小刘学习笔记

创建服务消费者（Feign）

#概述

Feign 是一个声明式的伪 Http 客户端，它使得写 Http 客户端变得更简单。使用 Feign，只需要创建一个接口并注解。它具有可插拔的注解特性，可使用 Feign 注解和 JAX-RS 注解。Feign 支持可插拔的编码器和解码器。Feign 默认集成了 Ribbon，Nacos 也很好的兼容了 Feign，默认实现了负载均衡的效果

  • Feign 采用的是基于接口的注解
  • Feign 整合了 ribbon

#POM

创建一个工程名为 hello-spring-cloud-alibaba-consumer-feign 的服务消费者项目，pom.xml 配置如下：

<?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">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>ml.yompc</groupId>
        <artifactId>hello-spring-cloud-alibaba</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <relativePath>../pom.xml</relativePath>
    </parent>
    <artifactId>hello-spring-cloud-alibaba-consumer</artifactId>
    <packaging>jar</packaging>

    <name>hello-spring-cloud-alibaba-consumer</name>

    <dependencies>
        <!-- Spring Boot Begin -->
        <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-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

        <!-- Spring Boot End -->

        <!-- Spring Cloud Begin -->
        <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>
        <!-- Spring Cloud End -->
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>ml.yompc.hello.spring.cloud.alibaba.consumer.ConsumerApplication</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

主要增加了

		<dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
        </dependency>

Application

通过 @EnableFeignClients 注解开启 Feign 功能

package ml.yompc.hello.spring.cloud.alibaba.consumer;

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

/**
 * @email yom535@outlook.com
 * @author: 有民(yom535)
 * @date: 2019/8/20
 * @time: 20:49
 */
@EnableFeignClients
@EnableDiscoveryClient
@SpringBootApplication
public class ConsumerApplication {
    public static void main(String[] args) {
        SpringApplication.run(ConsumerApplication.class,args);
    }
}

创建 Feign 接口

通过 @FeignClient("服务名") 注解来指定调用哪个服务。代码如下：

package ml.yompc.hello.spring.cloud.alibaba.consumer.service;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;

@FeignClient(name = "hello-spring-cloud-alibaba-provider")
public interface EchoService {
    @GetMapping(value = "/{echo}")
    public String echo(@PathVariable String echo);
}

Controller

package ml.yompc.hello.spring.cloud.alibaba.consumer.controller;

import ml.yompc.hello.spring.cloud.alibaba.consumer.service.EchoService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

/**
 * @email yom535@outlook.com
 * @author: 有民(yom535)
 * @date: 2019/8/20
 * @time: 20:49
 */
@RefreshScope
@RestController
public class FeignEchoController {



    @Autowired
    private EchoService echoService;

    @GetMapping(value = "feign/{echo}")
    public String echo(@PathVariable(value = "echo") String echo){

        return echoService.echo(echo);
    }
}

配置：

bootstrap.yml

spring:
  application:
    name: hello-spring-cloud-alibaba-consumer

  cloud:
    nacos:
      discovery:
        server-addr: 184.172.234.118:30848


server:
  port: 8081

#健康检查
management:
  endpoints:
    web:
      exposure:
        include: "*"

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