springcloud项目配置拓展从本地config目录加载

本文受阿里开源的Nacos启发，应用启动后从Nacos服务加载配置到应用中，想着本地开发的时候加载配置能否从本地存储中加载，这样也能加快开发效率

首先
我们来看下SpringCloud项目应用Nacos服务的bootstrap.yaml配置如下

spring:
  cloud:
    nacos:
      config:
        server-addr: 127.0.0.1:8848
        file-extension: yaml
      discovery:
        server-addr: 127.0.0.1:8848
  application:
    name: demo
  profiles:
    active: db,redis,rabbit,es,zk

然后在Nacos控制台加配置
经过如上之后，这样应用就能从Nacos取配置。

问题点
笔者认为这里开发的时候如果能从文件系统中加载配置替代Nacos，能加快开发效率，也能心情舒畅的Coding业务代码了。

解决思路
分析
经过分析启动配置spring.factories和配置类NacosConfigProperties

org.springframework.cloud.bootstrap.BootstrapConfiguration=\
org.springframework.cloud.alibaba.nacos.NacosConfigBootstrapConfiguration

找到NacosConfigBootstrapConfiguration 代码如下

@Configuration
@ConditionalOnProperty(name = "spring.cloud.nacos.config.enabled", matchIfMissing = true)
public class NacosConfigBootstrapConfiguration {

    @Bean
    @ConditionalOnMissingBean
    public NacosConfigProperties nacosConfigProperties() {
        return new NacosConfigProperties();
    }

    @Bean
    public NacosPropertySourceLocator nacosPropertySourceLocator(
            NacosConfigProperties nacosConfigProperties) {
        return new NacosPropertySourceLocator(nacosConfigProperties);
    }

}

里面关键是NacosPropertySourceLocator实现的接口PropertySourceLocator

/**
 * Strategy for locating (possibly remote) property sources for the Environment.
 * Implementations should not fail unless they intend to prevent the application from
 * starting.
 *
 * @author Dave Syer
 *
 */
public interface PropertySourceLocator {

    /**
     * @param environment The current Environment.
     * @return A PropertySource, or null if there is none.
     * @throws IllegalStateException if there is a fail-fast condition.
     */
    PropertySource<?> locate(Environment environment);

}

到了这里就明白怎么做了。

实现
定义自己的应用启动配置类MyLocalConfigBootstrapConfiguration

@Configuration
@ConditionalOnProperty(name = "spring.cloud.nacos.config.enabled", havingValue = "false")
public class MyLocalConfigBootstrapConfiguration {

    @Bean
    public MyLocalPropertySourceLocator fyLocalPropertySourceLocator() {
        return new MyLocalPropertySourceLocator();
    }
}

定义META-INF/spring.factories

org.springframework.cloud.bootstrap.BootstrapConfiguration=\
com.liyghting.core.MyLocalConfigBootstrapConfiguration

定义自己的配置加载器MyLocalPropertySourceLocator

@Order(0)
public class MyLocalPropertySourceLocator implements PropertySourceLocator {
    private static final Logger LOGGER = LoggerFactory
            .getLogger(MyLocalPropertySourceLocator.class);
    private static final String MYLOCAL_PROPERTY_SOURCE_NAME = "MYLOCAL";

    @Override
    public PropertySource<?> locate(Environment environment) {

        CompositePropertySource composite = new CompositePropertySource(
                MYLOCAL_PROPERTY_SOURCE_NAME);
        String dataIdPrefix = environment.getProperty("spring.application.name");
        String fileExtension = ".yaml";
        PropertySourceLoader propertySourceLoader = new YamlPropertySourceLoader();

        URL baseClassesUrl = this.getClass().getClassLoader().getResource("");
        File baseClassesFile = new File(baseClassesUrl.getFile());
        String basePath = baseClassesFile.getParentFile().getParentFile().getAbsolutePath();

        Resource resource = new FileSystemResource(basePath + "/config/" + dataIdPrefix + fileExtension);
        try {
            composite.addFirstPropertySource(propertySourceLoader.load(dataIdPrefix + fileExtension, resource).get(0));
        } catch (IOException e) {
            LOGGER.warn("can not load property source {}, exception: {}", dataIdPrefix + fileExtension, e);
        }
        for (String activeProfile : environment.getActiveProfiles()) {
            try {
                resource = resource.createRelative(dataIdPrefix + "-" + activeProfile + fileExtension);
                composite.addFirstPropertySource(propertySourceLoader.load(dataIdPrefix + "-" + activeProfile + fileExtension, resource).get(0));
            } catch (IOException e) {
                LOGGER.warn("can not load property source {}, exception: {}", dataIdPrefix + "-" + activeProfile + fileExtension, e);
            }
        }

        return composite;
    }
}

版本信息spring-boot 2.1.6.RELEASE
spring-cloud Greenwich.SR2
spring-cloud-alibaba 0.9.0.RELEASE
具体请看我分享的git库
https://gitee.com/liyghting/SpringCloudLocalCofigDemo

新的bootstarp.yaml配置如下

spring:
  cloud:
    nacos:
      config:
        enabled: false
        server-addr: 127.0.0.1:8848
        file-extension: yaml
      discovery:
        server-addr: 127.0.0.1:8848
  application:
    name: demo
  profiles:
    active: db,redis,rabbit,es,zk

这样应用启动配置能从本地文件系统加载或Nacos服务加载