SpringCloud(五)分布式配置中心

当一个系统中的配置文件发生改变的时候，我们需要重新启动该服务，才能使得新的配置文件生效，spring cloud config可以实现微服务中的所有系统的配置文件的统一管理，而且还可以实现当配置文件发生变化的时候，系统会自动更新获取新的配置。在spring cloud config 组件中，分两个角色，一是config server，二是config client。

1.搭建git仓库, https://github.com/JasonSparrow/config.git
2.创建config-client-dev.properties文件, config-client-dev这个文件名称格式是固定的, 服务名称-环境, config-client是服务名称, dev是环境, 客户端会根据这个字段来区分读取哪个配置文件.
3.在config-client-dev.properties文件设置值userName=Jason
4.上传config-client-dev.properties到仓库

分布式配置中心流程图

当client 向 config server 发起请求获取配置信息的时候, config server不会每次都去Git仓库中获取, 而是缓存在内存里, 只有当git仓库配置文件发生变化, 或者客户端需要强制刷新配置中心文件时, config server才会去Git中获取配置信息.

config-server项目搭建

pom文件依赖

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.2.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>
    </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>

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

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Camden.SR6</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>

application.properties 配置文件, 或者application.yml

spring.application.name=config-server
server.port=8889
spring.cloud.config.server.git.uri=https://github.com/JasonSparrow/config.git
spring.cloud.config.server.git.searchPaths=respo
spring.cloud.config.label=master
spring.cloud.config.server.git.username=
spring.cloud.config.server.git.password=

spring.cloud.config.server.git.uri：配置git仓库地址
spring.cloud.config.server.git.searchPaths：配置仓库路径
spring.cloud.config.label：配置仓库的分支
spring.cloud.config.server.git.username：访问git仓库的用户名
spring.cloud.config.server.git.password：访问git仓库的用户密码

启动config-server项目

@SpringBootApplication
@EnableConfigServer
public class ConfigServerApp {
    public static void main(String[] args) {
        SpringApplication.run(ConfigServerApp, args);
    }
}

@EnableConfigServer 开启SpringCloudConfig服务端

config-client项目搭建

pom依赖

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.2.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>
    </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>Dalston.RC1</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>

bootstrap.properties配置文件

#上传到git的文件名config-client-dev.properties
#config-client 名称要一样
spring.application.name=config-client
#分支
spring.cloud.config.label=master
#文件名
spring.cloud.config.profile=dev
#要读取的服务器的地址
spring.cloud.config.uri= http://localhost:8889/
server.port=8881

获取配置中的值

@RestController
public class TestController {

    @Value("${userName}")
    private String userName;

    @RequestMapping("/getUserName")
    public String getUserName() {
        return userName;
    }
}

@Value("${userName}")将会去读取配置中心config-client-dev.properties文件中userName的值

启动config-client

@SpringBootApplication
public class ConfigClientApp {

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

}

注意:先启动config-server, 再启动config-client, 因为config-client启动时需要spring.cloud.config.uri= http://localhost:8889/访问config-server信息.

以上config-server和config-client都是在本地启动的, 但是在微服务架构中, 应该把他们都注册到eureka上, 因为在SpringCloud中, 服务之间是通过项目名称来调用的, 只需要在配置文件中添加如下配置即可.

###服务注册到eureka地址
eureka:
  client:
    service-url:
           defaultZone: http://localhost:8100/eureka