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(二)SpringBoot+SpringCloud —— 使用Eureka实现服务注册与发现

2017-07-05 00:00 1446 查看

一、创建Eureka注册中心(Standalone Mode —— 独立模式)

1.1 创建Eureka Server工程

使用STS创建EurekaServer工程。

点击File —— New —— Spring Starter Project后,会弹出创建SpringBoot工程的窗口,输入工程信息后点击下一步。

工程信息可以选择构建工具,这里选择的Maven;

选择Packaging,是Jar包还是War包;

选择Java版本;

选择语言(支持Java、Kotlin和Groovy);

Group、Artifact、Version和Description为maven的相关属性;

最后一个Package是我们定义的工程主类的包,SpringBoot默认会识别该包和其下的子包;



选择SpringBoot的版本,并搜索eureka,勾选Eureka Server后,点击Finish创建工程。



创建好的工程目录结构如下:



工程会自动为我们创建maven结构的工程,并且创建了OwlBookstoreEurekaServerApplication类和对应的测试类,在resources文件夹下还有一个空白的application.properties属性文件。

1.2 pom文件

为了将工程作为Eureka注册中心,我们在创建工程时引入了Eureka Server包,在pom文件中可以看到:

<?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-
3ff1
starter-test</artifactId>
<scope>test</scope>
</dependency>

<!-- 热部署 -->
<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>
<!-- 热部署插件 -->
<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

接下来,我们修改配置信息,启动Eureka Server。

SpringBoot支持yml格式的配置文件,在resources中创建一个application.yml文件,并编写如下内容:

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:给应用定义一个名称;

server:port:是应用的端口号;

eureka:instance:hostname:是应用所在的主机名;

eureka:client:registerWithEureka:用于应用是注册中心,所以不向注册中心注册自己;

eureka:client:fetchRegistry:用于应用是注册中心,所以不需要去检索服务;

eureka:client:serviceUrl:defaultZone:定义注册中心的地址;

debug:打开日志功能;

logging:file:日志文件指向当前应用的目录;

logging:level:root:输出级别为info;

1.4 修改主类

最后用@EnableEurekaServer修饰主类OwlBookstoreEurekaServerApplication。

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>来修饰主类;</li>
* </ul>
*
* @author xuepeng
*/
@SpringBootApplication
@EnableEurekaServer
public class OwlBookstoreEurekaServerApplication {

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


1.5 运行注册中心

使用SpringBootApp运行程序,程序运行后访问地址http://localhost:8761来进入注册中心。这里需要注意,虽然配置的是http://${eureka.instance.hostname}:${server.port}/eureka/,但是注册中心的地址不带有/eureka。



到此,Eureka注册中心已经运行成功了。

二、服务注册

2.1 创建service-user工程

创建一个服务,命名为owl-bookstore-service-user。



2.2 pom文件

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

<?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:设置注册中心的地址;

server:port:服务的端口号;

spring:application:name:服务的名称,该名称不要和其他的服务重名;

2.4 编写简单的业务demo



cn.net.bysoft.owl.bookstore.service.user包下存放着主类,使用@EnableDiscoveryClient修饰主类:

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服务的实体类:

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包下存放着具体的user服务:

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包下存放着服务的实现,用@RestController修饰类,用@RequestMapping修饰方式,@Value用来读取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 启动服务

启动服务,并访问服务地址:http://localhost:7001/users,测试服务是否启动成功:



通过上图可以看到服务已经启动成功,接下来刷新注册中心,会发现服务已经注册到Eureka Server中了:



至此,服务的注册已经完成。

三、服务发现与使用

3.1 创建消费服务的工程

这里创建一个bookstore后台管理的springboot工程,选择war包方式:



3.2 pom文件

引入以下依赖:

spring-cloud-starter-eureka;

spring-boot-starter-web;

spring-cloud-starter-ribbon;

pom文件的全部内容如下:

<?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>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

连接到数据中心,并将应用端口设置为8000。

3.4 编写消费(使用)服务的代码



cn.net.bysoft.owl.bookstore.web.console包下存放着主类,使用@EnableDiscoveryClient来修饰它,在类中定义了一个RestTemplate,使用它以rest风格来消费(使用)服务,这个类还被@LoadBalanced所修饰,意为启动负载均衡。

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包内存放的是业务实现类,自动装配RestTemplate,并以rest风格,通过http协议,向服务发送get请求。

此处,uri的地址为服务的[注册名]/[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 {

3ff0
@Autowired
RestTemplate restTemplate;

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

}

cn.net.bysoft.owl.bookstore.web.console.controller包内存放着控制器:

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 启动应用消费服务

为了测试负载均衡,我们通过命令行的方式启动两个service-user:

首先用maven install将service-user打包成jar包;

进入service-user的target文件夹下;

打开cmd,输入java -jar owl-bookstore-service-user-1.0-SNAPSHOT.jar --server.port=7001;

再打开一个cmd,输入打开cmd,输入java -jar owl-bookstore-service-user-1.0-SNAPSHOT.jar --server.port=7002;

现在刷新注册中心就会发现SERVICE-USER有两个:



随后,启动owl-bookstore-web-console应用,刷新注册中心,会看到该应用也注册成功:



现在,访问http://localhost:8000/users,并刷新页面,会看到应用通过轮询的方式消费7001端口与7002端口的服务了。





以上,就是服务注册与消费的简单demo。

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