[Java知识库]9.OpenFeign服务接口调用

学习B站尚硅谷周阳老师SpringCloud的听课笔记

1. 概述

1.1 OpenFeign是什么？

Feign是一个声明式的web服务客户端，让编写web服务客户端变得非常容易，只需创建一个接口并在接口上添加注解即可

GitHub：https://github.com/spring-cloud/spring-cloud-openfeign

1.2 能干嘛

1.3Feign和OpenFeign两者区别

2.OpenFeign使用步骤

2.1 新建cloud-consumer-feign-order80

Feign在消费端使用
接口+注解 微服务调用接口+@FeignClient

2.2 改pom

<?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>cloud2020</artifactId>
        <groupId>com.atguigu.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloud-consumer-feign-order80</artifactId>

    <!--openfeign-->
    <dependencies>
        <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>
        <dependency>
            <groupId>com.atguigu.springcloud</groupId>
            <artifactId>cloud-api-common</artifactId>
            <version>${project.version}</version>
        </dependency>
        <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>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>

2.3改yml

server:
  port: 80
eureka:
  client:
    register-with-eureka: false
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka, http://eureka7002.com:7002/eureka

2.4 主启动类标注注解@EnableFeignClients

@SpringBootApplication
@EnableFeignClients
public class OrderFeignMain80 {
    public static void main(String[] args) {
        SpringApplication.run(OrderFeignMain80.class,args);
    }
}

2.5 业务类

业务逻辑接口+@FeignClient配置调用provider服务

新建PaymentFeignService接口并新增注解@FeignClient

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

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

@RestController
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);
    }
}

2.6 测试

先启动2个eureka集群7001/7002，再启动2个微服务8001/8002，启动OpenFeign启动

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

Feign自带负载均衡配置项

总结：

3.OpenFeign超时控制和日志打印功能

3.1超时控制

OpenFeign默认等待一秒钟，超过后报错

OpenFeign默认支持Ribbon

YML文件里需要开启OpenFeign客户端超时控制，即ribbon的超时控制

ribbon:
  ReadTimeout:  5000 # 建立连接后从服务器读取可用资源所用的时间
  ConnectTimeout: 5000 #建立连接需要的时间，适用于网络状况正常的情况下，两端连接所用的时间

3.2日志打印

日志级别：

写配置类

@Configuration
public class FeignConfig {
    @Bean
    Logger.Level feignLoggerLevel(){
        return Logger.Level.FULL;
    }
}

改yml

logging:
  level:
    com.atguigu.springcloud.service.PaymentFeignService: debug

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