1.  什么是Spring Cloud?

Spring提供了一系列工具,可以帮助开发人员迅速搭建分布式系统中的公共组件(比如:配置管理,服务发现,断路器,智能路由,微代理,控制总线,一次性令牌,全局锁,主节点选举, 分布式session, 集群状态)。协调分布式环境中各个系统,为各类服务提供模板性配置。使用Spring Cloud, 开发人员可以搭建实现了这些样板的应用,并且在任何分布式环境下都能工作得非常好,小到笔记本电脑, 大到数据中心和云平台。

Spring Cloud官网的定义比较抽象,我们可以从简单的东西开始。Spring Cloud是基于Spring Boot的, 最适合用于管理Spring Boot创建的各个微服务应用。要管理分布式环境下的各个Spring Boot微服务,必然存在服务的注册问题。所以我们先从服务的注册谈起。既然是注册,必然有个管理注册中心的服务器,各个在Spring Cloud管理下的Spring Boot应用就是需要注册的client

Spring Cloud使用erureka server,  然后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心跳,在默认情况下erureka server也是一个eureka client ,必须要指定一个 server。

2.  创建Eureka Server

1).创建一个Maven工程helloworld.eureka.server, pom.xml内容如下:

 1 <?xml version="1.0" encoding="UTF-8"?> 
 2 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
 3     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> 
 4   <modelVersion>4.0.0</modelVersion> 
 5   <groupId>com.chry</groupId> 
 6   <artifactId>springcloud.helloworld.eureka.server</artifactId> 
 7   <version>0.0.1-SNAPSHOT</version> 
 8   <packaging>jar</packaging> 
 9   <name>springcloud.helloworld.Eureka.server</name> 
10   <description>Demo Spring Eureka Server</description> 
11  
12     <parent> 
13         <groupId>org.springframework.boot</groupId> 
14         <artifactId>spring-boot-starter-parent</artifactId> 
15         <version>1.5.3.RELEASE</version> 
16         <relativePath/> <!-- lookup parent from repository --> 
17     </parent> 
18  
19     <properties> 
20         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> 
21         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> 
22         <java.version>1.8</java.version> 
23     </properties> 
24  
25     <dependencies> 
26         <!--eureka server --> 
27         <dependency> 
28             <groupId>org.springframework.cloud</groupId> 
29             <artifactId>spring-cloud-starter-eureka</artifactId> 
30         </dependency> 
31         <dependency> 
32             <groupId>org.springframework.cloud</groupId> 
33             <artifactId>spring-cloud-starter-eureka-server</artifactId> 
34         </dependency> 
35         <dependency> 
36             <groupId>org.springframework.cloud</groupId> 
37             <artifactId>spring-cloud-starter-config</artifactId> 
38         </dependency> 
39         <!-- spring boot test--> 
40         <dependency> 
41             <groupId>org.springframework.boot</groupId> 
42             <artifactId>spring-boot-starter-test</artifactId> 
43             <scope>test</scope> 
44         </dependency> 
45     </dependencies> 
46  
47     <dependencyManagement> 
48         <dependencies> 
49             <dependency> 
50                 <groupId>org.springframework.cloud</groupId> 
51                 <artifactId>spring-cloud-dependencies</artifactId> 
52                 <version>Dalston.RC1</version> 
53                 <type>pom</type> 
54                 <scope>import</scope> 
55             </dependency> 
56         </dependencies> 
57     </dependencyManagement> 
58  
59     <build> 
60         <plugins> 
61             <plugin> 
62                 <groupId>org.springframework.boot</groupId> 
63                 <artifactId>spring-boot-maven-plugin</artifactId> 
64             </plugin> 
65         </plugins> 
66     </build> 
67  
68     <repositories> 
69         <repository> 
70             <id>spring-milestones</id> 
71             <name>Spring Milestones</name> 
72             <url>https://repo.spring.io/milestone</url> 
73             <snapshots> 
74                 <enabled>false</enabled> 
75             </snapshots> 
76         </repository> 
77     </repositories> 
78  
79 </project>
pom.xml

 2). 用Spring Boot创建一个服务类EurekaServerApplication,需要一个注解@EnableEurekaServer加在springboot工程的启动类上

 1 package springcloud.helloworld.eureka.server; 
 2  
 3 import org.springframework.boot.SpringApplication; 
 4 import org.springframework.boot.autoconfigure.SpringBootApplication; 
 5 import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer; 
 6  
 7 @EnableEurekaServer 
 8 @SpringBootApplication 
 9 public class EurekaServerApplication { 
10  
11     public static void main(String[] args) { 
12         SpringApplication.run(EurekaServerApplication.class, args); 
13     } 
14 }

3).eureka server的配置文件appication.yml,其中registerWithEureka:false和fetchRegistry:false表明自己是一个eureka server

 1 server: 
 2    port: 8761 
 3  
 4 eureka: 
 5    instance: 
 6        hostname: localhost 
 7    client: 
 8        registerWithEureka: false 
 9        fetchRegistry: false 
10        serviceUrl: 
11            defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

4) eureka server的工程结构如下

5)启动eureka server,然后访问http://localhost:8761, 界面如下, "No instances available" 表示无client注册

 

3.  创建Eureka Client

1). 创建一个Maven工程helloworld.eureka.client, pom.xml内容如下:

 1 <?xml version="1.0" encoding="UTF-8"?> 
 2 <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"> 
 3     <modelVersion>4.0.0</modelVersion> 
 4     <groupId>com.chry</groupId> 
 5     <artifactId>springcloud.helloworld.eureka.client</artifactId> 
 6     <version>0.0.1-SNAPSHOT</version> 
 7     <name>springcloud.helloworld.eureka.client</name> 
 8     <packaging>jar</packaging> 
 9     <description>Demo Spring Boot Client</description> 
10  
11     <parent> 
12         <groupId>org.springframework.boot</groupId> 
13         <artifactId>spring-boot-starter-parent</artifactId> 
14         <version>1.5.3.RELEASE</version> 
15         <relativePath/> <!-- lookup parent from repository --> 
16     </parent> 
17  
18     <properties> 
19         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> 
20         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> 
21         <java.version>1.8</java.version> 
22     </properties> 
23  
24     <dependencies> 
25         <dependency> 
26             <groupId>org.springframework.cloud</groupId> 
27             <artifactId>spring-cloud-starter-eureka</artifactId> 
28         </dependency> 
29         <dependency> 
30             <groupId>org.springframework.boot</groupId> 
31             <artifactId>spring-boot-starter-web</artifactId> 
32         </dependency> 
33  
34         <dependency> 
35             <groupId>org.springframework.boot</groupId> 
36             <artifactId>spring-boot-starter-test</artifactId> 
37             <scope>test</scope> 
38         </dependency> 
39     </dependencies> 
40  
41     <dependencyManagement> 
42         <dependencies> 
43             <dependency> 
44                 <groupId>org.springframework.cloud</groupId> 
45                 <artifactId>spring-cloud-dependencies</artifactId> 
46                 <version>Dalston.RC1</version> 
47                 <type>pom</type> 
48                 <scope>import</scope> 
49             </dependency> 
50         </dependencies> 
51     </dependencyManagement> 
52  
53     <build> 
54         <plugins> 
55             <plugin> 
56                 <groupId>org.springframework.boot</groupId> 
57                 <artifactId>spring-boot-maven-plugin</artifactId> 
58             </plugin> 
59         </plugins> 
60     </build> 
61  
62     <repositories> 
63         <repository> 
64             <id>spring-milestones</id> 
65             <name>Spring Milestones</name> 
66             <url>https://repo.spring.io/milestone</url> 
67             <snapshots> 
68                 <enabled>false</enabled> 
69             </snapshots> 
70         </repository> 
71     </repositories> 
72  
73  
74 </project>
pom.xml

2).  创建主类EurekaClientApplication

使用@EnableEurekaClient注解表明是client

 1 package springcloud.helloworld.eureka.client; 
 2  
 3 import org.springframework.beans.factory.annotation.Value; 
 4 import org.springframework.boot.SpringApplication; 
 5 import org.springframework.boot.autoconfigure.SpringBootApplication; 
 6 import org.springframework.cloud.netflix.eureka.EnableEurekaClient; 
 7 import org.springframework.web.bind.annotation.RequestMapping; 
 8 import org.springframework.web.bind.annotation.RequestParam; 
 9 import org.springframework.web.bind.annotation.RestController; 
10  
11 @SpringBootApplication 
12 @EnableEurekaClient 
13 @RestController 
14  
15 public class EurekaClientApplication { 
16  
17     public static void main(String[] args) { 
18         SpringApplication.run(EurekaClientApplication.class, args); 
19     } 
20  
21     @Value("${server.port}") 
22     String port; 
23     @RequestMapping("/") 
24     public String home() { 
25         return "hello world from port " + port;26     } 
27  
28 }

3) eureka client的配置文件appication.yml

1 eureka: 
2     client: 
3         serviceUrl: 
4             defaultZone: http://localhost:8761/eureka/ 
5 server: 
6     port: 8762 
7 spring: 
8     application: 
9         name: service-helloworld

4). Client启动后, 可以访问http://localhost:8762

 

5). 再次访问服务器端口, 可以看到Service Helloworld已经自动注册到之前的server中

 

下一篇: Spring Cloud 入门教程(二): 配置管理
  • 参考资料:
    • Spring Cloud 官网
    • 博客: http://blog.csdn.net/forezp/article/details/70148833

 

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