Environment环境加载

Environment就是指Spring应用运行的环境信息，例如从系统变量、命令行、配置文件application.yml等文件中的信息加载之后都会保存到Environment中。

Environment的初始化

org.springframework.boot.SpringApplication#run(java.lang.String...)

ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);

准备环境的过程中，主要就是创建和配置Spring容器的环境信息：

private ConfigurableEnvironment prepareEnvironment(SpringApplicationRunListeners listeners,ApplicationArguments applicationArguments) {// Create and configure the environment//按照应用的类型创建标准的环境ConfigurableEnvironment environment = getOrCreateEnvironment();//配置环境的PropertySource，设置profilesconfigureEnvironment(environment, applicationArguments.getSourceArgs());ConfigurationPropertySources.attach(environment);//事件驱动加载环境配置listeners.environmentPrepared(environment);bindToSpringApplication(environment);if (!this.isCustomEnvironment) {environment = new EnvironmentConverter(getClassLoader()).convertEnvironmentIfNecessary(environment,deduceEnvironmentClass());}ConfigurationPropertySources.attach(environment);return environment;
}

1. 创建一个标准的环境

private ConfigurableEnvironment getOrCreateEnvironment() {if (this.environment != null) {return this.environment;}switch (this.webApplicationType) {case SERVLET://若是Servlet应用则创建Servlet环境return new StandardServletEnvironment();case REACTIVE://若是reactive应用则创建Servlet环境return new StandardReactiveWebEnvironment();default://否则创建标准环境return new StandardEnvironment();}
}

获取webApplicationType: org.springframework.boot.WebApplicationType#deduceFromClasspath

static WebApplicationType deduceFromClasspath() {//org.springframework.web.reactive.DispatcherHandler类存在，//且org.springframework.web.servlet.DispatcherServlet类不存在//且org.glassfish.jersey.servlet.ServletContainer类不存在,则为REACTIVE应用if (ClassUtils.isPresent(WEBFLUX_INDICATOR_CLASS, null) && !ClassUtils.isPresent(WEBMVC_INDICATOR_CLASS, null)&& !ClassUtils.isPresent(JERSEY_INDICATOR_CLASS, null)) {return WebApplicationType.REACTIVE;}//javax.servlet.Servlet类    //或org.springframework.web.context.ConfigurableWebApplicationContext类不存在则为普通的应用for (String className : SERVLET_INDICATOR_CLASSES) {if (!ClassUtils.isPresent(className, null)) {return WebApplicationType.NONE;}}//否则为Servlet应用return WebApplicationType.SERVLET;}

这里以Servlet应用为例，看下环境的类结构图：

StandardServletEnvironment初始化

由于AbstractEnvironment类初始化调用了customizePropertySource方法，而customizePropertySource在StandardServletEnvironment和StandardEnvironment都有重写，所以会优先执行他们的方法：

org.springframework.web.context.support.StandardServletEnvironment#customizePropertySources

protected void customizePropertySources(MutablePropertySources propertySources) {//将Servlet的配置封装成一个标准的属性源添加到动态可变的属性源列表中propertySources.addLast(new StubPropertySource(SERVLET_CONFIG_PROPERTY_SOURCE_NAME));//将Servlet的上下文封装成一个标准的属性源添加到动态可变的属性源列表中propertySources.addLast(new StubPropertySource(SERVLET_CONTEXT_PROPERTY_SOURCE_NAME));//添加JNDI的属性源if (JndiLocatorDelegate.isDefaultJndiEnvironmentAvailable()) {propertySources.addLast(new JndiPropertySource(JNDI_PROPERTY_SOURCE_NAME));}super.customizePropertySources(propertySources);
}

org.springframework.core.env.StandardEnvironment#customizePropertySources

protected void customizePropertySources(MutablePropertySources propertySources) {////将系统属性源System.getProperties()添加到动态可变的属性源列表中propertySources.addLast(new PropertiesPropertySource(SYSTEM_PROPERTIES_PROPERTY_SOURCE_NAME, getSystemProperties()));//将系统环境属性System.getenv()添加到动态可变的属性源列表中propertySources.addLast(new SystemEnvironmentPropertySource(SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME, getSystemEnvironment()));}

2.配置Environment和配置profiles

org.springframework.boot.SpringApplication#configureEnvironment

protected void configureEnvironment(ConfigurableEnvironment environment, String[] args) {//添加类型转化的服务	if (this.addConversionService) {ConversionService conversionService = ApplicationConversionService.getSharedInstance();environment.setConversionService((ConfigurableConversionService) conversionService);}//配置Environment中的propertysourcesconfigurePropertySources(environment, args);//配置profilesconfigureProfiles(environment, args);}

org.springframework.boot.SpringApplication#configurePropertySources

protected void configurePropertySources(ConfigurableEnvironment environment, String[] args) {MutablePropertySources sources = environment.getPropertySources();//若默认配置不为空，则将默认配置添加到MutablePropertySources，这个defaultProperties可以在SpringApplication中设置if (this.defaultProperties != null && !this.defaultProperties.isEmpty()) {sources.addLast(new MapPropertySource("defaultProperties", this.defaultProperties));}//若设置了命令行属性，则设置成SimpleCommandLinePropertySource添加到MutablePropertySources的最前面if (this.addCommandLineProperties && args.length > 0) {String name = CommandLinePropertySource.COMMAND_LINE_PROPERTY_SOURCE_NAME;if (sources.contains(name)) {PropertySource<?> source = sources.get(name);CompositePropertySource composite = new CompositePropertySource(name);composite.addPropertySource(new SimpleCommandLinePropertySource("springApplicationCommandLineArgs", args));composite.addPropertySource(source);sources.replace(name, composite);}else {sources.addFirst(new SimpleCommandLinePropertySource(args));}}}

org.springframework.boot.SpringApplication#configureProfiles

protected void configureProfiles(ConfigurableEnvironment environment, String[] args) {//若设置了activeProfiles则加入到环境中Set<String> profiles = new LinkedHashSet<>(this.additionalProfiles);profiles.addAll(Arrays.asList(environment.getActiveProfiles()));environment.setActiveProfiles(StringUtils.toStringArray(profiles));}

3.发送环境准备的事件

listeners.environmentPrepared(environment)

void environmentPrepared(ConfigurableEnvironment environment) {for (SpringApplicationRunListener listener : this.listeners) {listener.environmentPrepared(environment);}}

当所有实现了SpringApplicationRunListener的监听器，都会执行environmentPrepared的方法，在spring.factories配置了EventPublishingRunListener类：

org.springframework.boot.SpringApplicationRunListener=\
org.springframework.boot.context.event.EventPublishingRunListener

org.springframework.boot.context.event.EventPublishingRunListener#environmentPrepared

发送了一个ApplicationEnvironmentPreparedEvent事件

public void environmentPrepared(ConfigurableEnvironment environment) {this.initialMulticaster.multicastEvent(new ApplicationEnvironmentPreparedEvent(this.application, this.args, environment));}

而ConfigFileApplicationListener这个监听器正是来监听并处理ApplicationEnvironmentPreparedEvent事件的。

org.springframework.boot.context.config.ConfigFileApplicationListener#onApplicationEvent

public void onApplicationEvent(ApplicationEvent event) {if (event instanceof ApplicationEnvironmentPreparedEvent) {onApplicationEnvironmentPreparedEvent((ApplicationEnvironmentPreparedEvent) event);}if (event instanceof ApplicationPreparedEvent) {onApplicationPreparedEvent(event);}}

接着处理环境准备就绪的事件，配置加载过程

org.springframework.boot.context.config.ConfigFileApplicationListener#onApplicationEnvironmentPreparedEvent

private void onApplicationEnvironmentPreparedEvent(ApplicationEnvironmentPreparedEvent event) {List<EnvironmentPostProcessor> postProcessors = loadPostProcessors();postProcessors.add(this);AnnotationAwareOrderComparator.sort(postProcessors);for (EnvironmentPostProcessor postProcessor : postProcessors) {postProcessor.postProcessEnvironment(event.getEnvironment(), event.getSpringApplication());}}

ConfigFileApplicationListener同样实现了EnvironmentPostProcessor接口，所以最后达到postProcessEnvironment的方法

public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) {addPropertySources(environment, application.getResourceLoader());
}protected void addPropertySources(ConfigurableEnvironment environment, ResourceLoader resourceLoader) {//添加一个RandomValuePropertySource到Environment的MutablePropertySources中RandomValuePropertySource.addToEnvironment(environment);//加载spring boot中的配置信息，比如application.yml或者application.propertiesnew Loader(environment, resourceLoader).load();
}

new Loader(environment, resourceLoader).load()

这里是调用了FilteredPropertySource的apply方法，判断是否有设置defaultProperties，如果有则将默认配置设置一个FilteredPropertySource,然后再调用最后一个参数定义的匿名类(lambda表达式)

void load() {FilteredPropertySource.apply(this.environment, DEFAULT_PROPERTIES, LOAD_FILTERED_PROPERTY,(defaultProperties) -> {this.profiles = new LinkedList<>();this.processedProfiles = new LinkedList<>();this.activatedProfiles = false;this.loaded = new LinkedHashMap<>();initializeProfiles();while (!this.profiles.isEmpty()) {Profile profile = this.profiles.poll();if (isDefaultProfile(profile)) {addProfileToEnvironment(profile.getName());}load(profile, this::getPositiveProfileFilter,addToLoaded(MutablePropertySources::addLast, false));this.processedProfiles.add(profile);}load(null, this::getNegativeProfileFilter, addToLoaded(MutablePropertySources::addFirst, true));addLoadedPropertySources();applyActiveProfiles(defaultProperties);});
}

匿名类主要逻辑：

调用initializeProfiles初始化默认的Profile，没有设置的话就用默认，初始化之后保存到 private Deque<Profile> profiles; 中，它是一个LIFO队列。 因为 profiles 采用了 LIFO 队列，后进先出。所以会先加载profile为null的配置文件 ，也就是匹配 application.properties、application.yml 。
如果profiles不为空，则循环遍历每一个profiles，调用 load方法进行加载。

org.springframework.boot.context.config.ConfigFileApplicationListener.Loader#initializeProfiles

该方法的作用是加载存在已经激活的 profiles，有自己设置的则加载自己设置的profiles，没有的话则使用默认的profiles

private void initializeProfiles() {// The default profile for these purposes is represented as null. We add it// first so that it is processed first and has lowest priority.this.profiles.add(null);Binder binder = Binder.get(this.environment);//获取spring.profiles.active的ProfilesSet<Profile> activatedViaProperty = getProfiles(binder, ACTIVE_PROFILES_PROPERTY);//获取spring.profiles.incloud的ProfilesSet<Profile> includedViaProperty = getProfiles(binder, INCLUDE_PROFILES_PROPERTY);//获取其他的ProfilesList<Profile> otherActiveProfiles = getOtherActiveProfiles(activatedViaProperty, includedViaProperty);this.profiles.addAll(otherActiveProfiles);// Any pre-existing active profiles set via property sources (e.g.// System properties) take precedence over those added in config files.this.profiles.addAll(includedViaProperty);addActiveProfiles(activatedViaProperty);if (this.profiles.size() == 1) { // only has null profile//如果没有设置司机的profiles，则使用默认的profilesfor (String defaultProfileName : this.environment.getDefaultProfiles()) {Profile defaultProfile = new Profile(defaultProfileName, true);this.profiles.add(defaultProfile);}}}

接下来就是具体加载每个Profile

org.springframework.boot.context.config.ConfigFileApplicationListener.Loader#load

搜索约定配置文件的位置，循环每个位置，获取每个位置下的文件名称再进行加载

private void load(Profile profile, DocumentFilterFactory filterFactory, DocumentConsumer consumer) {getSearchLocations().forEach((location) -> {boolean isDirectory = location.endsWith("/");Set<String> names = isDirectory ? getSearchNames() : NO_SEARCH_NAMES;//按照每个名称进行加载names.forEach((name) -> load(location, name, profile, filterFactory, consumer));});}

org.springframework.boot.context.config.ConfigFileApplicationListener.Loader#load(java.lang.String, java.lang.String, org.springframework.boot.context.config.ConfigFileApplicationListener.Profile, org.springframework.boot.context.config.ConfigFileApplicationListener.DocumentFilterFactory, org.springframework.boot.context.config.ConfigFileApplicationListener.DocumentConsumer)

按照文件名称的后缀，获取具体的资源加载器，进行具体文件的加载过程

private void load(String location, String name, Profile profile, DocumentFilterFactory filterFactory,DocumentConsumer consumer) {if (!StringUtils.hasText(name)) {for (PropertySourceLoader loader : this.propertySourceLoaders) {if (canLoadFileExtension(loader, location)) {load(loader, location, profile, filterFactory.getDocumentFilter(profile), consumer);return;}}throw new IllegalStateException("File extension of config file location '" + location+ "' is not known to any PropertySourceLoader. If the location is meant to reference "+ "a directory, it must end in '/'");}Set<String> processed = new HashSet<>();for (PropertySourceLoader loader : this.propertySourceLoaders) {for (String fileExtension : loader.getFileExtensions()) {if (processed.add(fileExtension)) {loadForFileExtension(loader, location + name, "." + fileExtension, profile, filterFactory,consumer);}}}}

资源加载器目前自带的有两种，一种是properties文件加载器，一种是yaml/yml文件加载器：

# PropertySource Loaders
org.springframework.boot.env.PropertySourceLoader=\
org.springframework.boot.env.PropertiesPropertySourceLoader,\
org.springframework.boot.env.YamlPropertySourceLoader

至此，springBoot中的资源文件加载完毕，解析顺序从上到下。

Config Server获取配置

Spring Cloud Config Server提供了EnvironmentController，这样通过在浏览器访问即可从git中获取配置信息

EnvironmentController

@RequestMapping(path = "/{name}/{profiles:.*[^-].*}",produces = MediaType.APPLICATION_JSON_VALUE)public Environment defaultLabel(@PathVariable String name,@PathVariable String profiles) {return getEnvironment(name, profiles, null, false);}@RequestMapping(path = "/{name}/{profiles:.*[^-].*}",produces = EnvironmentMediaType.V2_JSON)public Environment defaultLabelIncludeOrigin(@PathVariable String name,@PathVariable String profiles) {return getEnvironment(name, profiles, null, true);}@RequestMapping(path = "/{name}/{profiles}/{label:.*}",produces = MediaType.APPLICATION_JSON_VALUE)public Environment labelled(@PathVariable String name, @PathVariable String profiles,@PathVariable String label) {return getEnvironment(name, profiles, label, false);}@RequestMapping(path = "/{name}/{profiles}/{label:.*}",produces = EnvironmentMediaType.V2_JSON)public Environment labelledIncludeOrigin(@PathVariable String name,@PathVariable String profiles, @PathVariable String label) {return getEnvironment(name, profiles, label, true);}

我们可以按照application、profiles、label三要素的配置方式来获取远程地址的配置信息，调用的都是getEnvironment方法：

public Environment getEnvironment(String name, String profiles, String label,boolean includeOrigin) {name = normalize(name);label = normalize(label);Environment environment = this.repository.findOne(name, profiles, label,includeOrigin);if (!this.acceptEmpty&& (environment == null || environment.getPropertySources().isEmpty())) {throw new EnvironmentNotFoundException("Profile Not found");}return environment;}

org.springframework.cloud.config.server.environment.MultipleJGitEnvironmentRepository#findOne

以git远程地址为例，调用findOne获取Environment，其实git地址可以配置多个地址，从每个地址中拿到符合application、profiles、label三要素的配置信息

public Environment findOne(String application, String profile, String label,boolean includeOrigin) {for (PatternMatchingJGitEnvironmentRepository repository : this.repos.values()) {if (repository.matches(application, profile, label)) {for (JGitEnvironmentRepository candidate : getRepositories(repository,application, profile, label)) {try {if (label == null) {label = candidate.getDefaultLabel();}Environment source = candidate.findOne(application, profile,label, includeOrigin);if (source != null) {return source;}}catch (Exception e) {if (this.logger.isDebugEnabled()) {this.logger.debug("Cannot load configuration from " + candidate.getUri()+ ", cause: (" + e.getClass().getSimpleName()+ ") " + e.getMessage(),e);}continue;}}}}JGitEnvironmentRepository candidate = getRepository(this, application, profile,label);if (label == null) {label = candidate.getDefaultLabel();}if (candidate == this) {return super.findOne(application, profile, label, includeOrigin);}return candidate.findOne(application, profile, label, includeOrigin);}

org.springframework.cloud.config.server.environment.AbstractScmEnvironmentRepository#findOne(java.lang.String, java.lang.String, java.lang.String, boolean)

调用抽象类的findOne方法，主要有两个核心逻辑
调用getLocations从GIT远程仓库同步到本地
使用 NativeEnvironmentRepository 委托来读取本地文件内容

public synchronized Environment findOne(String application, String profile,String label, boolean includeOrigin) {NativeEnvironmentRepository delegate = new NativeEnvironmentRepository(getEnvironment(), new NativeEnvironmentProperties());Locations locations = getLocations(application, profile, label);delegate.setSearchLocations(locations.getLocations());Environment result = delegate.findOne(application, profile, "", includeOrigin);result.setVersion(locations.getVersion());result.setLabel(label);return this.cleaner.clean(result, getWorkingDirectory().toURI().toString(),getUri());}

至此，服务端获取远程git地址的配置信息完成。

ConfigClient获取配置

在spring boot项目启动时，有一个prepareContext的方法，它会回调所有实现了ApplicationContextInitializer 的实例，来做一些初始化工作。

org.springframework.boot.SpringApplication#prepareContext

private void prepareContext(ConfigurableApplicationContext context, ConfigurableEnvironment environment,SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments, Banner printedBanner) {context.setEnvironment(environment);postProcessApplicationContext(context);applyInitializers(context);listeners.contextPrepared(context);if (this.logStartupInfo) {logStartupInfo(context.getParent() == null);logStartupProfileInfo(context);}// Add boot specific singleton beansConfigurableListableBeanFactory beanFactory = context.getBeanFactory();beanFactory.registerSingleton("springApplicationArguments", applicationArguments);if (printedBanner != null) {beanFactory.registerSingleton("springBootBanner", printedBanner);}if (beanFactory instanceof DefaultListableBeanFactory) {((DefaultListableBeanFactory) beanFactory).setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding);}if (this.lazyInitialization) {context.addBeanFactoryPostProcessor(new LazyInitializationBeanFactoryPostProcessor());}// Load the sourcesSet<Object> sources = getAllSources();Assert.notEmpty(sources, "Sources must not be empty");load(context, sources.toArray(new Object[0]));listeners.contextLoaded(context);}

org.springframework.cloud.bootstrap.config.PropertySourceBootstrapConfiguration#initialize

获取所有PropertySourceLocator, 遍历每个PropertySourceLocator，调用locateCollection获取属性源列表加入到Spring的MutablePropertySources 中

public void initialize(ConfigurableApplicationContext applicationContext) {List<PropertySource<?>> composite = new ArrayList<>();AnnotationAwareOrderComparator.sort(this.propertySourceLocators);boolean empty = true;ConfigurableEnvironment environment = applicationContext.getEnvironment();//遍历每个PropertySourceLocator for (PropertySourceLocator locator : this.propertySourceLocators) {Collection<PropertySource<?>> source = locator.locateCollection(environment);if (source == null || source.size() == 0) {continue;}List<PropertySource<?>> sourceList = new ArrayList<>();for (PropertySource<?> p : source) {//加入到sourceList中if (p instanceof EnumerablePropertySource) {EnumerablePropertySource<?> enumerable = (EnumerablePropertySource<?>) p;sourceList.add(new BootstrapPropertySource<>(enumerable));}else {sourceList.add(new SimpleBootstrapPropertySource(p));}}logger.info("Located property source: " + sourceList);composite.addAll(sourceList);empty = false;}//若获取的属性源不为空的情况下，加入到MutablePropertySources中if (!empty) {MutablePropertySources propertySources = environment.getPropertySources();String logConfig = environment.resolvePlaceholders("${logging.config:}");LogFile logFile = LogFile.get(environment);for (PropertySource<?> p : environment.getPropertySources()) {if (p.getName().startsWith(BOOTSTRAP_PROPERTY_SOURCE_NAME)) {propertySources.remove(p.getName());}}insertPropertySources(propertySources, composite);reinitializeLoggingSystem(environment, logConfig, logFile);setLogLevels(applicationContext, environment);handleIncludedProfiles(environment);}}

org.springframework.cloud.bootstrap.config.PropertySourceLocator#locateCollection(org.springframework.core.env.Environment)

PropertySource<?> locate(Environment environment);default Collection<PropertySource<?>> locateCollection(Environment environment) {return locateCollection(this, environment);}static Collection<PropertySource<?>> locateCollection(PropertySourceLocator locator,Environment environment) {PropertySource<?> propertySource = locator.locate(environment);if (propertySource == null) {return Collections.emptyList();}if (CompositePropertySource.class.isInstance(propertySource)) {Collection<PropertySource<?>> sources = ((CompositePropertySource) propertySource).getPropertySources();List<PropertySource<?>> filteredSources = new ArrayList<>();for (PropertySource<?> p : sources) {if (p != null) {filteredSources.add(p);}}return filteredSources;}else {return Arrays.asList(propertySource);}}

locateCollection获取属性源时,调用了locate方法，而locate方法是抽象方法，由其子类实现，Config Client提供了一个ConfigServicePropertySourceLocator：

org.springframework.cloud.config.client.ConfigServicePropertySourceLocator#locate

通过RestTemplate调用一个Config Server服务获得远程配置信息，然后将信息包装成OriginTrackedMapPropertySource，保存到 CompositePropertySource 中

@Retryable(interceptor = "configServerRetryInterceptor")public org.springframework.core.env.PropertySource<?> locate(org.springframework.core.env.Environment environment) {ConfigClientProperties properties = this.defaultProperties.override(environment);CompositePropertySource composite = new OriginTrackedCompositePropertySource("configService");RestTemplate restTemplate = this.restTemplate == null? getSecureRestTemplate(properties) : this.restTemplate;Exception error = null;String errorBody = null;try {String[] labels = new String[] { "" };if (StringUtils.hasText(properties.getLabel())) {labels = StringUtils.commaDelimitedListToStringArray(properties.getLabel());}String state = ConfigClientStateHolder.getState();// Try all the labels until one worksfor (String label : labels) {Environment result = getRemoteEnvironment(restTemplate, properties,label.trim(), state);if (result != null) {log(result);// result.getPropertySources() can be null if using xmlif (result.getPropertySources() != null) {for (PropertySource source : result.getPropertySources()) {@SuppressWarnings("unchecked")Map<String, Object> map = translateOrigins(source.getName(),(Map<String, Object>) source.getSource());composite.addPropertySource(new OriginTrackedMapPropertySource(source.getName(),map));}}if (StringUtils.hasText(result.getState())|| StringUtils.hasText(result.getVersion())) {HashMap<String, Object> map = new HashMap<>();putValue(map, "config.client.state", result.getState());putValue(map, "config.client.version", result.getVersion());composite.addFirstPropertySource(new MapPropertySource("configClient", map));}return composite;}}errorBody = String.format("None of labels %s found", Arrays.toString(labels));}catch (HttpServerErrorException e) {error = e;if (MediaType.APPLICATION_JSON.includes(e.getResponseHeaders().getContentType())) {errorBody = e.getResponseBodyAsString();}}catch (Exception e) {error = e;}if (properties.isFailFast()) {throw new IllegalStateException("Could not locate PropertySource and the fail fast property is set, failing"+ (errorBody == null ? "" : ": " + errorBody),error);}logger.warn("Could not locate PropertySource: "+ (error != null ? error.getMessage() : errorBody));return null;}