服务注册中心的简单介绍和使用

服务注册中心一般原理说明:

服务提供者启动
服务提供者将相关服务信息主动注册到注册中心
服务消费者采用poll模式主动拉取(定时拉取)可用的服务提供者清单
服务消费者也可以直接调用服务提供者

注册中心需要完成服务提供者的健康监控，当发现服务提供者失效时需要及时剔除

注册中心对比

C:数据一致性

A:高可用性

P:分区容错性(必须满足的)

服务注册中心组件eureka

eureka基础架构

eureka的服务端:eureka注册中心

eureka的客户端:服务消费者，服务提供者

eureka项目启动出现如下问题

Caused by: java.lang.NoClassDefFoundError: org/springframework/cloud/context/environment/EnvironmentChangeEvent

子项目中缺少如下

使用https://start.spring.io/actuator/info，找到springboot和springcloud对应的版本

eureka配置集群方案

第一步修改本地电脑host

127.0.0.1 LagouCloudEurekaServerA
127.0.0.1 LagouCloudEurekaServerB

第二步

#eureka server服务端口号
server.port=8761
 
#应用名称
spring.application.name=eureka-service
 
#当前eureka的实例名
eureka.instance.hostname=LagouCloudEurekaServerA
#配置eureka客户端交互的地址
eureka.client.service-url.defaultZone=http://LagouCloudEurekaServerB:8762/eureka
#是否注册到eureka
eureka.client.register-with-eureka=true
#不需要获取服务提供者信息
eureka.client.fetch-registry=true
 
spring.main.allow-bean-definition-overriding=true
 
 
logging.level.com.eureka=info
logging.level.web=info
spring.devtools.add-properties=false
 
 
 
#eureka server服务端口号
server.port=8762
 
#应用名称
spring.application.name=first-eureka
 
#当前eureka的实例名
eureka.instance.hostname=LagouCloudEurekaServerB
#配置eureka客户端交互的地址
eureka.client.service-url.defaultZone=http://LagouCloudEurekaServerA:8761/eureka
#是否注册到eureka
eureka.client.register-with-eureka=true
#不需要获取服务提供者信息
eureka.client.fetch-registry=true
 
spring.main.allow-bean-definition-overriding=true
 
 
logging.level.com.eureka=info
logging.level.web=info
spring.devtools.add-properties=false

服务提供者集群

server.port=1000
 
spring.application.name=first-provider
#注册到eureka注册中心,如果是注册到集群就用逗号连接多个，单实例写上一个就好
eureka.client.service-url.defaultZone=http://LagouCloudEurekaServerB:8762/eureka,http://LagouCloudEurekaServerA:8761/eureka
 
 
logging.level.first.provider=debug
logging.level.web=debug
spring.devtools.add-properties=false
 
 
server.port=1001
 
spring.application.name=first-provider
#注册到eureka注册中心,如果是注册到集群就用逗号连接多个，单实例写上一个就好
eureka.client.service-url.defaultZone=http://LagouCloudEurekaServerB:8762/eureka,http://LagouCloudEurekaServerA:8761/eureka
 
 
logging.level.second.provider=debug
logging.level.web=debug
spring.devtools.add-properties=false

　创建消费者

server.port=2000
 
spring.application.name=one-consumer
#注册到eureka注册中心,如果是注册到集群就用逗号连接多个，单实例写上一个就好
eureka.client.service-url.defaultZone=http://LagouCloudEurekaServerB:8762/eureka,http://LagouCloudEurekaServerA:8761/eureka
 
 
logging.level.one.consumer=debug
logging.level.web=debug
spring.devtools.add-properties=false

<dependencies>
    <!--客户端-->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    </dependency>
    <!--web依赖-->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
 
    </dependencies>
 
package one.consumer;
 
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
 
/**
 * @author yourheart
 * @Description
 * @create 2022-04-04 14:40
 */
@SpringBootApplication
@EnableDiscoveryClient
public class OneConsumerApplication {
    public static void main(String[] args) {
        SpringApplication.run(OneConsumerApplication.class,args);
    }
}
 
 
package one.consumer.config;
 
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;
import org.springframework.web.client.RestTemplate;
 
/**
 * @author yourheart
 * @Description
 * @create 2022-04-04 15:05
 */
@Component
public class RestTemplateConfig {
 
    @Bean
    public RestTemplate getRestTemplste(){
        return new RestTemplate();
    }
}
 
 
package one.consumer.controller.front;
 
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.client.RestTemplate;
 
/**
 * @author yourheart
 * @Description
 * @create 2022-04-05 22:38
 */
@Controller
public class ConsumerController {
 
    @Autowired
    private RestTemplate restTemplate;
 
    @RequestMapping("/queryIpCity/{ip}")
    @ResponseBody
    public String queryIpCity(@PathVariable String ip){
 
        String forObject = restTemplate.getForObject("http://localhost:1000/queryIpCity/" + ip, String.class);
 
 
        return "消费调用返回结果:"+forObject;
    }
}

消费者从注册中心获取实例

package one.consumer.controller.front;
 
 
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.client.RestTemplate;
 
import java.util.List;
 
/**
 * @author yourheart
 * @Description
 * @create 2022-04-05 22:38
 */
@Controller
public class ConsumerController {
 
 
    @Autowired
    private DiscoveryClient discoveryClient;
 
    @Autowired
    private RestTemplate restTemplate;
 
 
 
    /**
     * 从注册中心获取服务实例
     * @param ip
     * @return
     */
    @RequestMapping("/queryIpCityFromEureka/{ip}")
    @ResponseBody
    public String queryIpCityFromEureka(@PathVariable String ip){
 
        List<ServiceInstance> instances = discoveryClient.getInstances("FIRST-PROVIDER");
        ServiceInstance instance = instances.get(0);
        String host = instance.getHost();
        int port = instance.getPort();
        String url="http://"+host+":"+port+"/queryIpCity/" + ip;
 
        String forObject = restTemplate.getForObject(url, String.class);
 
 
        return "从注册中心获取服务实例,消费调用返回结果:"+forObject;
    }
}

　　父类依赖

<?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>pingan.parent</groupId>
    <artifactId>pingan-parent</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>eureka-service</module>
        <module>first-eureka</module>
        <module>first-provider</module>
        <module>second-provider</module>
        <module>one-consumer</module>
    </modules>
 
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.0.RELEASE</version>
        <relativePath/>
    </parent>
 
    <!--这里是为了统一控制版本-->
    <dependencyManagement>
        <dependencies>
            <!--引入springcloud版本-->
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Hoxton.SR12</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
 
 
 
        </dependencies>
    </dependencyManagement>
 
 
</project>

　　服务器提供者

<?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">
    <parent>
        <artifactId>pingan-parent</artifactId>
        <groupId>pingan.parent</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
 
    <groupId>first.provider</groupId>
    <artifactId>first-provider</artifactId>
 
    <dependencies>
        <!--客户端-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <!--web依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
 
    </dependencies>
 
 
</project>
server.port=1000
 
spring.application.name=first-provider
#注册到eureka注册中心,如果是注册到集群就用逗号连接多个，单实例写上一个就好
eureka.client.service-url.defaultZone=http://LagouCloudEurekaServerB:8762/eureka,http://LagouCloudEurekaServerA:8761/eureka
 
 
logging.level.first.provider=debug
logging.level.web=debug
spring.devtools.add-properties=false
 
 
package first.provider;
 
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
/**
 * @author yourheart
 * @Description
 * @create 2022-04-02 23:05
 */
@SpringBootApplication
@EnableDiscoveryClient
public class FirstProviderApplication {
    public static void main(String[] args) {
        SpringApplication.run(FirstProviderApplication.class,args);
    }
}
 
 
package first.provider.controller.front;
 
 
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
 
/**
 * @author yourheart
 * @Description
 * @create 2022-04-02 23:08
 */
@Controller
public class FirstController {
 
    @RequestMapping("/queryIpCity/{ip}")
    @ResponseBody
    public String queryIpCity(@PathVariable String ip){
        return ip;
    }
}