1.spring服务注册和发现

2.编译条件

JDK 1.8 or later
Gradle 4+ or Maven 3.2+

3.代码格式

3.1 service目录

3.2 client的目录

4.POM.xml的文件

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>2.2.2.RELEASE</version>
      <relativePath/> <!-- lookup parent from repository -->
   </parent>
   <groupId>com.example</groupId>
   <artifactId>service-registration-and-discovery-service</artifactId>
   <version>0.0.1-SNAPSHOT</version>
   <name>service-registration-and-discovery-service</name>
   <description>Demo project for Spring Boot</description>

   <properties>
      <java.version>1.8</java.version>
      <spring-cloud.version>Hoxton.SR1</spring-cloud.version>
   </properties>

   <dependencies>
      <dependency>
         <groupId>org.springframework.cloud</groupId>
         <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
      </dependency>

      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-test</artifactId>
         <scope>test</scope>
         <exclusions>
            <exclusion>
               <groupId>org.junit.vintage</groupId>
               <artifactId>junit-vintage-engine</artifactId>
            </exclusion>
         </exclusions>
      </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>

   <repositories>
      <repository>
         <id>spring-milestones</id>
         <name>Spring Milestones</name>
         <url>https://repo.spring.io/milestone</url>
      </repository>
   </repositories>

</project>

build.gradle

plugins {
   id 'org.springframework.boot' version '2.2.2.RELEASE'
   id 'io.spring.dependency-management' version '1.0.8.RELEASE'
   id 'java'
}

group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '1.8'

repositories {
   mavenCentral()
   maven { url 'https://repo.spring.io/milestone' }
}

ext {
   set('springCloudVersion', "Hoxton.SR1")
}

dependencies {
   implementation 'org.springframework.cloud:spring-cloud-starter-netflix-eureka-server'
   testImplementation('org.springframework.boot:spring-boot-starter-test') {
      exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
   }
}

dependencyManagement {
   imports {
      mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
   }
}

test {
   useJUnitPlatform()
}

5.原理

启动Eureka服务注册表
您首先需要一个Eureka服务注册中心。

可以使用Spring Cloud的@EnableEurekaServer来建立一个注册表，其他应用程序可以与之通信。

这是一个常规的Spring引导应用程序，添加了一个注释（@enableeruekaserver）以启用服务注册表

5.1 启动EurekaServer的服务

@EnableEurekaServer
@SpringBootApplication

package com.example.serviceregistrationanddiscoveryservice;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@EnableEurekaServer
@SpringBootApplication
public class ServiceRegistrationAndDiscoveryServiceApplication {

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

5.2 启动Client的客户端

@EnableDiscoveryClient
@SpringBootApplication

定义一个Client的客服端

package com.example.serviceregistrationanddiscoveryclient;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
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.RestController;

import java.util.List;

@EnableDiscoveryClient
@SpringBootApplication
public class ServiceRegistrationAndDiscoveryClientApplication {

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

@RestController
class ServiceInstanceRestController {

   @Autowired
   private DiscoveryClient discoveryClient;

   @RequestMapping("/service-instances/{applicationName}")
   public List<ServiceInstance> serviceInstancesByApplicationName(
         @PathVariable String applicationName) {
      return this.discoveryClient.getInstances(applicationName);
   }
}

5.3配置为

server.port=8761

eureka.client.register-with-eureka=false
eureka.client.fetch-registry=false

logging.level.com.netflix.eureka=OFF
logging.level.com.netflix.discovery=OFF

5.4 测试应用程序

5.4.1 要使用Maven运行Eureka服务，请在终端窗口（在/complete目录中）中运行以下命令：

./mvnw spring-boot:run -pl eureka-service

下载老半天，不好用，修改为, 本机也配置了mvn环境，

mvn spring-boot:run -pl eureka-service

编译成功后，启动界面为：启动服务端口为8761端口，

2020-04-06 19:42:12.075 INFO 4075 --- [ Thread-11] o.s.c.n.e.server.EurekaServerBootstrap : Initialized server context
2020-04-06 19:42:12.100 INFO 4075 --- [ Thread-11] e.s.EurekaServerInitializerConfiguration : Started Eureka Server
2020-04-06 19:42:12.139 INFO 4075 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8761 (http) with context path ''
2020-04-06 19:42:12.140 INFO 4075 --- [ main] .s.c.n.e.s.EurekaAutoServiceRegistration : Updating port to 8761
2020-04-06 19:42:12.144 INFO 4075 --- [ main] gistrationAndDiscoveryServiceApplication : Started ServiceRegistrationAndDiscoveryServiceApplication in 19.956 seconds (JVM running for 20.472)