SpringCloud——服務的註冊與發現Eureka
一、spring cloud簡介
Spring Cloud為開發人員提供了快速構建分散式系統中一些常見模式的工具(例如配置管理,服務發現,斷路器,智慧路由,微代理,控制匯流排)。分散式系統的協調導致了樣板模式, 使用Spring Cloud開發人員可以快速地支援實現這些模式的服務和應用程式。他們將在任何分散式環境中執行良好,包括開發人員自己的膝上型電腦,裸機資料中心,以及Cloud Foundry等託管平臺。
特性
Spring Cloud專注於提供良好的開箱即用經驗的典型用例和可擴充套件性機制覆蓋。
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分散式/版本化配置
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服務註冊和發現
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路由
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service - to - service呼叫
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負載均衡
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斷路器
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分散式訊息傳遞
二、 建立服務註冊中心(eureka-server)
是採用Eureka作為服務註冊與發現的元件
1 、首先建立一個maven主工程
首先建立一個主Maven工程,在其pom檔案引入依賴,spring Boot版本為2.0.4.RELEASE,Spring Cloud版本為Finchley.RELEASE。
父pom.xml 檔案:
<?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.example.demo</groupId> <artifactId>springcloud-eureka</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>pom</packaging> <name>springcloud-eureka</name> <description>Demo project for Spring Boot</description> <modules> <module>eureka-server</module> <module>eureka-client</module> </modules> <parent> <groupId>com.example</groupId> <artifactId>springcloud-master</artifactId> <version>0.0.1-SNAPSHOT</version> </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.RELEASE</spring-cloud.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</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> </project>
2 、建立兩個model工程,分別為eureka-server和eureka-cient:
2.1、eureka-server的pom.xml檔案:
<?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.example.demo.eureka</groupId> <artifactId>eureka-server</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>eureka-server</name> <description>Demo project for Spring Boot</description> <parent> <groupId>com.example.demo</groupId> <artifactId>springcloud-eureka</artifactId> <version>0.0.1-SNAPSHOT</version> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <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> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
2.2、註冊中心啟動類,添加註解@EnableEurekaServer,表明自己是一個eurekaserver.
package com.example.demo.eureka;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
@EnableEurekaServer
@SpringBootApplication
public class EurekaServerApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaServerApplication.class, args);
}
}
2.3、eureka是沒有後端快取的,每一個例項註冊之後需要向註冊中心傳送心跳,在預設情況下erureka server也是一個eureka client ,所以必須要指定一個 server。
eureka-server的配置檔案appication.yml:
server:
port: 8081
eureka:
instance:
hostname: localhost
client:
fetch-registry: false
register-with-eureka: false
serviceUrl:
defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
spring:
application:
name: eureka-server
注意:通過eureka.client.fetch-registry: false:false和eureka.client.fetch-registry:false來表明自己是一個eureka server.
No application available 沒有服務被發現 ,因為沒有註冊服務。
三、建立一個服務提供者 (eureka-client)
建立過程同server類似,建立完pom.xml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.example.demo.erueka</groupId>
<artifactId>eureka-client</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>eureka-client</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>com.example.demo</groupId>
<artifactId>springcloud-eureka</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<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-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
啟動類添加註解@EnableEurekaClient 表明自己是一個eurekaclient.
package com.example.demo.erueka;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@SpringBootApplication
@EnableEurekaClient
@RestController
public class EurekaClientApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaClientApplication.class, args);
}
@Value("${server.port}")
private String port;
@GetMapping("/test")
public String test(String name){
return name + "============="+port;
}
}
還需要在配置檔案中註明自己的服務註冊中心的地址,application.yml配置檔案如下:
server:
port: 8082
spring:
application:
name: eureka-client
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8081/eureka/
# fetch-registry: false
# register-with-eureka: false
注意:需要指明spring.application.name,因為在以後的服務與服務之間相互呼叫一般都是根據這個name 。
這會你發現一個服務已經註冊在服務中了,服務名為SERVICE-CLIENT ,埠為8082
張三=============8082