OpenFeign 接入 SCA

参考：https://www.mengshuo.top/archives/springcloudnetflix#feign

demo地址：https://duangouyu.coding.net/p/demo/d/SCA/git/tree/openfeign

由于 Feign 也进入了维护, 所以就有了 OpenFeign 这个代替品

Feign 和 OpenFeign 的区别

Feign	OpenFeign
Feign 是 Springcloud 组件中的一个轻量级 Restful 的 HTTP 服务客户端, Feign 内置了 Ribbon, 用来做客户端负载均衡, 去调用服务注册中心的服务. Feign 的使用方式是: 使用 Feign 的注解定义接口, 调用这个接口, 就可以调用服务注册中心的服务.	OpenFeign 是 springcloud 在 Feign 的基础上支持了 SpringMVC 的注解, 如@RequestMapping 等等. OpenFeign 的@FeignClient 可以解析 SpringMVC 的@RequestMapping 注解下的接口, 并通过动态代理的方式产生实现类, 实现类中做负载均衡并调用其他服务.
`<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-feign</artifactId> </dependency>`	`<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-openfeign</artifactId> </dependency>`

OpenFeign 的使用:

微服务调用接口 + @FeignClient 注解

需要注意, @RequesMapping 不能在类名上与@FeignClient 同时使用

如果只有服务消费者添加配置就可以了，服务提供者不调用其他服务可以不用配置，因为底层毕竟还是发起 http 请求

整合 OpenFegin

添加依赖

<!-- 公共依赖 -->
<dependencies>
    <!-- 自定义异常处理 -->
    <dependency>
        <groupId>top.mengshuo</groupId>
        <artifactId>base-exception</artifactId>
    </dependency>
    <!-- 解决 bootstrap.yml 不生效问题  -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-bootstrap</artifactId>
    </dependency>
    <!-- web -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- 端点监控 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
    <!--  Nacos注册中心 -->
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
    </dependency>
    <!-- Nacos配置中心 -->
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
    </dependency>
    <!-- base service -->
    <dependency>
        <groupId>top.mengshuo</groupId>
        <artifactId>base-service</artifactId>
    </dependency>
    <!-- open feign -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-openfeign</artifactId>
    </dependency>
    <!-- loadbalancer -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-loadbalancer</artifactId>
    </dependency>
    <!-- sentinel -->
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
    </dependency>
    <!-- nacos 持久化sentinel规则 -->
    <dependency>
        <groupId>com.alibaba.csp</groupId>
        <artifactId>sentinel-datasource-nacos</artifactId>
    </dependency>
    <!-- 测试 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
        <exclusions>
            <exclusion>
                <groupId>org.junit.vintage</groupId>
                <artifactId>junit-vintage-engine</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
</dependencies>

添加注解启用 OpenFeign

添加 @EnableFeignClients 注解

package top.mengshuo;

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 java.util.Arrays;

/**
 * 服务消费者application
 *
 * @author mengshuo
 * @since 2021-11-17
 */
@EnableFeignClients
@EnableDiscoveryClient
@SpringBootApplication
public class ConsumerServiceApplication {
    public static void main(String[] args) {
        SpringApplication.run(ConsumerServiceApplication.class, args);
    }
}

配置文件启用 Sentinel 和 OpenFeign 的集成

# 启用 sentinel 和 openfeign 集成
feign:
  sentinel:
    enabled: true

代码

服务消费者

添加一个服务调用类

package top.mengshuo.feign;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import top.mengshuo.common.exception.entity.RestResponse;
import top.mengshuo.feign.fallback.ProviderServiceFallback;

/**
 * OpenFeign 声明式客户端
 *
 * @author mengshuo
 * @since 2021-12-12
 */
@FeignClient(name = "provider-service", fallback = ProviderServiceFallback.class, path = "/provider")
public interface ProviderService {

    /**
     * OpenFeign 调用服务提供者
     *
     * @param name 名称
     * @return res
     */
    @PostMapping("/hello")
    RestResponse<?> sayHello(@RequestParam("name") String name);
}

服务降级类

package top.mengshuo.feign.fallback;

import org.springframework.stereotype.Component;
import top.mengshuo.common.exception.entity.RestResponse;
import top.mengshuo.feign.ProviderService;

/**
 * @author mengshuo
 * @since 2021-11-23
 */
@Component
public class ProviderServiceFallback implements ProviderService {

    @Override
    public RestResponse<?> sayHello(String name) {
        return RestResponse.failed().message("OpenFeign 降级");
    }
}

Controller 中调用

package top.mengshuo.controller;

import lombok.extern.log4j.Log4j2;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import top.mengshuo.common.exception.entity.RestResponse;
import top.mengshuo.feign.ProviderService;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

/**
 * @author mengshuo
 * @since 2021-11-17
 */
@Log4j2
@RestController
@RequestMapping("/consumer")
public class ConsumerController {


    @Resource
    private ProviderService providerService;

    @GetMapping("/hello")
    public RestResponse<?> hello(String name) {
        log.info("处理时间：" + LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss:SS")));
        return this.providerService.sayHello(name);
    }

}

服务提供者

添加 service

package top.mengshuo.service.impl;

import com.alibaba.csp.sentinel.annotation.SentinelResource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;
import top.mengshuo.service.ProviderService;

/**
 * @author mengshuo
 * @since 2021-11-17
 */
@SentinelResource
@Service
public class ProviderServiceImpl implements ProviderService {

    @Value("${sys.desc}")
    private String desc;

    /**
     * hello
     *
     * @param name name
     * @return res
     */
    @Override
    public String sayHello(String name) {
        return "hello:" + name + " >>> " + desc;
    }
}

添加 Controller

当没有 name 参数时报错触发服务降级

package top.mengshuo.controller;

import org.springframework.util.ObjectUtils;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import top.mengshuo.common.exception.entity.RestResponse;
import top.mengshuo.service.ProviderService;

import javax.annotation.Resource;

/**
 * @author mengshuo
 * @since 2021-12-12
 */
@RestController
@RequestMapping("/provider")
public class ProviderController {

    @Resource
    private ProviderService providerService;

    @PostMapping("/hello")
    public RestResponse<?> sayHello(String name) {

        if (ObjectUtils.isEmpty(name)) {
            throw new RuntimeException();
        }
        return RestResponse.success().data(this.providerService.sayHello(name));
    }
}

测试

正常调用
缺少参数的调用