SpringCloud Nacos服务注册与发现

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简介

Nacos致力于帮助您发现、配置和管理微服务。Nacos提供了一组简单易用的特性集，帮助您快速实现动态服务发现、服务配置、服务元数据及流量管理。Nacos帮助您更敏捷和容易地构建、交付和管理微服务平台。Nacos是构建以“服务”为中心的现代应用架构 (例如微服务范式、云原生范式) 的服务基础设施。
在接下里的教程中，将使用Nacos作为微服务架构中的注册中心

  • 1、Nacos 下载地址：https://github.com/alibaba/nacos/releases
  • 2、执行如下命令启动Nacos：cmd startup.cmd -m standalone
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  • 3、在浏览器中打开Nacos提供的管理页面(用户名，密码为 nacos 可配置 )
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Nacos 服务提供者

搭建工程

  • 引入maven依赖

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    <?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>com.lutao</groupId>
        <artifactId>nacos-client</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>nacos-client</name>
        <description>Demo project for nacos</description>

        <properties>
            <java.version>1.8</java.version>
            <nacos.version>0.2.1.RELEASE</nacos.version>
            <spring-boot.version>2.0.4.RELEASE</spring-boot.version>
            <spring-cloud.version>Finchley.RELEASE</spring-cloud.version>
        </properties>

        <dependencyManagement>
            <dependencies>
                <dependency>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-dependencies</artifactId>
                    <version>${spring-boot.version}</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
                <dependency>
                    <groupId>org.springframework.cloud</groupId>
                    <artifactId>spring-cloud-dependencies</artifactId>
                    <version>${spring-cloud.version}</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
            </dependencies>
        </dependencyManagement>

        <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>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
                <version>${nacos.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
                <version>${nacos.version}</version>
            </dependency>
        </dependencies>

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

    </project>

  • application.properties中添加相关配置

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    server.port=8070
    spring.application.name=example
    spring.cloud.nacos.discovery.server-addr=127.0.0.1:8848

  • 添加服务启动代码，并对外提供服务

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    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RestController;

    @SpringBootApplication
    @EnableDiscoveryClient
    public class NacosClientApplication {

        public static void main(String[] args) {
            SpringApplication.run(NacosClientApplication.class, args);
        }
        @RestController
        class EchoController {
            @RequestMapping(value = "/echo/{string}", method = RequestMethod.GET)
            public String echo(@PathVariable String string) {
                return "Hello Nacos Discovery " + string;
            }
        }
    }

  • 启动服务提供者之后会在nacos的管理页面中看到nacos-provider相关的服务信息

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Nacos 服务消费者

搭建工程

  • 引入maven依赖

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    <?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>com.lutao</groupId>
        <artifactId>nacos-consumer</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>nacos-consumer</name>
        <description>Demo project for Spring Boot</description>

        <properties>
            <java.version>1.8</java.version>
            <nacos.version>0.2.1.RELEASE</nacos.version>
            <spring-boot.version>2.0.4.RELEASE</spring-boot.version>
            <spring-cloud.version>Finchley.RELEASE</spring-cloud.version>
        </properties>

        <dependencyManagement>
            <dependencies>
                <dependency>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-dependencies</artifactId>
                    <version>${spring-boot.version}</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
                <dependency>
                    <groupId>org.springframework.cloud</groupId>
                    <artifactId>spring-cloud-dependencies</artifactId>
                    <version>${spring-cloud.version}</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
            </dependencies>
        </dependencyManagement>
        <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>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
                <version>${nacos.version}</version>
            </dependency>
        </dependencies>

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

    </project>

  • application.properties中添加相关配置

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    server.port=8080
    spring.application.name=service-consumer
    spring.cloud.nacos.discovery.server-addr=127.0.0.1:8848

  • 服务消费者可以根据服务名远程调用服务提供者提供的接口

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    package com.lutao.nacosconsumer;

    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.DiscoveryClient;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.cloud.client.loadbalancer.LoadBalanced;
    import org.springframework.context.annotation.Bean;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RestController;
    import org.springframework.web.client.RestTemplate;

    @SpringBootApplication
    @EnableDiscoveryClient
    public class NacosConsumerApplication {
        @LoadBalanced
        @Bean
        public RestTemplate restTemplate() {
            return new RestTemplate();
        }
        public static void main(String[] args) {
            SpringApplication.run(NacosConsumerApplication.class, args);
        }
        @RestController
        public class TestController {

            private final RestTemplate restTemplate;

            @Autowired(required=true)
            private DiscoveryClient discoveryClient;

            @Autowired
            public TestController(RestTemplate restTemplate) {this.restTemplate = restTemplate;}

            @RequestMapping(value = "/echo/{str}", method = RequestMethod.GET)
            public String echo(@PathVariable String str) {
                return restTemplate.getForObject("http://example/echo/" + str, String.class);
            }
            /**
             * 获取所有服务
             */
            @RequestMapping("/services")
            public Object services() {
                return discoveryClient.getInstances("example");
            }
        }
    }

通过调用http://127.0.0.1:8080/echo/nacosclient即可获取到服务提供者提供的数据信息

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通过调用http://127.0.0.1:8080/services可以看到Nacos中提供的相关的服务的信息，存储的信息很简单类似Eureka注册中心

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Nacos 注意事项

兼容版本

SpringCloud SpringBoot Spring Cloud Alibaba
Greenwich 2.1.x 0.2.2(还没有RELEASE)
Finchley 2.0.x 0.2.1
Edgware 1.5.x 0.1.1
Dalston 1.5.x 0.1.1

在SpringBoot 2.0.x以下时 Spring Cloud Alibaba为0.1.1 启动报错

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2019/06/11 15:10:30 INFO  [main] [org.springframework.boot.autoconfigure.logging.AutoConfigurationReportLoggingInitializer] : 

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2019/06/11 15:10:30 ERROR [main] [org.springframework.boot.SpringApplication] : Application startup failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'nacosAutoServiceRegistration' defined in class path resource [org/springframework/cloud/alibaba/nacos/NacosDiscoveryAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.cloud.alibaba.nacos.registry.NacosAutoServiceRegistration]: Factory method 'nacosAutoServiceRegistration' threw exception; nested exception is java.lang.NoSuchMethodError: org.springframework.cloud.client.serviceregistry.AbstractAutoServiceRegistration.<init>(Lorg/springframework/cloud/client/serviceregistry/ServiceRegistry;Lorg/springframework/cloud/client/serviceregistry/AutoServiceRegistrationProperties;)V
	at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:599)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1173)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1067)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543)
	at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122)
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693)
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:303)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107)
	at cn.zhangfusheng.alibaba.nacos.test.server.AlibabaNacosTestServerApplication.main(AlibabaNacosTestServerApplication.java:21)
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.cloud.alibaba.nacos.registry.NacosAutoServiceRegistration]: Factory method 'nacosAutoServiceRegistration' threw exception; nested exception is java.lang.NoSuchMethodError: org.springframework.cloud.client.serviceregistry.AbstractAutoServiceRegistration.<init>(Lorg/springframework/cloud/client/serviceregistry/ServiceRegistry;Lorg/springframework/cloud/client/serviceregistry/AutoServiceRegistrationProperties;)V
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:189)
	at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:588)
	... 18 common frames omitted
Caused by: java.lang.NoSuchMethodError: org.springframework.cloud.client.serviceregistry.AbstractAutoServiceRegistration.<init>(Lorg/springframework/cloud/client/serviceregistry/ServiceRegistry;Lorg/springframework/cloud/client/serviceregistry/AutoServiceRegistrationProperties;)V
	at org.springframework.cloud.alibaba.nacos.registry.NacosAutoServiceRegistration.<init>(NacosAutoServiceRegistration.java:43)
	at org.springframework.cloud.alibaba.nacos.NacosDiscoveryAutoConfiguration.nacosAutoServiceRegistration(NacosDiscoveryAutoConfiguration.java:62)
	at org.springframework.cloud.alibaba.nacos.NacosDiscoveryAutoConfiguration$$EnhancerBySpringCGLIB$$5cdf832e.CGLIB$nacosAutoServiceRegistration$2(<generated>)
	at org.springframework.cloud.alibaba.nacos.NacosDiscoveryAutoConfiguration$$EnhancerBySpringCGLIB$$5cdf832e$$FastClassBySpringCGLIB$$531121d8.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228)
	at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:358)
	at org.springframework.cloud.alibaba.nacos.NacosDiscoveryAutoConfiguration$$EnhancerBySpringCGLIB$$5cdf832e.nacosAutoServiceRegistration(<generated>)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:162)
	... 19 common frames omitted
Disconnected from the target VM, address: '127.0.0.1:52284', transport: 'socket'

Process finished with exit code 1

查看源码_如图报错

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  • NacosAutoServiceRegistration 继承 AbstractAutoServiceRegistration,AbstractAutoServiceRegistration的构造函数值接收一个ServiceRegistry serviceRegistry

解决问题

  • 查看 AbstractAutoServiceRegistration 所在的依赖关系

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  • 限定 spring-cloud-Commons的版本号.当前的1.3.0 版本中AbstractAutoServiceRegistration的构造函数接收单个参数

通过dependencyManagement限制版本

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<dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Edgware.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>0.1.1.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
           <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-commons</artifactId>
                <version>1.3.5.RELEASE</version>
            </dependency>
        </dependencies>
    </dependencyManagement>
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