</groupId>        <version>1.0-SNAPSHOT</version>    </parent>    <modelVersion>4.0.0</modelVersion>
    <artifactId>cloud-alibaba-order-8000</artifactId>
    <dependencies>        <dependency>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-starter-web</artifactId>        </dependency>        <dependency>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-starter-actuator</artifactId>        </dependency>        <dependency>            <groupId>com.felix</groupId>            <artifactId>cloud-mbg</artifactId>        </dependency>        <dependency>            <groupId>com.felix</groupId>            <artifactId>cloud-common</artifactId>        </dependency>        <dependency>            <groupId>org.springframework.cloud</groupId>            <artifactId>spring-cloud-starter-openfeign</artifactId>        </dependency>        <dependency>            <groupId>com.alibaba.cloud</groupId>            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>        </dependency>        <dependency>            <groupId>com.alibaba.cloud</groupId>            <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>        </dependency>    </dependencies></project>

复制代码

注释掉ApplicationContextConfig

//package com.felix.order.config;////import org.springframework.cloud.client.loadbalancer.LoadBalanced;//import org.springframework.context.annotation.Bean;//import org.springframework.context.annotation.Configuration;//import org.springframework.web.client.RestTemplate;////@Configuration//public class ApplicationContextConfig {//    @Bean//    @LoadBalanced//    public RestTemplate restTemplate(){//        return new RestTemplate();//    };//}

复制代码

增加service包,新增PaymentService

package com.felix.order.service;

import com.felix.common.result.CommonResult;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;import org.springframework.web.bind.annotation.PostMapping;
@Component@FeignClient(value = "cloud-alibaba-payment")public interface PaymentService {    @PostMapping(value = "/payment/create")    CommonResult createPayment(String serialNo);
    @GetMapping(value = "/payment/{id}")    CommonResult getPayment(@PathVariable(value = "id") Long id);
    @GetMapping(value = "/payment/timeout")    CommonResult timeout();}

复制代码

这里,我们添加了@FeignClient(value = "cloud-alibaba-payment")注解,不同于之前的项目,我们采用http://的形式引入微服务的名称,大家可以把这个注解理解为相同的逻辑,指明我们将要使用OpenFeign进行微服务的调用.请注意,这里的@PostMapping(value = "/payment/create") @GetMapping(value = "/payment/{id}") @GetMapping(value = "/payment/timeout")与cloud-alibaba-payment-9001的接口请求方式和接口uri是对应的,这里贴一下cloud-alibaba-payment-9001的PaymentController中的内容

package com.felix.payment.controller;
import com.felix.common.result.CommonResult;import com.felix.payment.service.CPaymentService;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.*;
import javax.annotation.Resource;
@Controller@RequestMapping("/payment")public class PaymentController {    @Resource    private CPaymentService paymentService;
    @PostMapping(value = "/create")    @ResponseBody    public CommonResult createPayment(String serialNo){        return paymentService.createPayment(serialNo);    }
    @GetMapping(value = "/{id}")    @ResponseBody    public CommonResult getPayment(@PathVariable Long id){        return paymentService.getPayment(id);    }
    @GetMapping(value = "/timeout")    @ResponseBody    public CommonResult timeout(){        return paymentService.timeout();    }}

复制代码

这里新增了一个timeout的接口,其实现是

 @Override    public CommonResult timeout() {        try {            TimeUnit.SECONDS.sleep(3);        } catch (InterruptedException e) {            e.printStackTrace();        }        return new CommonResult(200,"操作成功，当前服务是:payment"+port,"success",null);    }

复制代码

只进行了 3 秒的线程 sleep,大家先添加好,后面针对应用场景进行说明

回到cloud-alibaba-order-8000,有了PaymentService接口,我们直接在OrderController中按照常规的方式去写

package com.felix.order.controller;
import com.felix.common.result.CommonResult;import com.felix.order.service.PaymentService;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.*;
import javax.annotation.Resource;
@Controller@RequestMapping("/order")public class OrderController {
    @Resource    private PaymentService paymentService;
    @PostMapping(value = "/payment/create")    @ResponseBody    public CommonResult createPayment(String serialNo){        return paymentService.createPayment(serialNo);    }
    @GetMapping(value = "/payment/{id}")    @ResponseBody    public CommonResult getPayment(@PathVariable Long id){        return paymentService.getPayment(id);    }
    @GetMapping(value = "/payment/timeout")    @ResponseBody    public CommonResult timeout(){        return paymentService.timeout();    }}

复制代码

这里PaymentService没有实现,其实现由OpenFeign帮我们实现,我们只需要注入PaymentService然后使用即可,现在,项目目录如下ApplicationContextConfig是全部注释掉了,所以显示的图标如此

然后,配置CloudOrderApplication开启对于OpenFeign的使用

package com.felix.order;
import feign.Logger;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cloud.client.discovery.EnableDiscoveryClient;import org.springframework.cloud.openfeign.EnableFeignClients;import org.springframework.context.annotation.Bean;

@SpringBootApplication@EnableDiscoveryClient@EnableFeignClientspublic class CloudOrderApplication {    public static void main(String[] args) {        SpringApplication.run(CloudOrderApplication.class,args);    }
    @Bean    Logger.Level feignLoggerLevel(){        return Logger.Level.FULL;    }}

复制代码

解释一下这里注入的feignLoggerLevel,目的是用来对OpenFeign所作的请求进行的日志输出级别的定义.

然后,配置一下bootstrap.yml

spring:  application:    name: cloud-alibaba-order-comsumer  cloud:    nacos:      discovery:        server-addr: localhost:8847      config:        server-addr: localhost:8847        file-extension: yaml        group: PROD_GROUP        namespace: 0ca7333d-533c-4fdf-9860-f1fb69b9edc6
ribbon:  ReadTimeout: 60000 #等待服务器处理的超时时间  ConnectTimeout: 2000  #建立 socket 连接所需要的超时时间

server:  port: 8000
management:  endpoints:    web:      exposure:        include: '*'
logging:  level:    com.felix.order.service.PaymentService: debug

复制代码

这里spring.cloud.nacos.config的内容,如果在nacos中没有进行配置,那么这里可以忽略不写.然后ribbon中定义了ReadTimeout和ConnectTimeout的超时时间,为什么呢?

OpenFeign 自带了 Ribbon,Ribbon 在进行服务调用的时候,默认超时时间为 1S,所以,按照我们在 cloud-alibaba-payment-9001 的/payment/timeout 接口中进行了 3 秒的延时操作,会直接导致 Ribbon 的调用超时,进而报错,为了避免这种情况,就需要在 OpenFeign 的服务中,针对超时的时间进行定义

接下来,启动cloud-alibaba-payment-9001 cloud-alibaba-payment-9002 cloud-alibaba-order-8000,然后多次访问http://localhost:8000/order/payment/1,不仅可以正常的返回信息,而且实现了负载均衡