SpringBoot配置的加载流程详细分析

ApplicationArguments applicationArguments = new DefaultApplicationArguments(
					args);
			ConfigurableEnvironment environment = prepareEnvironment(listeners,
					applicationArguments);

public SimpleCommandLinePropertySource(String... args) {
		super(new SimpleCommandLineArgsParser().parse(args));
	}

public CommandLineArgs parse(String... args) {
		//构建个缓存，将解析的参数分别放入两个容器中，分为两种类型的熟悉选项参数和非选项参数，选项参数使用 --开头
		CommandLineArgs commandLineArgs = new CommandLineArgs();
		for (String arg : args) {
			if (arg.startsWith("--")) {
				String optionText = arg.substring(2, arg.length());
				String optionName;
				String optionValue = null;
				if (optionText.contains("=")) {
					optionName = optionText.substring(0, optionText.indexOf('='));
					optionValue = optionText.substring(optionText.indexOf('=')+1, optionText.length());
				}
				else {
					optionName = optionText;
				}
				if (optionName.isEmpty() || (optionValue != null && optionValue.isEmpty())) {
					throw new IllegalArgumentException("Invalid argument syntax: " + arg);
				}
				commandLineArgs.addOptionArg(optionName, optionValue);
			}
			else {
				commandLineArgs.addNonOptionArg(arg);
			}
		}
		return commandLineArgs;
	}

public CommandLinePropertySource(T source) {
		super(COMMAND_LINE_PROPERTY_SOURCE_NAME, source);
	}

private ConfigurableEnvironment prepareEnvironment(
			SpringApplicationRunListeners listeners,
			ApplicationArguments applicationArguments) {
		//进来第一步先声明一个可配置的环境变量容器
		ConfigurableEnvironment environment = getOrCreateEnvironment();
		//然后配置它
		configureEnvironment(environment, applicationArguments.getSourceArgs());
		//然后发布给事件出去告诉所有listener 环境配置完成
		listeners.environmentPrepared(environment);
		//把环境绑定给springboot
		bindToSpringApplication(environment);
		if (!this.isCustomEnvironment) {
			environment = new EnvironmentConverter(getClassLoader())
					.convertEnvironmentIfNecessary(environment, deduceEnvironmentClass());
		}
		ConfigurationPropertySources.attach(environment);
		return environment;
	}

	private ConfigurableEnvironment getOrCreateEnvironment() {
		if (this.environment != null) {
			return this.environment;
		}
		switch (this.webApplicationType) {
		case SERVLET:
			return new StandardServletEnvironment();
		case REACTIVE:
			return new StandardReactiveWebEnvironment();
		default:
			return new StandardEnvironment();
		}
	}

@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()));
	}

configureEnvironment(environment,applicationArguments.getSourceArgs());

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

configurePropertySources(environment, args);

protected void configurePropertySources(ConfigurableEnvironment environment,
			String[] args) {
		MutablePropertySources sources = environment.getPropertySources();
		if (this.defaultProperties != null && !this.defaultProperties.isEmpty()) {
			sources.addLast(
					new MapPropertySource("defaultProperties", this.defaultProperties));
		}
		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));
			}
		}
	}

public static void main(String[] args) {
        SpringApplicationBuilder builder = new SpringApplicationBuilder();
        builder.properties(map);
        builder.run(Application.class,args);
    }

	protected Set<String> doGetActiveProfiles() {
		synchronized (this.activeProfiles) {
			if (this.activeProfiles.isEmpty()) {
				String profiles = getProperty(ACTIVE_PROFILES_PROPERTY_NAME);
				if (StringUtils.hasText(profiles)) {
					setActiveProfiles(StringUtils.commaDelimitedListToStringArray(
							StringUtils.trimAllWhitespace(profiles)));
				}
			}
			return this.activeProfiles;
		}
	}

protected <T> T getProperty(String key, Class<T> targetValueType, boolean resolveNestedPlaceholders) {
		if (this.propertySources != null) {
			for (PropertySource<?> propertySource : this.propertySources) {
				if (logger.isTraceEnabled()) {
					logger.trace("Searching for key '" + key + "' in PropertySource '" +
							propertySource.getName() + "'");
				}
				Object value = propertySource.getProperty(key);
				if (value != null) {
					if (resolveNestedPlaceholders && value instanceof String) {
						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;
	}