Spring Cloud簡(jiǎn)介

Spring Cloud是一個(gè)基于Spring Boot實(shí)現(xiàn)的云應(yīng)用開(kāi)發(fā)工具擒贸，它為基于JVM的云應(yīng)用開(kāi)發(fā)中的配置管理干旁、服務(wù)發(fā)現(xiàn)盖喷、斷路器、智能路由雷绢、微代理臂拓、控制總線、全局鎖习寸、決策競(jìng)選胶惰、分布式會(huì)話和集群狀態(tài)管理等操作提供了一種簡(jiǎn)單的開(kāi)發(fā)方式。

Spring Cloud包含了多個(gè)子項(xiàng)目（針對(duì)分布式系統(tǒng)中涉及的多個(gè)不同開(kāi)源產(chǎn)品）霞溪，比如：Spring Cloud Config孵滞、Spring Cloud Netflix、Spring Cloud CloudFoundry鸯匹、Spring Cloud AWS坊饶、Spring Cloud Security、Spring Cloud Commons殴蓬、Spring Cloud Zookeeper匿级、Spring Cloud CLI等項(xiàng)目。

微服務(wù)架構(gòu)

“微服務(wù)架構(gòu)”在這幾年非常的火熱染厅，以至于關(guān)于微服務(wù)架構(gòu)相關(guān)的產(chǎn)品社區(qū)也變得越來(lái)越活躍（比如：netflix痘绎、dubbo），Spring Cloud也因Spring社區(qū)的強(qiáng)大知名度和影響力也被廣大架構(gòu)師與開(kāi)發(fā)者備受關(guān)注肖粮。
那么什么是“微服務(wù)架構(gòu)”呢孤页？簡(jiǎn)單的說(shuō)，微服務(wù)架構(gòu)就是將一個(gè)完整的應(yīng)用從數(shù)據(jù)存儲(chǔ)開(kāi)始垂直拆分成多個(gè)不同的服務(wù)涩馆，每個(gè)服務(wù)都能獨(dú)立部署行施、獨(dú)立維護(hù)允坚、獨(dú)立擴(kuò)展，服務(wù)與服務(wù)間通過(guò)諸如RESTful API的方式互相調(diào)用蛾号。
對(duì)于“微服務(wù)架構(gòu)”稠项，大家在互聯(lián)網(wǎng)可以搜索到很多相關(guān)的介紹和研究文章來(lái)進(jìn)行學(xué)習(xí)和了解。也可以閱讀始祖Martin Fowler的《Microservices》鲜结，本文不做更多的介紹和描述皿渗。

服務(wù)注冊(cè)與發(fā)現(xiàn)

在簡(jiǎn)單介紹了Spring Cloud和微服務(wù)架構(gòu)之后，下面回歸本文的主旨內(nèi)容轻腺，如何使用Spring Cloud搭建服務(wù)注冊(cè)與發(fā)現(xiàn)模塊。
這里我們會(huì)用到Spring Cloud Netflix划乖，該項(xiàng)目是Spring Cloud的子項(xiàng)目之一贬养，主要內(nèi)容是對(duì)Netflix公司一系列開(kāi)源產(chǎn)品的包裝，它為Spring Boot應(yīng)用提供了自配置的Netflix OSS整合琴庵。通過(guò)一些簡(jiǎn)單的注解误算，開(kāi)發(fā)者就可以快速的在應(yīng)用中配置一下常用模塊并構(gòu)建龐大的分布式系統(tǒng)。它主要提供的模塊包括：服務(wù)發(fā)現(xiàn)（Eureka）迷殿，斷路器（Hystrix）儿礼，智能路有（Zuul），客戶端負(fù)載均衡（Ribbon）等庆寺。
所以蚊夫，我們這里的核心內(nèi)容就是服務(wù)發(fā)現(xiàn)模塊：Eureka。下面我們動(dòng)手來(lái)做一些嘗試懦尝。

1.創(chuàng)建服務(wù)注冊(cè)中心

1） 創(chuàng)建一個(gè)基礎(chǔ)的Spring Boot工程知纷，pom.xml內(nèi)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>com.shijie</groupId>
    <artifactId>springcloudserver</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>springcloudserver</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.6.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.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>

2）在application.yml文件中添加以下內(nèi)容

server:
  port: 8761

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

3）在默認(rèn)的${projectName}Application.java文件中添加@EnableEurekaServer注解

@EnableEurekaServer
@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        new SpringApplicationBuilder(Application.class).web(true).run(args);
    }
}

在瀏覽器輸入localhost:8761

2.創(chuàng)建提供服務(wù)的客戶端

1） 創(chuàng)建一個(gè)基礎(chǔ)的Spring Boot工程，pom.xml內(nèi)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>com.shijie</groupId>
    <artifactId>springcloudclient</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>

    <name>springCloudClient</name>
    <description>client project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.6.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.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>

2）在application.yml文件中添加以下內(nèi)容（指定服務(wù)為service-hi）

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/
server:
  port: 8763
spring:
  application:
    name: service-hi

3）在默認(rèn)的${projectName}Application.java文件中添加以下內(nèi)容的注解

@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient //這里可以打印log
@RestController
public class SpringCloudClientApplication {
    public static void main(String[] args) {
        SpringApplication.run(SpringCloudClientApplication.class, args);
    }
}

4）一個(gè)帶日志的demo之controller
新建ComputerContrller類陵霉，內(nèi)容如下：

package com.shijie.controller;

import org.apache.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;


/**
 * Created by shijie on 2017/8/24 0024.
 */
@RestController
public class ComputerController {

    private final Logger logger  = Logger.getLogger(getClass());

    @Autowired
    private DiscoveryClient client;

    @RequestMapping(value = "/add" ,method = RequestMethod.GET)
    public Integer add(@RequestParam Integer a, @RequestParam Integer b) {
        ServiceInstance instance = client.getLocalServiceInstance();
        Integer r = a + b;
        logger.info("/add, host:" + instance.getHost() + ", service_id:" + instance.getServiceId() + ", result:" + r);
        return r;
    }

}

在瀏覽器輸入localhost:8763,然后訪問(wèn)或刷新之前的localhost:8761可以看到有一個(gè)新的服務(wù)service-hi
訪問(wèn)localhost:8763/add
可以在console控制臺(tái)可以看到日志琅轧，在瀏覽器可以看到打印3

以下是效果圖：

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Paste_Image.png

Paste_Image.png