简单教你一招玩转consul作为springcloud的服务注册中心

---

一、consul的下载安装

consul的下载地址：https://www.consul.io/downloads

解压之后

在该路径下以cmd的方式打开
然后启动

consul agent -dev

二、框架搭建

1、创建父工程

删除src目录

2、创建服务提供子模块(provider-consul-module)

3、创建服务消费子模块(consumer-consul-module)

二、代码准备

1、父工程pom

<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>4.0.0modelVersion>

    <groupId>com.cloudgroupId>
    <artifactId>springcloud_allartifactId>
    <version>1.0-SNAPSHOTversion>
    <modules>
        <module>provider-consul-modulemodule>
        <module>consumer-consul-modulemodule>
    modules>
    <packaging>pompackaging>
    <properties>
        <project.build.sourceEncoding>UTF-8project.build.sourceEncoding>
        <maven.compiler.source>1.8maven.compiler.source>
        <maven.compiler.target>1.8maven.compiler.target>
        <junit.version>4.13junit.version>
        <log4j.version>1.2.17log4j.version>
        <lombok.version>1.16.18lombok.version>
        <mysql.version>8.0.19mysql.version>
        <druid.version>1.2.4druid.version>
        <mybatis.spring.boot.version>2.1.4mybatis.spring.boot.version>
        <druid.spring.boot.version>1.2.4druid.spring.boot.version>
        <springfox-swagger-ui.version>2.9.2springfox-swagger-ui.version>
        <springfox-swagger2.version>2.9.2springfox-swagger2.version>
    properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-dependenciesartifactId>
                <version>2.4.3version>
                <type>pomtype>
                <scope>importscope>
            dependency>
            
            <dependency>
                <groupId>org.springframework.cloudgroupId>
                <artifactId>spring-cloud-dependenciesartifactId>
                <version>2020.0.2version>
                <type>pomtype>
                <scope>importscope>
            dependency>
            
            <dependency>
                <groupId>com.alibaba.cloudgroupId>
                <artifactId>spring-cloud-alibaba-dependenciesartifactId>
                <version>2021.1version>
                <type>pomtype>
                <scope>importscope>
            dependency>
            <dependency>
                <groupId>mysqlgroupId>
                <artifactId>mysql-connector-javaartifactId>
                <version>${mysql.version}version>
            dependency>
            <dependency>
                <groupId>com.alibabagroupId>
                <artifactId>druidartifactId>
                <version>${druid.version}version>
            dependency>
            <dependency>
                <groupId>org.mybatis.spring.bootgroupId>
                <artifactId>mybatis-spring-boot-starterartifactId>
                <version>${mybatis.spring.boot.version}version>
            dependency>
            <dependency>
                <groupId>com.alibabagroupId>
                <artifactId>druid-spring-boot-starterartifactId>
                <version>${druid.spring.boot.version}version>
            dependency>
            <dependency>
                <groupId>io.springfoxgroupId>
                <artifactId>springfox-swagger-uiartifactId>
                <version>${springfox-swagger-ui.version}version>
            dependency>
            <dependency>
                <groupId>io.springfoxgroupId>
                <artifactId>springfox-swagger2artifactId>
                <version>${springfox-swagger2.version}version>
            dependency>
        dependencies>
    dependencyManagement>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-maven-pluginartifactId>
                <configuration>
                    <fork>truefork>
                    <addResources>trueaddResources>
                configuration>
            plugin>
        plugins>
    build>
project>

2、服务提供子模块pom

<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>springcloud_allartifactId>
        <groupId>com.cloudgroupId>
        <version>1.0-SNAPSHOTversion>
    parent>
    <modelVersion>4.0.0modelVersion>

    <groupId>com.providergroupId>
    <artifactId>provider-consul-moduleartifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>

        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-consul-discoveryartifactId>
        dependency>

        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-actuatorartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-devtoolsartifactId>
        dependency>
        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
        dependency>
    dependencies>
project>

3、消费服务子模块pom

<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>springcloud_allartifactId>
        <groupId>com.cloudgroupId>
        <version>1.0-SNAPSHOTversion>
    parent>
    <modelVersion>4.0.0modelVersion>

    <groupId>com.consumergroupId>
    <artifactId>consumer-consul-moduleartifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-consul-discoveryartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-actuatorartifactId>
        dependency>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-devtoolsartifactId>
        dependency>
        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
        dependency>
    dependencies>
project>

4、提供服务模块和消费模块服务模块启动类

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

@SpringBootApplication
@EnableDiscoveryClient
public class ConsulConsumerApplication {
     

    public static void main(String[] args) {
     
        SpringApplication.run(ConsulConsumerApplication.class, args);
    }
}

@EnableDiscoveryClient注解的作用：能够让注册中心能够发现，扫描到微服务。

5、提供服务模块和消费模块服务模块application.yml文件

server:
  port: 8006
spring:
  cloud:
    consul:
      host: 127.0.0.1
      port: 8500
      discovery:
        service-name: ${
     spring.application.name}
  application:
    name: provider-consul-module

server:
  port: 80
spring:
  application:
    name: consumer-consul-module
  cloud:
    consul:
      host: 127.0.0.1
      port: 8500
      discovery:
        service-name: ${
     spring.application.name}

6、提供服务模块和消费模块服务模块controller代码

@RestController
@Slf4j
public class ProviderConsulController {
     
    @Value("${server.port}")
    private String serverPort;

    @GetMapping(value = "/provider/test")
    public String test() {
     
        return "提供服务模块服务端口号为:" + serverPort + "《--------------》" + UUID.randomUUID().toString();
    }
}

@RestController
public class ConsumerConsulController {
     
    private static final String INVOKE_URL = "http://provider-consul-module";

    @Resource
    private RestTemplate restTemplate;

    @GetMapping(value = "/consumer/test")
    public String getData() {
     

        return restTemplate.getForObject(INVOKE_URL + "/provider/test", String.class);
    }
}

7、RestTemplate详解及其配置

RestTemplate是spring封装的一个服务端远程HTTP请求工具，支持常见的Rest请求（get、post等）
简单了说就是用来远程调用的，因为你订单模块是一个服务，消费模块又是一个单独的服务，两个服务端的端口号要进行交互，所以就有了RestTemplate

当然要注入RestTemplate(注意是在消费模块配置，因为是消费服务调用提供服务模块）

@Configuration
public class ApplicationContextConfig {
     

    @Bean
    @LoadBalanced
    public RestTemplate AutoRestTemplate() {
     
        return new RestTemplate();
    }
}

三、测试

启动提供服务模块和消费服务模块（注意一定要开启zookeeper服务，顺便进入zookeeper客户端）

访问http://localhost:8500，你可以看到consul的客户端界面（然后我们启动的两个服务已经成功注册进consul）

接口测试

成功！

四、灵魂拷问？为什么需要注册中心

我们在微服务中首先需要面对的问题是服务之间如何进行通信呢？在单体架构中，我们只要将服务的接口暴露，然后通过http请求即可，微服务当然也可以这样。
问题是我们请求的url是固定的，单体服务为我们还可以很快的修改；一旦有大量的服务那就需要我们手动维护服务接口，配置负载均衡；服务宕机后，如何及时下线呢？
总而言之注册中心必不可少（至少当前时代是这样）。