SpringCloud Eureka

使用SpringCloud搭建Eureka服務

楊凱傑 2018/04/30 09:00:00

2 7052

使用SpringCloud搭建Eureka服務

簡介	本文將介紹如何使用SpringCloud搭建Eureka-Server及Eureka-Client實現簡單的微服務調用
作者	楊凱傑

1.Eureka簡介

Eureka是Netflix開源的一個RESTful服務，包括Server和Client兩部分，在Spring Cloud子項目Spring Cloud Netflix中。

Eureka服務器是用來當作一個服務註冊中心。Eureka客戶端是一個java客戶端，用來簡化與服務器的交互、作為輪詢負載均衡器，並提供服務的故障切換支持。

2.開始前準備

IntelliJ IDEA
JDK1.8
Maven
SpringBoot版本:1.5.10.RELEASE

3.撰寫程式

(1)搭建Server端

創建一個名稱為eureka-server的Module

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.tp</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>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>1.5.10.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>Edgware.SR2</spring-cloud.version>
   </properties>

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

接者寫一個啟動類，其中@EnableEurekaServer聲明這是一個Eureka服務器

package com.tp;

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

@SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication {

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

最後寫配置文件application.yml，這邊將port設為8888

server:
  port: 8888
eureka:
  instance:
    hostname: localhost
  client:
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

運行EurekaServerApplication.java，成功後打開瀏覽器，輸入localhost:8888，出現下圖及表示已成功啟動服務

(2)搭建Client端(服務提供者)

創建一個名稱為service-provider-01的Module當作服務提供者

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.tp</groupId>
   <artifactId>service-provider-01</artifactId>
   <version>0.0.1-SNAPSHOT</version>
   <packaging>jar</packaging>

   <name>eureka-server</name>
   <description>Demo project for Spring Boot</description>

   <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>1.5.10.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>Edgware.SR2</spring-cloud.version>
   </properties>

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

接這寫啟動類，其中@EnableEurekaClient聲明這是一個Eureka客戶端

package com.tp;

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

@SpringBootApplication
@EnableEurekaClient
public class ServiceProvider01Application {

   public static void main(String[] args) {
      SpringApplication.run(ServiceProvider01Application.class, args);
   }
}

application.yml :

eureka:
  client:
    serviceUrl:
      # 將服務註冊到eureka-server
      defaultZone: http://localhost:8888/eureka/
server:
  port: 8761
spring:
  application:
    name: service-provider

編寫一個TestController

package com.tp.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TestController {
    
    @GetMapping("test")
    public String test() {
        return "test";
    }
}

運行ServiceProvider01Application.java，成功後打開瀏覽器，輸入localhost:8888，可發現該服務已被註冊

(3)搭建Client端(服務調用者)

創建一個名稱為service-invoker的Module當作服務調用者

pom.xml同service-provider-01

application.yml:

eureka:
  client:
    serviceUrl:
      # 將服務註冊到eureka-server
      defaultZone: http://localhost:8888/eureka/
server:
  port: 8762
spring:
  application:
    name: service-invoker

啟動類:

package com.tp;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableEurekaClient
public class ServiceInvokerApplication {

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

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

編寫一個Controller:

package com.tp.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class InvokerController {

    @Autowired
    private RestTemplate restTemplate;

    @GetMapping("router")
    public String router() {
        //這邊會根據名稱(service-provider)去eureka-server取得對應的URL
        String url = "http://service-provider/test";
        return restTemplate.getForObject(url, String.class);
    }

}