内容简介:在对入口程序中标记的四步,分析如下加载
在 SpringApplication#run(String... args)
方法中,外部化配置关键流程分为以下四步
public ConfigurableApplicationContext run(String... args) { ... SpringApplicationRunListeners listeners = getRunListeners(args); // 1 listeners.starting(); try { ApplicationArguments applicationArguments = new DefaultApplicationArguments( args); ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments); // 2 configureIgnoreBeanInfo(environment); Banner printedBanner = printBanner(environment); context = createApplicationContext(); exceptionReporters = getSpringFactoriesInstances( SpringBootExceptionReporter.class, new Class[] { ConfigurableApplicationContext.class }, context); prepareContext(context, environment, listeners, applicationArguments, printedBanner); // 3 refreshContext(context); // 4 afterRefresh(context, applicationArguments); stopWatch.stop(); if (this.logStartupInfo) { new StartupInfoLogger(this.mainApplicationClass) .logStarted(getApplicationLog(), stopWatch); } listeners.started(context); callRunners(context, applicationArguments); } ... } 复制代码
关键流程思维导图
关键流程详解
对入口程序中标记的四步,分析如下
1、 SpringApplication#getRunListeners
加载 META-INF/spring.factories
获取 SpringApplicationRunListener
的实例集合,存放的对象是 EventPublishingRunListener
类型 以及自定义的 SpringApplicationRunListener
实现类型
2、 SpringApplication#prepareEnvironment
prepareEnvironment
方法中,主要的三步如下
private ConfigurableEnvironment prepareEnvironment(SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments) { // Create and configure the environment ConfigurableEnvironment environment = getOrCreateEnvironment(); // 2.1 configureEnvironment(environment, applicationArguments.getSourceArgs()); // 2.2 listeners.environmentPrepared(environment); // 2.3 ... return environment; } 复制代码
2.1、 getOrCreateEnvironment
方法
在 WebApplicationType.SERVLET
web应用类型下,会创建 StandardServletEnvironment
,本文以 StandardServletEnvironment
为例,类的层次结构如下
当创建 StandardServletEnvironment
, StandardServletEnvironment
父类 AbstractEnvironment
调用 customizePropertySources
方法,会执行 StandardServletEnvironment#customizePropertySources
和 StandardEnvironment#customizePropertySources
,源码如下
AbstractEnvironment
public AbstractEnvironment() { customizePropertySources(this.propertySources); if (logger.isDebugEnabled()) { logger.debug("Initialized " + getClass().getSimpleName() + " with PropertySources " + this.propertySources); } } 复制代码
StandardServletEnvironment#customizePropertySources
/** Servlet context init parameters property source name: {@value} */ public static final String SERVLET_CONTEXT_PROPERTY_SOURCE_NAME = "servletContextInitParams"; /** Servlet config init parameters property source name: {@value} */ public static final String SERVLET_CONFIG_PROPERTY_SOURCE_NAME = "servletConfigInitParams"; /** JNDI property source name: {@value} */ public static final String JNDI_PROPERTY_SOURCE_NAME = "jndiProperties"; @Override protected void customizePropertySources(MutablePropertySources propertySources) { propertySources.addLast(new StubPropertySource(SERVLET_CONFIG_PROPERTY_SOURCE_NAME)); propertySources.addLast(new StubPropertySource(SERVLET_CONTEXT_PROPERTY_SOURCE_NAME)); if (JndiLocatorDelegate.isDefaultJndiEnvironmentAvailable()) { propertySources.addLast(new JndiPropertySource(JNDI_PROPERTY_SOURCE_NAME)); } super.customizePropertySources(propertySources); } 复制代码
StandardEnvironment#customizePropertySources
/** System environment property source name: {@value} */ public static final String SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME = "systemEnvironment"; /** JVM system properties property source name: {@value} */ public static final String SYSTEM_PROPERTIES_PROPERTY_SOURCE_NAME = "systemProperties"; @Override protected void customizePropertySources(MutablePropertySources propertySources) { propertySources.addLast(new MapPropertySource(SYSTEM_PROPERTIES_PROPERTY_SOURCE_NAME, getSystemProperties())); propertySources.addLast(new SystemEnvironmentPropertySource(SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME,getSystemEnvironment()); } 复制代码
PropertySources
顺序:
- servletConfigInitParams
- servletContextInitParams
- jndiProperties
- systemProperties
- systemEnvironment
PropertySources
与 PropertySource
关系为 1 对 N
2.2、 configureEnvironment
方法
调用 configurePropertySources(environment, args)
, 在方法里面设置 Environment
的 PropertySources
, 包含 defaultProperties
和 SimpleCommandLinePropertySource
(commandLineArgs), PropertySources
添加 defaultProperties
到最后,添加 SimpleCommandLinePropertySource
(commandLineArgs)到最前面
PropertySources
顺序:
-
commandLineArgs
-
servletConfigInitParams
-
servletContextInitParams
-
jndiProperties
-
systemProperties
-
systemEnvironment
-
defaultProperties
2.3、 listeners.environmentPrepared
方法
会按优先级顺序遍历执行 SpringApplicationRunListener#environmentPrepared
,比如 EventPublishingRunListener
和 自定义的 SpringApplicationRunListener
-
EventPublishingRunListener
发布ApplicationEnvironmentPreparedEvent
事件-
ConfigFileApplicationListener
监听ApplicationEvent
事件 、处理ApplicationEnvironmentPreparedEvent
事件,加载所有EnvironmentPostProcessor
包括自己,然后按照顺序进行方法回调-
ConfigFileApplicationListener#postProcessEnvironment
方法回调 ,然后addPropertySources
方法调用RandomValuePropertySource#addToEnvironment
,在 systemEnvironment 后面添加 random,然后添加配置文件的属性源(详见源码ConfigFileApplicationListener.Loader#load()
-
-
-
扩展点
-
自定义
SpringApplicationRunListener
,重写environmentPrepared
方法 -
自定义
EnvironmentPostProcessor
-
自定义
ApplicationListener
监听ApplicationEnvironmentPreparedEvent
事件
-
ConfigFileApplicationListener
,即是 EnvironmentPostProcessor
,又是 ApplicationListener
,类的层次结构如下
@Override public void onApplicationEvent(ApplicationEvent event) { // 处理 ApplicationEnvironmentPreparedEvent 事件 if (event instanceof ApplicationEnvironmentPreparedEvent) { onApplicationEnvironmentPreparedEvent( (ApplicationEnvironmentPreparedEvent) event); } // 处理 ApplicationPreparedEvent 事件 if (event instanceof ApplicationPreparedEvent) { onApplicationPreparedEvent(event); } } private void onApplicationEnvironmentPreparedEvent( ApplicationEnvironmentPreparedEvent event) { // 加载 META-INF/spring.factories 中配置的 EnvironmentPostProcessor List<EnvironmentPostProcessor> postProcessors = loadPostProcessors(); // 加载自己 ConfigFileApplicationListener postProcessors.add(this); // 按照 Ordered 进行优先级排序 AnnotationAwareOrderComparator.sort(postProcessors); // 回调 EnvironmentPostProcessor for (EnvironmentPostProcessor postProcessor : postProcessors) { postProcessor.postProcessEnvironment(event.getEnvironment(), event.getSpringApplication()); } } List<EnvironmentPostProcessor> loadPostProcessors() { return SpringFactoriesLoader.loadFactories(EnvironmentPostProcessor.class, getClass().getClassLoader()); } @Override public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) { addPropertySources(environment, application.getResourceLoader()); } /** * Add config file property sources to the specified environment. * @param environment the environment to add source to * @param resourceLoader the resource loader * @see #addPostProcessors(ConfigurableApplicationContext) */ protected void addPropertySources(ConfigurableEnvironment environment, ResourceLoader resourceLoader) { RandomValuePropertySource.addToEnvironment(environment); // 添加配置文件的属性源 new Loader(environment, resourceLoader).load(); } 复制代码
RandomValuePropertySource
public static void addToEnvironment(ConfigurableEnvironment environment) { // 在 systemEnvironment 后面添加 random environment.getPropertySources().addAfter( StandardEnvironment.SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME, new RandomValuePropertySource(RANDOM_PROPERTY_SOURCE_NAME)); logger.trace("RandomValuePropertySource add to Environment"); } 复制代码
添加配置文件的属性源:
执行 new Loader(environment, resourceLoader).load();
, 调用 load(Profile, DocumentFilterFactory, DocumentConsumer)
(getSearchLocations() 获取配置文件位置,可以指定通过 spring.config.additional-location 、spring.config.location 、spring.config.name 参数或者使用默认值 ), 然后调用 addLoadedPropertySources -> addLoadedPropertySource
(加载 查找出来的 PropertySource
到 PropertySources
,并确保放置到 defaultProperties 的前面 )
默认的查找位置,配置为 "classpath:/,classpath:/config/,file:./,file:./config/"
,查找顺序从后向前
PropertySources
顺序:
- commandLineArgs
- servletConfigInitParams
- servletContextInitParams
- jndiProperties
- systemProperties
- systemEnvironment
- random
- application.properties ...
- defaultProperties
3、 SpringApplication#prepareContext
prepareContext
方法中,主要的三步如下
private void prepareContext(ConfigurableApplicationContext context, ConfigurableEnvironment environment, SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments, Banner printedBanner) { ... applyInitializers(context); // 3.1 listeners.contextPrepared(context); //3.2 ... listeners.contextLoaded(context); // 3.3 } 复制代码
3.1、 applyInitializers
方法
会遍历执行所有的 ApplicationContextInitializer#initialize
- 扩展点
- 自定义
ApplicationContextInitializer
- 自定义
3.2、 listeners.contextPrepared
方法
会按优先级顺序遍历执行 SpringApplicationRunListener#contextPrepared
,比如 EventPublishingRunListener
和 自定义的 SpringApplicationRunListener
- 扩展点
- 自定义
SpringApplicationRunListener
,重写contextPrepared
方法
- 自定义
3.3、 listeners.contextLoaded
方法
会按优先级顺序遍历执行 SpringApplicationRunListener#contextLoaded
,比如 EventPublishingRunListener
和 自定义的 SpringApplicationRunListener
-
EventPublishingRunListener
发布ApplicationPreparedEvent
事件-
ConfigFileApplicationListener
监听ApplicationEvent
事件 处理ApplicationPreparedEvent
事件
-
-
扩展点
- 自定义
SpringApplicationRunListener
,重写contextLoaded
方法 - 自定义
ApplicationListener
,监听ApplicationPreparedEvent
事件
- 自定义
ConfigFileApplicationListener
@Override public void onApplicationEvent(ApplicationEvent event) { // 处理 ApplicationEnvironmentPreparedEvent 事件 if (event instanceof ApplicationEnvironmentPreparedEvent) { onApplicationEnvironmentPreparedEvent( (ApplicationEnvironmentPreparedEvent) event); } // 处理 ApplicationPreparedEvent 事件 if (event instanceof ApplicationPreparedEvent) { onApplicationPreparedEvent(event); } } private void onApplicationPreparedEvent(ApplicationEvent event) { this.logger.replayTo(ConfigFileApplicationListener.class); addPostProcessors(((ApplicationPreparedEvent) event).getApplicationContext()); } // 添加 PropertySourceOrderingPostProcessor 处理器,配置 PropertySources protected void addPostProcessors(ConfigurableApplicationContext context) { context.addBeanFactoryPostProcessor( new PropertySourceOrderingPostProcessor(context)); } 复制代码
PropertySourceOrderingPostProcessor
// 回调处理(在配置类属性源解析) @Override public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { reorderSources(this.context.getEnvironment()); } // 调整 PropertySources 顺序,先删除 defaultProperties, 再把 defaultProperties 添加到最后 private void reorderSources(ConfigurableEnvironment environment) { PropertySource<?> defaultProperties = environment.getPropertySources() .remove(DEFAULT_PROPERTIES); if (defaultProperties != null) { environment.getPropertySources().addLast(defaultProperties); } } 复制代码
PropertySourceOrderingPostProcessor
是 BeanFactoryPostProcessor
4、 SpringApplication#refreshContext
会进行 @Configuration
配置类属性源解析,处理 @PropertySource
annotations on your @Configuration
classes,但顺序是在 defaultProperties 之后,下面会把 defaultProperties 调整到最后
AbstractApplicationContext#refresh
调用 invokeBeanFactoryPostProcessors
( PostProcessorRegistrationDelegate#invokeBeanFactoryPostProcessors
), 然后进行 BeanFactoryPostProcessor
的回调处理 ,比如 PropertySourceOrderingPostProcessor
的回调(源码见上文)
PropertySources
顺序:
-
commandLineArgs
-
servletConfigInitParams
-
servletContextInitParams
-
jndiProperties
-
systemProperties
-
systemEnvironment
-
random
-
application.properties ...
-
@PropertySource
annotations on your@Configuration
classes -
defaultProperties
不推荐使用这种方式,推荐使用在 refreshContext 之前准备好, @PropertySource
加载太晚,不会对自动配置产生任何影响
二、扩展外部化配置属性源
1、基于 EnvironmentPostProcessor
扩展
public class CustomEnvironmentPostProcessor implements EnvironmentPostProcessor 复制代码
2、基于 ApplicationEnvironmentPreparedEvent
扩展
public class ApplicationEnvironmentPreparedEventListener implements ApplicationListener<ApplicationEnvironmentPreparedEvent> 复制代码
3、基于 SpringApplicationRunListener
扩展
public class CustomSpringApplicationRunListener implements SpringApplicationRunListener, Ordered 复制代码
可以重写方法 environmentPrepared、contextPrepared、contextLoaded 进行扩展
4、基于 ApplicationContextInitializer
扩展
public class CustomApplicationContextInitializer implements ApplicationContextInitializer 复制代码
关于与 Spring Cloud Config Client 整合,对外部化配置加载的扩展(绑定到Config Server,使用远端的property sources 初始化 Environment
),参考源码 PropertySourceBootstrapConfiguration
(是对 ApplicationContextInitializer
的扩展)、 ConfigServicePropertySourceLocator#locate
获取远端的property sources是 RestTemplate
通过向 http://{spring.cloud.config.uri}/{ spring.application.name }/{spring.cloud.config.profile}/{spring.cloud.config.label} 发送 GET 请求方式获取的
5、基于 ApplicationPreparedEvent
扩展
public class ApplicationPreparedEventListener implements ApplicationListener<ApplicationPreparedEvent> 复制代码
6、扩展实战
6.1、扩展配置
在 classpath 下添加配置文件 META-INF/spring.factories
, 内容如下
# Spring Application Run Listeners org.springframework.boot.SpringApplicationRunListener=\ springboot.propertysource.extend.listener.CustomSpringApplicationRunListener # Application Context Initializers org.springframework.context.ApplicationContextInitializer=\ springboot.propertysource.extend.initializer.CustomApplicationContextInitializer # Application Listeners org.springframework.context.ApplicationListener=\ springboot.propertysource.extend.event.listener.ApplicationEnvironmentPreparedEventListener,\ springboot.propertysource.extend.event.listener.ApplicationPreparedEventListener # Environment Post Processors org.springframework.boot.env.EnvironmentPostProcessor=\ springboot.propertysource.extend.processor.CustomEnvironmentPostProcessor 复制代码
以上的扩展可以选取其中一种进行扩展,只是属性源的加载时机不太一样
6.2、扩展实例代码
PropertySources
顺序:
propertySourceName: [ApplicationPreparedEventListener], propertySourceClassName: [OriginTrackedMapPropertySource] propertySourceName: [CustomSpringApplicationRunListener-contextLoaded], propertySourceClassName: [OriginTrackedMapPropertySource] propertySourceName: [CustomSpringApplicationRunListener-contextPrepared], propertySourceClassName: [OriginTrackedMapPropertySource] propertySourceName: [CustomApplicationContextInitializer], propertySourceClassName: [OriginTrackedMapPropertySource] propertySourceName: [bootstrapProperties], propertySourceClassName: [CompositePropertySource] propertySourceName: [configurationProperties], propertySourceClassName: [ConfigurationPropertySourcesPropertySource] propertySourceName: [CustomSpringApplicationRunListener-environmentPrepared], propertySourceClassName: [OriginTrackedMapPropertySource] propertySourceName: [CustomEnvironmentPostProcessor-dev-application], propertySourceClassName: [OriginTrackedMapPropertySource] propertySourceName: [ApplicationEnvironmentPreparedEventListener], propertySourceClassName: [OriginTrackedMapPropertySource] propertySourceName: [commandLineArgs], propertySourceClassName: [SimpleCommandLinePropertySource] propertySourceName: [servletConfigInitParams], propertySourceClassName: [StubPropertySource] propertySourceName: [servletContextInitParams], propertySourceClassName: [ServletContextPropertySource] propertySourceName: [systemProperties], propertySourceClassName: [MapPropertySource] propertySourceName: [systemEnvironment], propertySourceClassName: [OriginAwareSystemEnvironmentPropertySource] propertySourceName: [random], propertySourceClassName: [RandomValuePropertySource] propertySourceName: [applicationConfig: [classpath:/extend/config/springApplicationRunListener.properties]], propertySourceClassName: [OriginTrackedMapPropertySource] propertySourceName: [applicationConfig: [classpath:/extend/config/applicationListener.properties]], propertySourceClassName: [OriginTrackedMapPropertySource] propertySourceName: [applicationConfig: [classpath:/extend/config/applicationContextInitializer.properties]], propertySourceClassName: [OriginTrackedMapPropertySource] propertySourceName: [applicationConfig: [classpath:/extend/config/environmentPostProcessor.properties]], propertySourceClassName: [OriginTrackedMapPropertySource] propertySourceName: [applicationConfig: [classpath:/extend/config/application.properties]], propertySourceClassName: [OriginTrackedMapPropertySource] propertySourceName: [applicationConfig: [classpath:/extend/config/config.properties]], propertySourceClassName: [OriginTrackedMapPropertySource] propertySourceName: [applicationConfig: [classpath:/application.properties]], propertySourceClassName: [OriginTrackedMapPropertySource] propertySourceName: [springCloudClientHostInfo], propertySourceClassName: [MapPropertySource] propertySourceName: [applicationConfig: [classpath:/bootstrap.properties]], propertySourceClassName: [OriginTrackedMapPropertySource] propertySourceName: [propertySourceConfig], propertySourceClassName: [ResourcePropertySource] propertySourceName: [defaultProperties], propertySourceClassName: [MapPropertySource] 复制代码
bootstrapProperties 是 获取远端(config-server)的 property sources
加载顺序也可参考 http://{host}:{port}/actuator/env
PropertySources
单元测试顺序:
@TestPropertySource#properties @SpringBootTest#properties @TestPropertySource#locations 复制代码
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