Spring Cloud 之 OpenFeign

前言

OpenFeign 全称 Spring Cloud OpenFeign，它是 Spring 官方推出的一种声明式服务调用与负载均衡组件。我们可以像调用本地方法一样来调用远程服务，而完全感觉不到这是在进行远程调用。

1、常用注解

使用 OpenFegin 进行远程服务调用时，常用注解如下表。

2、实践

2.1、修改pom.xml配置

在上一章节 【《微服务实战》 第五章】 基础上，添加OpenFeign依赖项

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.hqyj</groupId>
        <artifactId>SpringCloud</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <artifactId>customer-api</artifactId>
    <name>customer-api</name>
    <description>customer-api</description>

    <properties>
        <java.version>1.8</java.version>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <dependencies>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--devtools 开发工具-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <!--Spring Boot 测试-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!--junit 测试-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <!-- 修改后立即生效，热部署 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>springloaded</artifactId>
            <version>1.2.8.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-loadbalancer -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <dependency>
            <groupId>com.hqyj</groupId>
            <artifactId>common-api</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
    </dependencies>

</project>

2.2、增加用户服务接口，添加FeignClient配置

import com.hqyj.common.model.UserInfo;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import java.util.List;

/***
 * @title 用户服务接口
 * @desctption 用户服务接口
 * @author kelvin
 * @create 2023/5/11 16:44
 **/
@Component
@FeignClient(value = "USER-SERVICE")
public interface UserService {<!-- -->
    @RequestMapping(value = "/user/userInfoList",method = RequestMethod.GET)
    public List&lt;UserInfo&gt; userInfoList();
}

2.3、修改控制层UserConsumerController

import com.hqyj.common.model.UserInfo;
import com.hqyj.customerapi.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;

/***
 * @title UserConsumerController
 * @desctption 用户控制层
 * @author kelvin
 * @create 2023/5/11 14:22
 **/
@RestController
@RequestMapping("/user")
public class UserConsumerController {<!-- -->

/*    @Autowired
    private UserConsumerService userConsumerService;*/

    @Autowired
    private UserService userService;

    @GetMapping("/userInfoList")
    public List&lt;UserInfo&gt; userInfoList(){<!-- -->
        return userService.userInfoList();
    }
}

2.4、启动类增加OpenFeign配置

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

/***
 * @title SpringBoot 启动类
 * @desctption SpringBoot 启动类
 * @author kelvin
 * @create 2023/5/11 12:22
 **/
@SpringBootApplication
@EnableFeignClients
public class CustomerApiApplication {<!-- -->

    public static void main(String[] args) {<!-- -->
        SpringApplication.run(CustomerApiApplication.class, args);
    }

}

2.5、远程调用超时设置

openFeign其实是有默认的超时时间的，默认分别是连接超时时间10秒、读超时时间60秒 可添加配置，自定义超时时间

server:
  port: 80

eureka:
  client:
    register-with-eureka: false #本微服务为服务消费者，不需要将自己注册到服务注册中心
    fetch-registry: true  #本微服务为服务消费者，需要到服务注册中心搜索服务
    service-url:
      defaultZone: http://localhost:7001/eureka
feign:
  client:
    config:
      default:
        #建立连接所用的时间，适用于网络状况正常的情况下，两端连接所需要的时间
        connect-timeout: 5000
        #指建立连接后从服务端读取到可用资源所用的时间
        read-timeout: 10000