​


一 简介

​​微服务注册中心：Consul——概念与基础操作​​介绍了consul的安装和基本操作，本篇开始在consul上进行服务注册与发现，语言使用Java，框架使用Spring Boot整合Consul。

二 Spring Boot整合Consul

通常demo比较好找，导入后观察需要引入哪些依赖，然后启动。最多微调版本和配置问题即可。

2.1 网上demo

打脸来的如此迅速，百度上搜了一堆，最后发现都是官方文档的翻译，版本不清，代码不全，尝试几个未果。再次感叹现在很多文章的质量。

2.2 官方文档

不得已还是先尝试查看官方文档，​​Spring Cloud Consul​​是基于3.0.2版本，给出的集成demo。不过很遗憾，官方给出的sample地址，访问一直是404状态。

微服务注册中心：Consul——服务注册_spring

上面Consul Sample的查看结果：

微服务注册中心：Consul——服务注册_spring_02

2.3 spring-cloud的github

考虑下一种渠道，寻找官方​​github​​。官方的pom.xml配置建议如下：

<project>
<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>{spring-boot-version}</version>
    <relativePath/> <!-- lookup parent from repository -->
  </parent>

  <dependencies>
    <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-consul-discovery</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>
  </dependencies>
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-dependencies</artifactId>
        <version>${spring-cloud.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>
  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>
</project>

事实上，springboot的版本选择过程中也遇到不少问题，几个典型的错误如下（为了节省空间，只截取了关键错误信息）：

2.3.1 启动报错信息1

Description:

An attempt was made to call a method that does not exist. The attempt was made from the following location:

    org.springframework.cloud.client.discovery.health.DiscoveryCompositeHealthIndicator.<init>(DiscoveryCompositeHealthIndicator.java:41)

The following method did not exist:

    org.springframework.boot.actuate.health.CompositeHealthIndicator.<init>(Lorg/springframework/boot/actuate/health/HealthAggregator;)V

The method's class, org.springframework.boot.actuate.health.CompositeHealthIndicator, is available from the following locations:

    jar:file:/Users/lijingyong/.m2/repository/org/springframework/boot/spring-boot-actuator/2.2.6.RELEASE/spring-boot-actuator-2.2.6.RELEASE.jar!/org/springframework/boot/actuate/health/CompositeHealthIndicator.class

It was loaded from the following location:

    file:/Users/lijingyong/.m2/repository/org/springframework/boot/spring-boot-actuator/2.2.6.RELEASE/spring-boot-actuator-2.2.6.RELEASE.jar


Action:

Correct the classpath of your application so that it contains a single, compatible version of org.springframework.boot.actuate.health.CompositeHealthIndicator


Process finished with exit code 1


2.3.2 报错2

Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.cloud.consul.serviceregistry.ConsulAutoRegistration]: Factory method 'consulRegistration' threw exception; nested exception is java.lang.IllegalArgumentException: Consul service ids must not be empty, must start with a letter, end with a letter or digit, and have as interior characters only letters, digits, and hyphen: null
  at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
  at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:651) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
  ... 96 common frames omitted
Caused by: java.lang.IllegalArgumentException: Consul service ids must not be empty, must start with a letter, end with a letter or digit, and have as interior characters only letters, digits, and hyphen: null
  at org.springframework.cloud.consul.serviceregistry.ConsulAutoRegistration.normalizeForDns(ConsulAutoRegistration.java:178) ~[spring-cloud-consul-discovery-2.2.1.RELEASE.jar:2.2.1.RELEASE]

2.4 一个可用demo

根据官方说明，并参考另一个demo：https://github.com/RobbieXie/springboot-consul 后，整理如下，不过是使用的较旧版本springboot，可以根据需要更新到适合的版本信息。

关键配置和代码：

2.4.1 pom.xml

<?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>

    <groupId>org.example</groupId>
    <artifactId>springboot-consul</artifactId>
    <description>Spring Boot整合consul示例</description>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.9.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>com.orbitz.consul</groupId>
            <artifactId>consul-client</artifactId>
            <version>1.0.0</version>
        </dependency>
        <dependency>
            <groupId>com.ecwid.consul</groupId>
            <artifactId>consul-api</artifactId>
            <version>1.3.0</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

    <repositories>
        <repository>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
            <id>central</id>
            <name>bintray</name>
            <url>http://jcenter.bintray.com</url>
        </repository>
    </repositories>
</project>

2.4.2 应用启动类 SpringBootConsulApplication

package com.flamingskys.learn.springboot.consul;

import com.flamingskys.learn.springboot.consul.service.ConsulService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;

import javax.annotation.PreDestroy;

@SpringBootApplication
@EnableAutoConfiguration
public class SpringBootConsulApplication {

    @Value("${consul.instanceId}")
    private String instanceId;

    @Bean
    public String getInstanceId(){
        return instanceId;
    }

    @Autowired
    private ConsulService consulService;

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

    @PreDestroy
    public void beforeExit(){
        System.out.println("-----------------------------BEFORE  EXIT--------------------------------");
        consulService.deregisterService(instanceId);
    }
}

2.4.3 资源配置application.properties

spring.application.name=first-consul-client

consul.host=127.0.0.1
consul.port=8500
consul.instanceId=${spring.application.name}:${spring.application.instanceid:${random.value}}

spring.cloud.consul.discovery.heartbeat.enabled=true


应用启动后，查看console上注册的服务列表，first-consul-client就是我们的服务：

微服务注册中心：Consul——服务注册_spring boot_03


完整代码已上传到了​​gitee​​。可关注公众号：程序员架构进阶 随时获取更新。