2.1、簡介

在分布式系統(tǒng)中觉至，由于服務(wù)數(shù)量巨多，為了方便服務(wù)配置文件統(tǒng)一管理睡腿，實時更新语御，所以需要分布式配置中心組件。在Spring Cloud中席怪，有分布式配置中心組件Spring Cloud Config 应闯，它支持配置服務(wù)放在配置服務(wù)的內(nèi)存中，也支持放在遠程Git倉庫中挂捻。在Spring Cloud Config 組件中碉纺，分兩個角色，一是config server细层，二是config client惜辑。

2.2、構(gòu)建Config Server

創(chuàng)建一個叫congfig-server的Spring Boot項目疫赎，引入相關(guān)maven包盛撑。

<?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.voyer</groupId>
    <artifactId>config-server</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

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

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.0.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>Finchley.M9</spring-cloud.version>
    </properties>

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

    <repositories>
        <repository>
            <id>aliyun-maven</id>
            <url>http://maven.aliyun.com/nexus/content/groups/public/</url>
        </repository>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
    </repositories>


</project>

在pom.xml中增加阿里云maven庫，可以提高下載速度捧搞。

        <repository>
            <id>aliyun-maven</id>
            <url>http://maven.aliyun.com/nexus/content/groups/public/</url>
        </repository>

在默認的啟動程序上增加congfigservier注解@EnableConfigServer

@SpringBootApplication
@EnableConfigServer
@RestController
public class ConfigServerApplication {

    @RequestMapping("/")
    public String home() {
        return "Hello World!";
    }
    public static void main(String[] args) {
        SpringApplication.run(ConfigServerApplication.class, args);
    }
}

接下來要在配置文件里配置一下git相關(guān)信息

spring.application.name=config-server
server.port=8888
spring.cloud.config.server.default-application-name=config-server

# 配置git倉庫地址
spring.cloud.config.server.git.uri=https://gitee.com/voyer/config-repo
# 配置倉庫路徑抵卫，多個路徑用逗號分隔
#spring.cloud.config.server.git.search-paths=aliyun
# 配置倉庫的分支
spring.cloud.config.label=master
# 如果Git倉庫為公開倉庫，可以不填寫用戶名和密碼胎撇，如果是私有倉庫需要填寫
# 訪問git倉庫的用戶名
#spring.cloud.config.server.git.username=xxxxoooo
# 訪問git倉庫的用戶密碼 
#spring.cloud.config.server.git.password=xxxxoooo

當然介粘，config也支持配置多個Repositories，也可以通過匹配相關(guān)格式來獲取配置信息晚树，多個匹配格式用逗號分隔姻采，例如：(可以參考官方文檔)。

spring:
  cloud:
    config:
      server:
        git:
          uri: https://github.com/spring-cloud-samples/config-repo
          repos:
            simple: https://github.com/simple/config-repo
            special:
              pattern: special*/dev*,*special*/dev*
              uri: https://github.com/special/config-repo
            local:
              pattern: local*
              uri: file:/home/configsvc/config-repo

遠程倉庫中有幾個文件

啟動程序訪問http://localhost:8080/test/dev返回結(jié)果：

{"name":"test","profiles":["dev"],"label":null,"version":"74cdd22f87198215007e8edf138eb59954b66778","state":null,"propertySources":[]}

證明config server可以從遠程git倉庫獲取配置信息爵憎。

http請求地址和資源文件映射關(guān)系如下：

• /{application}/{profile}[/{label}]
• /{application}-{profile}.yml
• /{label}/{application}-{profile}.yml
• /{application}-{profile}.properties
• /{label}/{application}-{profile}.properties

2.3慨亲、構(gòu)建一個config client

創(chuàng)建一個叫congfig-client的Spring Boot項目，引入相關(guān)maven包宝鼓。

<?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.voyer</groupId>
    <artifactId>config-client</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>config-client</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.0.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>Finchley.M9</spring-cloud.version>
    </properties>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</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>

    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
    </repositories>


</project>

注意此處需要引入spring-boot-starter-web刑棵，否則會無法啟動（但是可以編譯通過），接下來要引入配置文件application.properties

spring.application.name=config-client
#指明遠程倉庫的分支
spring.cloud.config.label=master
#配置文件環(huán)境
spring.cloud.config.profile=dev
# 指明配置服務(wù)中心的網(wǎng)址愚铡。
spring.cloud.config.uri=http://localhost:8888/
server.port=8889
# 總結(jié)一下,config-client項目啟動報錯,獲取不到配置文件里的值:
# 1蛉签、首先確定項目config-client與config-service的spring-boot,spring-cloud的依賴版本要一致
# 2、配置文件命名,要遵循一定規(guī)則,如果項目config-client里命名為config-client,那配置文件就應(yīng)該是config-client-**.properties

在程序啟動入口增加獲取config server配置信息的代碼：

@SpringBootApplication
@RestController
public class ConfigClientApplication {
    @Value("${test}")
    String test;
    @RequestMapping(value = "hi")
    public String hi(){
        return test;
    }
    public static void main(String[] args) {
        SpringApplication.run(ConfigClientApplication.class, args);
    }
}

注意此處的spring.application.name=config-client，當啟動程序時碍舍，會看到控制臺打印的日志：

2018-04-04 16:21:14.904  INFO 32036 --- [           main] c.c.c.ConfigServicePropertySourceLocator : Fetching config from server at: http://localhost:8888
2018-04-04 16:21:15.795  INFO 32036 --- [           main] c.c.c.ConfigServicePropertySourceLocator : Located environment: name=config-client, profiles=[dev], label=master, version=74cdd22f87198215007e8edf138eb59954b66778, state=null
2018-04-04 16:21:15.796  INFO 32036 --- [           main] b.c.PropertySourceBootstrapConfiguration : Located property source: CompositePropertySource {name='configService', propertySources=[MapPropertySource {name='configClient'}, MapPropertySource {name='https://gitee.com/voyer/config-repo/config-client-dev.yml'}, MapPropertySource {name='https://gitee.com/voyer/config-repo/config-client.yml'}]}

可以看到加載了兩個配置文件https://gitee.com/voyer/config-repo/config-client-dev.yml柠座、https://gitee.com/voyer/config-repo/config-client.yml，訪問http://localhost:8889/hi,會看到返回信息：

bbb

唔乒验，此處筆者遠程git倉庫的test值為bbb愚隧，各位讀者可以自己定義。
這就說明锻全，config-client從config-server獲取了test的屬性狂塘，而config-server是從git倉庫讀取的。