spring boot 源码学习3 - SpringApplication#run environment

SpringApplication#run environment

• • • 解析 environment
    • • prepareEnvironment
      • configureIgnoreBeanInfo

解析 environment

	ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
	// 
    ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
    // 配置spring.beaninfo.ignore
    configureIgnoreBeanInfo(environment);

prepareEnvironment

	private ConfigurableEnvironment prepareEnvironment(SpringApplicationRunListeners listeners,
			ApplicationArguments applicationArguments) {
		// 1、此处返回StandardServletEnvironment
		ConfigurableEnvironment environment = getOrCreateEnvironment();
		// 2、配置环境信息
		configureEnvironment(environment, applicationArguments.getSourceArgs());
		// 3、将source和env关联起来，添加属性：configurationProperties
		ConfigurationPropertySources.attach(environment);
		// 4、发布environmentPrepared事件，添加属性：random、applicationConfig: [classpath:/application.properties]，通过时间监听的方式
		listeners.environmentPrepared(environment);
		// 5、将env绑定到SpringApplication
		bindToSpringApplication(environment);
		if (!this.isCustomEnvironment) {
			environment = new EnvironmentConverter(getClassLoader()).convertEnvironmentIfNecessary(environment,
					deduceEnvironmentClass());
		}
		// 6、将ConfigurationPropertySourc和env关联起来，和步骤3一样
		ConfigurationPropertySources.attach(environment);
		return environment;
	}

（1）getOrCreateEnvironment :

	private ConfigurableEnvironment getOrCreateEnvironment() {
		if (this.environment != null) {
			return this.environment;
		}
		switch (this.webApplicationType) {
		case SERVLET:
			// servlet type
			return new StandardServletEnvironment();
		case REACTIVE:
			return new StandardReactiveWebEnvironment();
		default:
			return new StandardEnvironment();
		}
	}
    
    // new StandardServletEnvironment()会调用此方法
	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);
	}
	
	// StandardEnvironment#customizePropertySources
	protected void customizePropertySources(MutablePropertySources propertySources) {
	 	// 通过 System.getProperties()获取系统属性
		propertySources.addLast(
				new PropertiesPropertySource(SYSTEM_PROPERTIES_PROPERTY_SOURCE_NAME, getSystemProperties()));
		// 通过System.getenv()获取系统变量
		propertySources.addLast(
				new SystemEnvironmentPropertySource(SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME, getSystemEnvironment()));
	}

至此Environment中含有：servletConfigInitParams、servletContextInitParams、systemProperties、systemEnvironment

（2）configureEnvironment：

	protected void configureEnvironment(ConfigurableEnvironment environment, String[] args) {
		if (this.addConversionService) {
			ConversionService conversionService = ApplicationConversionService.getSharedInstance();
			environment.setConversionService((ConfigurableConversionService) conversionService);
		}
		// 配置PropertySources
		configurePropertySources(environment, args);
		// 配置Profiles
		configureProfiles(environment, args);
	}

configurePropertySources：配置属性的source

	protected void configurePropertySources(ConfigurableEnvironment environment, String[] args) {
		MutablePropertySources sources = environment.getPropertySources();
		// 设置defaultProperties
		if (this.defaultProperties != null && !this.defaultProperties.isEmpty()) {
			sources.addLast(new MapPropertySource("defaultProperties", this.defaultProperties));
		}
		// addCommandLineProperties 默认为true，args为0时走此逻辑添加commandLineArgs
		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));
			}
		}
	}

configureProfiles：配置profile想·

	protected void configureProfiles(ConfigurableEnvironment environment, String[] args) {
		Set<String> profiles = new LinkedHashSet<>(this.additionalProfiles);
		profiles.addAll(Arrays.asList(environment.getActiveProfiles()));
		environment.setActiveProfiles(StringUtils.toStringArray(profiles));
	}

	// === 
	public String[] getActiveProfiles() {
		return StringUtils.toStringArray(doGetActiveProfiles());
	}

	// === 
	protected Set<String> doGetActiveProfiles() {
		synchronized (this.activeProfiles) {
			if (this.activeProfiles.isEmpty()) {
				// 
				String profiles = getProperty(ACTIVE_PROFILES_PROPERTY_NAME);
				if (StringUtils.hasText(profiles)) {
					// 将获取到的profile设置到active
					setActiveProfiles(StringUtils.commaDelimitedListToStringArray(
							StringUtils.trimAllWhitespace(profiles)));
				}
			}
			return this.activeProfiles;
		}
	}
	// key = spring.profiles.active
	public String getProperty(String key) {
		return this.propertyResolver.getProperty(key);
	}
	
	// PropertySourcesPropertyResolver#getProperty 获取属性 
	protected <T> T getProperty(String key, Class<T> targetValueType, boolean resolveNestedPlaceholders) {
		if (this.propertySources != null) {
			//还记得这个propertySources吗？
			for (PropertySource<?> propertySource : this.propertySources) {
				if (logger.isTraceEnabled()) {
					logger.trace("Searching for key '" + key + "' in PropertySource '" +
							propertySource.getName() + "'");
				}
				//systemProperties从这个source里，可以获取到spring.profiles.active（前提是在环境变量里设置的）
				Object value = propertySource.getProperty(key);
				if (value != null) {
					if (resolveNestedPlaceholders && value instanceof String) {
						// 取出placeHolder，如${}
						value = resolveNestedPlaceholders((String) value);
					}
					logKeyFound(key, propertySource, value);
					return convertValueIfNecessary(value, targetValueType);
				}
			}
		}
		if (logger.isTraceEnabled()) {
			logger.trace("Could not find key '" + key + "' in any property source");
		}
		return null;
	}

	// 解析placeHolder
	public String resolveRequiredPlaceholders(String text) throws IllegalArgumentException {
		if (this.strictHelper == null) {
			this.strictHelper = createPlaceholderHelper(false);
		}
		return doResolvePlaceholders(text, this.strictHelper);
	}

（3）ConfigurationPropertySources.attach

	public static void attach(Environment environment) {
		Assert.isInstanceOf(ConfigurableEnvironment.class, environment);
		MutablePropertySources sources = ((ConfigurableEnvironment) environment).getPropertySources();
		PropertySource<?> attached = sources.get(ATTACHED_PROPERTY_SOURCE_NAME);
		if (attached != null && attached.getSource() != sources) {
			sources.remove(ATTACHED_PROPERTY_SOURCE_NAME);
			attached = null;
		}
		if (attached == null) {
			// configurationProperties，作用？
			sources.addFirst(new ConfigurationPropertySourcesPropertySource(ATTACHED_PROPERTY_SOURCE_NAME,
					new SpringConfigurationPropertySources(sources)));
		}
	}

configureIgnoreBeanInfo

配置bool值spring.beaninfo.ignore

	private void configureIgnoreBeanInfo(ConfigurableEnvironment environment) {
		if (System.getProperty(CachedIntrospectionResults.IGNORE_BEANINFO_PROPERTY_NAME) == null) {
			Boolean ignore = environment.getProperty("spring.beaninfo.ignore", Boolean.class, Boolean.TRUE);
			System.setProperty(CachedIntrospectionResults.IGNORE_BEANINFO_PROPERTY_NAME, ignore.toString());
		}
	}