(二)SpringBoot+SpringCloud —— 使用Eureka實現服務註冊與發現

1、建立Eureka註冊中心(Standalone Mode —— 獨立模式)

1.1 建立Eureka Server工程

使用STS建立EurekaServer工程。java

點擊File —— New —— Spring Starter Project後,會彈出建立SpringBoot工程的窗口,輸入工程信息後點擊下一步。git

  • 工程信息能夠選擇構建工具,這裏選擇的Maven;
  • 選擇Packaging,是Jar包仍是War包;
  • 選擇Java版本;
  • 選擇語言(支持Java、Kotlin和Groovy);
  • Group、Artifact、Version和Description爲maven的相關屬性;
  • 最後一個Package是咱們定義的工程主類的包,SpringBoot默認會識別該包和其下的子包;

選擇SpringBoot的版本,並搜索eureka,勾選Eureka Server後,點擊Finish建立工程。github

建立好的工程目錄結構以下:web

工程會自動爲咱們建立maven結構的工程,而且建立了OwlBookstoreEurekaServerApplication類和對應的測試類,在resources文件夾下還有一個空白的application.properties屬性文件。spring

1.2 pom文件

爲了將工程做爲Eureka註冊中心,咱們在建立工程時引入了Eureka Server包,在pom文件中能夠看到:apache

<?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>cn.net.bysoft</groupId>
	<artifactId>owl-bookstore-eureka-server</artifactId>
	<version>1.0-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>owl-bookstore-eureka-server</name>
	<description>owl-bookstore-eureka-server</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.4.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>Dalston.SR1</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>

		<!-- 熱部署 -->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-devtools</artifactId>
			<optional>true</optional>
			<scope>true</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>
			<!-- 熱部署插件 -->
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
				<configuration>
					<fork>true</fork>
				</configuration>
			</plugin>
		</plugins>
	</build>


</project>

1.3 application文件

接下來,咱們修改配置信息,啓動Eureka Server。tomcat

SpringBoot支持yml格式的配置文件,在resources中建立一個application.yml文件,並編寫以下內容:springboot

spring:
  application:
    name: eureka-server
server:
  port: 8761
eureka:
  instance:
    hostname: localhost
  client:
    registerWithEureka: false
    fetchRegistry: false
    serviceUrl:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
debug: true
logging:
  file: wol-bookstore-eureka-server.log
  level:
    root: info
  • spring:application:name:給應用定義一個名稱;
  • server:port:是應用的端口號;
  • eureka:instance:hostname:是應用所在的主機名;
  • eureka:client:registerWithEureka:用於應用是註冊中心,因此不向註冊中心註冊本身;
  • eureka:client:fetchRegistry:用於應用是註冊中心,因此不須要去檢索服務;
  • eureka:client:serviceUrl:defaultZone:定義註冊中心的地址;
  • debug:打開日誌功能;
  • logging:file:日誌文件指向當前應用的目錄;
  • logging:level:root:輸出級別爲info;

1.4 修改主類

最後用@EnableEurekaServer修飾主類OwlBookstoreEurekaServerApplication。bash

package cn.net.bysoft.owl.bootstore;

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

/**
 * <ul>
 * <li>使用<em>@EnableEurekaServer</em>來修飾主類;</li>
 * </ul>
 * 
 * @author xuepeng
 */
@SpringBootApplication
@EnableEurekaServer
public class OwlBookstoreEurekaServerApplication {

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

1.5 運行註冊中心

使用SpringBootApp運行程序,程序運行後訪問地址http://localhost:8761來進入註冊中心。這裏須要注意,雖然配置的是http://${eureka.instance.hostname}:${server.port}/eureka/,可是註冊中心的地址不帶有/eureka。app

到此,Eureka註冊中心已經運行成功了。

2、服務註冊

2.1 建立service-user工程

建立一個服務,命名爲owl-bookstore-service-user。

2.2 pom文件

在pom文件中,加入spring-cloud-starter-eureka依賴。

<?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>cn.net.bysoft</groupId>
	<artifactId>owl-bookstore-service-user</artifactId>
	<version>1.0-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>owl-bookstore-service-user</name>
	<description>owl-bookstore-service-user</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.4.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>Dalston.SR1</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>

2.3 application文件配置

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/
server:
  port: 7001
spring:
  application:
    name: SERVICE-USER
  • eureka:client:serviceUrl:defaultZone:設置註冊中心的地址;
  • server:port:服務的端口號;
  • spring:application:name:服務的名稱,該名稱不要和其餘的服務重名;

2.4 編寫簡單的業務demo

cn.net.bysoft.owl.bookstore.service.user包下存放着主類,使用@EnableDiscoveryClient修飾主類:

package cn.net.bysoft.owl.bookstore.service.user;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public class OwlBookstoreServiceUserApplication {

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

cn.net.bysoft.owl.bookstore.service.user.entity包下存放user服務的實體類:

package cn.net.bysoft.owl.bookstore.service.user.entity;

public class User {

    private final long id;
    private final String name;

    public User(long id, String name) {
        this.id = id;
        this.name = name;
    }

    public long getId() {
        return id;
    }

    public String getName() {
        return name;
    }

}

cn.net.bysoft.owl.bookstore.service.user.facade包下存放着具體的user服務:

package cn.net.bysoft.owl.bookstore.service.user.facade;

import java.util.List;

import cn.net.bysoft.owl.bookstore.service.user.entity.User;

public interface UserService {
    
    List<User> getAll();
    
}

cn.net.bysoft.owl.bookstore.service.user.facade.impl包下存放着服務的實現,用@RestController修飾類,用@RequestMapping修飾方式,@Value用來讀取application.yml文件中的server.port的值:

package cn.net.bysoft.owl.bookstore.service.user.facade.impl;

import java.util.ArrayList;
import java.util.List;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import cn.net.bysoft.owl.bookstore.service.user.entity.User;
import cn.net.bysoft.owl.bookstore.service.user.facade.UserService;

@RestController
public class UserServiceImpl implements UserService {

    @Value("${server.port}")
    String port;

    @RequestMapping(value = "users", method = RequestMethod.GET)
    @Override
    public List<User> getAll() {
        List<User> users = new ArrayList<>();
        users.add(new User(1L, port));
        return users;
    }

}

2.5 啓動服務

啓動服務,並訪問服務地址:http://localhost:7001/users,測試服務是否啓動成功:

經過上圖能夠看到服務已經啓動成功,接下來刷新註冊中心,會發現服務已經註冊到Eureka Server中了:

至此,服務的註冊已經完成。

3、服務發現與使用

3.1 建立消費服務的工程

這裏建立一個bookstore後臺管理的springboot工程,選擇war包方式:

3.2 pom文件

引入如下依賴:

  • spring-cloud-starter-eureka;
  • spring-boot-starter-web;
  • spring-cloud-starter-ribbon;

pom文件的所有內容以下:

<?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>cn.net.bysoft</groupId>
	<artifactId>owl-bookstore-web-console</artifactId>
	<version>1.0-SNAPSHOT</version>
	<packaging>war</packaging>

	<name>owl-bookstore-web-console</name>
	<description>owl-bookstore-service-user</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.4.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>Dalston.SR1</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-web</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-ribbon</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-tomcat</artifactId>
			<scope>provided</scope>
		</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>

3.3 application文件配置

spring:
  application:
    name: owl-bookstore-web-console
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/
server:
  port: 8000

鏈接到數據中心,並將應用端口設置爲8000。

3.4 編寫消費(使用)服務的代碼

cn.net.bysoft.owl.bookstore.web.console包下存放着主類,使用@EnableDiscoveryClient來修飾它,在類中定義了一個RestTemplate,使用它以rest風格來消費(使用)服務,這個類還被@LoadBalanced所修飾,意爲啓動負載均衡。

package cn.net.bysoft.owl.bookstore.web.console;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableDiscoveryClient
public class OwlBookstoreWebConsoleApplication {

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

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

cn.net.bysoft.owl.bookstore.web.console.service包內存放的是業務實現類,自動裝配RestTemplate,並以rest風格,經過http協議,向服務發送get請求。

此處,uri的地址爲服務的[註冊名]/[requestmapping]:

package cn.net.bysoft.owl.bookstore.web.console.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

@Service
public class UserService {

    @Autowired
    RestTemplate restTemplate;

    public String getAll() {
        return restTemplate.getForEntity("http://SERVICE-USER/users", String.class).getBody();
    }

}

cn.net.bysoft.owl.bookstore.web.console.controller包內存放着控制器:

package cn.net.bysoft.owl.bookstore.web.console.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import cn.net.bysoft.owl.bookstore.web.console.service.UserService;

@RestController(value = "/")
public class UserController {

    @Autowired
    UserService userService;

    @RequestMapping(value = "users")
    public String index() {
        return userService.getAll() + " ==> console";
    }

}

3.5 啓動應用消費服務

爲了測試負載均衡,咱們經過命令行的方式啓動兩個service-user:

  • 首先用maven install將service-user打包成jar包;
  • 進入service-user的target文件夾下;
  • 打開cmd,輸入java -jar owl-bookstore-service-user-1.0-SNAPSHOT.jar --server.port=7001;
  • 再打開一個cmd,輸入打開cmd,輸入java -jar owl-bookstore-service-user-1.0-SNAPSHOT.jar --server.port=7002;

如今刷新註冊中心就會發現SERVICE-USER有兩個:

隨後,啓動owl-bookstore-web-console應用,刷新註冊中心,會看到該應用也註冊成功:

如今,訪問http://localhost:8000/users,並刷新頁面,會看到應用經過輪詢的方式消費7001端口與7002端口的服務了。

以上,就是服務註冊與消費的簡單demo。

Github:https://github.com/XuePeng87/owl-bookstore

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