SpringCloud学习笔记(二)-Config配置

Config分为三个部分：ConfigServer ConfigClient 配置仓库

一、ConfigServer如何提供配置

SpringCloud中申明ConfigServer时，通过@EnableConfigServer开启ConfigServer配置。

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(ConfigServerConfiguration.class)
public @interface EnableConfigServer {

}

而EnableConfigServer中又引入了ConfigServerConfiguration，申明了内部类Maker，并装配为一个Bean。

@Configuration
public class ConfigServerConfiguration {
    class Marker {}

    @Bean
    public Marker enableConfigServerMarker() {
        return new Marker();
    }
}

通过ConfigServerConfiguration.Maker又开启了ConfigServerAutoConfiguration配置(通过@ConditionalOnBean(ConfigServerConfiguration.Marker.class)开启，在装配Maker时会执行该配置)。

@Configuration
@ConditionalOnBean(ConfigServerConfiguration.Marker.class)
@EnableConfigurationProperties(ConfigServerProperties.class)
@Import({ EnvironmentRepositoryConfiguration.class, CompositeConfiguration.class, ResourceRepositoryConfiguration.class,
        ConfigServerEncryptionConfiguration.class, ConfigServerMvcConfiguration.class, TransportConfiguration.class })
public class ConfigServerAutoConfiguration {

}

通过@Import引入了6个重要的配置类
EnvironmentRepositoryConfiguration：环境仓库配置，是关键的配置类
CompositeConfiguration：混合配置，用于多环境下配置资源的加载
ResourceRepositoryConfiguration：资源仓库相关配置
ConfigServerEncryptionConfiguration：ConfigServer加密相关配置
ConfigServerMvcConfiguration：对外暴露的MVC相关配置
TransportConfiguration：运行transport命令前，配置回调

EnvironmentRepositoryConfiguration的配置

环境仓库的配置又细分为JDBC、Vault、svn、Native(本地)、Git等配置，默认是Git配置.
多种配置方式，最终都会被装配成EnvironmentRepository，以本地配置装配为例看下类图结构：

EnvironmentRepository

1. NativeEnvironmentRepository本地配置加载

2. GitRepositoryConfiguration Git配置加载

等等...

二、ConfigClient的调用

ConfigServer在启动的时候会申明一个REST接口(EnvironmentController)当有配置客户端查询请求时，通过调用EnvironmentRepository.findOne方法返回一个Environment对象，客户端反序列化得到Environment对象。

@RequestMapping("/{name}/{profiles:.*[^-].*}")
    public Environment defaultLabel(@PathVariable String name,
            @PathVariable String profiles) {
        return labelled(name, profiles, null);
}
@RequestMapping("/{name}/{profiles}/{label:.*}")
    public Environment labelled(@PathVariable String name, @PathVariable String profiles,
            @PathVariable String label) {
        if (label != null && label.contains("(_)")) {
            // "(_)" is uncommon in a git branch name, but "/" cannot be matched
            // by Spring MVC
            label = label.replace("(_)", "/");
        }
        Environment environment = this.repository.findOne(name, profiles, label);
        return environment;
}

findOne根据配置信息解析过滤配置属性，封装为Environment对象返回给客户端。

public class NativeEnvironmentRepository{
//在ConfigClient启动时调用
//config：文件名称，即在Configclient中配置的config.name
//profile：ConfigClient中配置的config.profile
@Override
public Environment findOne(String config, String profile, String label) {
        //启动一个SpringBoot内部微型工程，用于加载配置文件
        SpringApplicationBuilder builder = new SpringApplicationBuilder(
                PropertyPlaceholderAutoConfiguration.class);
        ConfigurableEnvironment environment = getEnvironment(profile);
        builder.environment(environment);
        builder.web(false).bannerMode(Mode.OFF);
        if (!logger.isDebugEnabled()) {
            // Make the mini-application startup less verbose
            builder.logStartupInfo(false);
        }
        String[] args = getArgs(config, profile, label);
        // Explicitly set the listeners (to exclude logging listener which would change
        // log levels in the caller)
        builder.application()
                .setListeners(Arrays.asList(new ConfigFileApplicationListener()));
        ConfigurableApplicationContext context = builder.run(args);
        environment.getPropertySources().remove("profiles");
        try {
            //过滤出所有配置
            return clean(new PassthruEnvironmentRepository(environment).findOne(config,
                    profile, label));
        }
        finally {
            context.close();
        }
    }
}

返回的Environment对象也可以直接通过在地址栏输入http连接看到

Environment