Spring Cloud Alibaba 教程 | Nacos 篇

Spring Cloud Alibaba 教程 | Nacos 篇

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写在前面的话： 本笔记在参考网上视频以及博客的基础上，只做个人学习笔记，如有侵权，请联系删除，谢谢！

1、使用nacos做服务的注册和发现

1、父工程项目pom

<dependencyManagement>
    <dependencies>
	
    <dependency>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-dependenciesartifactId>
                <version>2.1.2.RELEASEversion>
                <type>pomtype>
                <scope>importscope>
      dependency>
    
    <dependency>
        <groupId>org.springframework.cloudgroupId>
        <artifactId>spring-cloud-dependenciesartifactId>
        <version>Greenwich.SR2version>
        <type>pomtype>
        <scope>importscope>
    dependency>
    
    <dependency>
        <groupId>com.alibaba.cloudgroupId>
        <artifactId>spring-cloud-alibaba-dependenciesartifactId>
        <version>2.1.0.RELEASEversion>
        <type>pomtype>
        <scope>importscope>
    dependency>
    dependencies>
dependencyManagement>

2、nacos-provider 工程Pom文件

<dependencies>
    <dependency>
        <groupId>org.projectlombokgroupId>
        <artifactId>lombokartifactId>
        <version>1.18.0version>
        <optional>trueoptional>
    dependency>
    <dependency>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-webartifactId>
    dependency>
    <dependency>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-testartifactId>
        <scope>testscope>
    dependency>
    
    <dependency>
        <groupId>com.alibaba.cloudgroupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discoveryartifactId>
    dependency>
dependencies>

​ YAML文件配置

server:
  port: 8081
  servlet:
    context-path: /nacos-provider

spring:
  application:
    name: nacos-provider
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848

​ 服务提供类

import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/sayHello")
public class HelloController {
    @RequestMapping("/test/{name}")
    public String sayHello(@PathVariable("name") String name){
        return "nihao! " + name;
    }
}

3、nacos-consumer pom文件配置

<dependencies>
        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
            <version>1.18.0version>
            <optional>trueoptional>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>
        
        <dependency>
            <groupId>com.alibaba.cloudgroupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discoveryartifactId>
        dependency>
    dependencies>

​ YAML配置

server:
  port: 8082

spring:
  application:
    name: nacos-consumer
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848

消费类

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

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

    /**
     * 创建RestTemplate并注入Spring容器
     */
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}

/**********************调用服务测试**************/


import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
@RequestMapping("hello")
public class ConsumerController {

    @Autowired
    public RestTemplate restTemplate;

    @RequestMapping("sayHi/{name}")
    public String sayHello(@PathVariable("name") String name){
        return restTemplate.getForObject("http://nacos-provider/nacos-provider/sayHello/test/" +name, String.class);
    }

}

网页端测试：

http://localhost:8082/hello/sayHi/zhngsan

2、使用nacos做配置管理

微服务要拉取nacos中管理的配置，并且与本地的application.yml配置合并，才能完成项目启动。

但如果尚未读取application.yml，又如何得知nacos地址呢？

因此spring引入了一种新的配置文件：bootstrap.yaml文件，会在application.yml之前被读取，流程如下：

​

在nacos中新建配置

1. 在需要抽取配置到nacos中的工程中引入nacos-config依赖配置：

<dependency>
    <groupId>com.alibaba.cloudgroupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-configartifactId>
dependency>

2. 添加bootstrap.yaml

   spring:
     application:
       name: nacos-provider # 服务名称
     profiles:
       active: dev #开发环境，这里是dev
     cloud:
       nacos:
         discovery:
           server-addr: 192.168.192.128:8848
         config:
           server-addr: 192.168.192.128:8848 # Nacos地址
           file-extension: yaml  # 文件后缀名
   

   使用

   ${spring.application.name}-${spring.profiles.active}.${spring.cloud.nacos.config.file-extension}作为文件id，来读取配置。即nacos-provider-dev.yaml

​ 3、读取nacos配置

@Value("${pattern.dateformat}")
private String dateFormater;

@RequestMapping("getConfig")
public String getConfig(){
    return DateTimeFormatter.ofPattern(dateFormater).format(LocalDateTime.now());
}

2、1配置热更新

上面的步骤简单实现了读取nacos上的配置，还未实现配置的热更新。

要实现配置热更新，可以使用两种方式：

1、在@Value注入的变量所在类上添加注解@RefreshScope：

@RefreshScope
public class HelloController {
    
    @Value("${pattern.dateformat}")
    private String dateFormater;
}

2、使用@ConfigurationProperties注解的配置类代替@Value注解。

​ 创建配置类：

​

 
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

@Component
@ConfigurationProperties(prefix = "pattern")
public class PaternProperties {
    private String dateformat;

    public String getDateformat() {
        return dateformat;
    }

    public void setDateformat(String dateformat) {
        this.dateformat = dateformat;
    }
}

使用nacos配置

@Autowired
private PaternProperties paternProperties;

@RequestMapping("getConfig")
public String getConfig(){
    return DateTimeFormatter.ofPattern(paternProperties.getDateformat()).format(LocalDateTime.now());
}