springcloud从入门到实战（看了这篇SpringCloud）
springcloud从入门到实战（看了这篇SpringCloud）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 1 package springcloud.helloworld.eureka.server; 2 3 import org.springframework.boot.SpringApplicat
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>
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application.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>
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
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