Spring Cloud Learning(一): 服务注册

　　官网https://projects.spring.io/spring-cloud/，spring cloud官网各组件版本为：

Component	Edgware.SR4	Finchley.SR1	Finchley.BUILD-SNAPSHOT
spring-cloud-aws	1.2.3.RELEASE	2.0.0.RELEASE	2.0.1.BUILD-SNAPSHOT
spring-cloud-bus	1.3.3.RELEASE	2.0.0.RELEASE	2.0.1.BUILD-SNAPSHOT
spring-cloud-cli	1.4.1.RELEASE	2.0.0.RELEASE	2.0.1.BUILD-SNAPSHOT
spring-cloud-commons	1.3.4.RELEASE	2.0.1.RELEASE	2.0.2.BUILD-SNAPSHOT
spring-cloud-contract	1.2.5.RELEASE	2.0.1.RELEASE	2.0.2.BUILD-SNAPSHOT
spring-cloud-config	1.4.4.RELEASE	2.0.1.RELEASE	2.0.2.BUILD-SNAPSHOT
spring-cloud-netflix	1.4.5.RELEASE	2.0.1.RELEASE	2.0.2.BUILD-SNAPSHOT
spring-cloud-security	1.2.3.RELEASE	2.0.0.RELEASE	2.0.1.BUILD-SNAPSHOT
spring-cloud-cloudfoundry	1.1.2.RELEASE	2.0.0.RELEASE	2.0.1.BUILD-SNAPSHOT
spring-cloud-consul	1.3.4.RELEASE	2.0.1.RELEASE	2.0.2.BUILD-SNAPSHOT
spring-cloud-sleuth	1.3.4.RELEASE	2.0.1.RELEASE	2.0.2.BUILD-SNAPSHOT
spring-cloud-stream	Ditmars.SR4	Elmhurst.SR1	Elmhurst.BUILD-SNAPSHOT
spring-cloud-zookeeper	1.2.2.RELEASE	2.0.0.RELEASE	2.0.1.BUILD-SNAPSHOT
spring-boot	1.5.14.RELEASE	2.0.4.RELEASE	2.0.4.BUILD-SNAPSHOT
spring-cloud-task	1.2.3.RELEASE	2.0.0.RELEASE	2.0.1.BUILD-SNAPSHOT
spring-cloud-vault	1.1.1.RELEASE	2.0.1.RELEASE	2.0.2.BUILD-SNAPSHOT
spring-cloud-gateway	1.0.2.RELEASE	2.0.1.RELEASE	2.0.2.BUILD-SNAPSHOT
spring-cloud-openfeign		2.0.1.RELEASE	2.0.2.BUILD-SNAPSHOT
spring-cloud-function	1.0.0.RELEASE	1.0.0.RELEASE	1.0.1.BUILD-SNAPSHOT

　　其中，在使用spring cloud时，需注意spring boot版本，Finchley构建并使用Spring Boot 2.0.x，预计不会与Spring Boot 1.5.x一起使用。

　　注意：Dalston发布将于2018年12月达到使用寿命.Eginware将遵循Spring Boot 1.5.x的生命周期结束周期。

　　Dalston和Edgware发布版基于Spring Boot 1.5.x构建，预计不会与Spring Boot 2.0.x一起使用。

一、注册与发现

　　Spring Cloud使用eureka,  所有需要访问配置文件的应用都作为一个erureka client注册上去。eureka是一个高可用的组件，它没有后端缓存，每一个实例注册之后需要向注册中心发送请求，在默认情况下erureka server也是一个eureka client ,必须要指定一个 server。

　　maven依赖如下：

<?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.chm</groupId>
    <artifactId>springcloud</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>springcloud</name>
    <description>Spring cloud eureka server project module</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.4.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>
        <spring-cloud.version>Finchley.SR1</spring-cloud.version>
    </properties>

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

    <!-- 使用里程碑版需要下面的配置（Spring官网上的配置更为简洁，
    更适合每个版本 http://projects.spring.io/spring-boot/）。新版本新特性，如开发热部署 -->
    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
    </repositories>

</project>

　　启动类为：

@EnableEurekaServer
@SpringBootApplication
public class SpringcloudEurekaServerApplication {

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

　　　配置文件为：

server:
      port: 9999
eureka:
       instance:
           hostname: 127.0.0.1
       client:
            registerWithEureka: false
            fetchRegistry: false
            serviceUrl:
                     defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

　　结果报异常为：java.lang.IllegalStateException: Failed to load property source from location 'classpath:/application.yml'，需严格注意yml文件格式。

　　启动eureka server，然后访问http://localhost:9999，可看到Eureka启动界面。

客户端

　　maven依赖如下：

 <?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.chm</groupId>
     <artifactId>springcloud</artifactId>
     <version>0.0.1-SNAPSHOT</version>
     <packaging>jar</packaging>

     <name>springcloud</name>
     <description>Spring cloud eureka client project module</description>

     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
         <version>2.0.4.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>
         <spring-cloud.version>Finchley.SR1</spring-cloud.version>
     </properties>

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

     <!-- 使用里程碑版需要下面的配置（Spring官网上的配置更为简洁，
     更适合每个版本 http://projects.spring.io/spring-boot/）。新版本新特性，如开发热部署 -->
     <repositories>
         <repository>
             <id>spring-milestones</id>
             <name>Spring Milestones</name>
             <url>https://repo.spring.io/milestone</url>
             <snapshots>
                 <enabled>false</enabled>
             </snapshots>
         </repository>
     </repositories>

 </project>

　　启动类为：

 @SpringBootApplication
 @EnableEurekaClient
 @RestController
 public class SpringcloudEurekaClientApplication {

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

     @Value("${server.port}")
     String port;
     @RequestMapping("/")
     public String home() {
         return "hello world from port " + port;
     }

 }

　　配置文件为：

 eureka:
   client:
     serviceUrl:
       defaultZone: http://localhost:9999/eureka/
 server:
   port: 8888
 spring:
   application:
     name: service-eurekaclient

　　访问即可发现服务已经注册。