如何實現一個簡單的微服務例子 SpringBoot+Eureka+ribbon+maven

SpringBoot：開發框架

Eureka：註冊中心

ribbon: 實現負載均衡

maven: 管理項目

1、首先簡單描述一下此微服務結構圖：

2、創建的詳細流程：

1）註冊中心Eureka服務端實現：

1、 start.spring.io 去找模板，自己加依賴EurekaServer

2、在eclipse中創建SpringBoot項目，結構如圖：（jdk版本不一致還需要自己去修改，本文不作詳細描述）

3、將pom.xml文件內容替換成剛剛下載的sd-Eureka-server.zip中pom.xml（需要提前配置好maven）

本文pom文件參考如下： jar包下載完成，項目中多了Maven Dependenties目錄。

<?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>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.6.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.example</groupId>
	<artifactId>sd-Eureka-Server</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>sd-Eureka-Server</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>1.8</java.version>
		<spring-cloud.version>Greenwich.SR1</spring-cloud.version>
	</properties>

	<dependencies>
		<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>

	<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>

4、添加啓動類，啓動Eureka註冊中心

在java路徑下創建包com.example，包內創建類EurekaServerRunApp.java，內容如下：

（其實也可以把剛sd-Eureka-server.zip 中src目錄直接替換，這裏我自己寫的，正好複習下）

EurekaServerRunApp.java

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;
//啓動Eureka服務
@EnableEurekaServer
@SpringBootApplication
public class EurekaServerRunApp {
	public static void main(String[] args) {
		SpringApplication.run(EurekaServerRunApp.class, args);
	}
}

5、在resources目錄下添加配置文件application.yml，內容如下：

security:
  basic:
    enabled: true
  user:
    name: user
    password: password123

server:
  port: 8761

eureka:
  client:
    register-with-eureka: false
    fetch-registry: false
    service-url:
      defaultZone: http://user:password123@localhost:8761/eureka

logging:
  level:
    root: INFO

6、接下來就是啓動服務，網頁中查看效果了，如圖：

啓動：

網頁輸入：http://localhost:8761/

到此，Eureka服務端創建並啓動完成！

2）接下來我們創建服務提供者1（項目名稱：provider-user1）

1、也是到 Start.spring.io去下載模板，這次選擇的依賴有兩個 EurekaClient，Web 如圖：

2、創建 maven項目，pom.xml改成剛剛下載的zip文件中的，新增application.yml文件

pom.xml

<?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>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.6.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.example</groupId>
	<artifactId>sd-provider-user1</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>sd-provider-user1</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>1.8</java.version>
		<spring-cloud.version>Greenwich.SR1</spring-cloud.version>
	</properties>

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

com.example包下新建啓動文件ProviderUserRunApp.java

package com.example;

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

//啓動Eureka客戶端
@EnableEurekaClient
@SpringBootApplication
public class ProviderUserRunApp {
	public static void main(String[] args) {
		SpringApplication.run(ProviderUserRunApp.class, args);
	}
}

resources目錄下新增application.yml文件：

server:
  port: 7900
spring:
  application:
    name: provider-user
eureka:
  client:
    serviceUrl:
      defaultZone: http://user:password123@localhost:8761/eureka
logging:
  level:
    root: INFO

3、添加業務代碼，直接訪問web項目

添加包com.example.controller ，包內添加 HelloController.java類

package com.example.controller;

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

@RestController
public class HelloController {
	@GetMapping("/hello/{name}")
	public String hello(@PathVariable String name) {
		return "1:"+name;
	}
}

4、啓動服務，查看效果，網頁輸入：http://localhost:8761/

3）我們以同樣的方式去創建服務提供者2（provider-user2）

注意，只需要將提供者1中的application.yml文件中端口號修改即可拿來複用，如改爲8010

啓動provider-user2，再次刷新網址：http://localhost:8761/

4）最後，讓我們創建服務消費者

1、start.spring.io中創建模板，仍然選擇 EurekaClient 和web兩個依賴（與provider-user一樣，不再贅述）

2、創建Customer-Client

修改pom.xml

<?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>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.6.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.example</groupId>
	<artifactId>sd-provider-user1</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>sd-provider-user1</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>1.8</java.version>
		<spring-cloud.version>Greenwich.SR1</spring-cloud.version>
	</properties>

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

添加application.yml

server:
  port: 8050
spring:
  application:
    name: consumer-client
eureka:
  client:
    serviceUrl:
      defaultZone: http://user:password123@localhost:8761/eureka
logging:
  level:
    root: INFO

3、添加啓動文件（注意與前面不一樣了）

package com.example;

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 ConsumerRunApp {
        //創建對象
	@Bean
        @LoadBalanced   //實現負載均衡，不加該註解無法實現通過服務提供者名稱訪問
	public RestTemplate restTemplate(){
		return new RestTemplate();
	}
	
	public static void main(String[] args) {
		SpringApplication.run(ConsumerRunApp.class, args);
	}
}

4、添加業務代碼（注意與前面不一樣了）

package com.example.controller;

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

@RestController
public class HelloController {
	@Autowired
	private RestTemplate restTemplate;
	
	@GetMapping("/hello/{name}")
	@ResponseBody
	public String hello(@PathVariable String name){
		String url = "http://provider-user/hello/"+name;   
		return this.restTemplate.getForObject(url, String.class);
	}
}

5、啓動

最後，我們演示下效果，在瀏覽器中輸入：

http://localhost:8050/hello/tony

反覆刷新頁面時，瀏覽器中交替顯示： 1tony 2tony 1tony 2tony 1tony 2tony

可見加了@LoadBalanced註解後，實現了在兩個服務提供者之間的負載均衡。

代碼下載請見個人github:https://github.com/fuhongyu/SpringBoot-demo

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