一：Spring源码解析之prepareRefresh()_spring preparerefresh()源码解读-CSDN博客

本文链接：https://blog.csdn.net/sbl19940819/article/details/127924276

本文详细解析了Spring框架中AbstractApplicationContext类的refresh方法的具体实现，包括容器启动的时间记录、关闭及激活标志位的设置等关键步骤，并介绍了环境配置对象的创建与验证过程。

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AbstractApplicationContext -> refresh()

1. 功能概述：

设置容器启动时间
设置容器关闭标志位
设置激活标志位
记录轨迹日志
初始化属性资源（空，留给子类实现）
创建并获取环境对象，校验
准备监听器和事件的集合对象，默认为空

2. 源码

	/**
	 * Prepare this context for refreshing, setting its startup date and
	 * active flag as well as performing any initialization of property sources.
	 */
	protected void prepareRefresh() {
		// Switch to active.
		// 设置容器启动的时间
		this.startupDate = System.currentTimeMillis();
		// 容器的关闭标志位
		this.closed.set(false);
		// 容器的激活标志位
		this.active.set(true);
		// 记录日志
		if (logger.isDebugEnabled()) {
			if (logger.isTraceEnabled()) {
				logger.trace("Refreshing " + this);
			}
			else {
				logger.debug("Refreshing " + getDisplayName());
			}
		}
		// Initialize any placeholder property sources in the context environment.
		// 留给子类覆盖，初始化属性资源
		initPropertySources();

		// Validate that all properties marked as required are resolvable:
		// see ConfigurablePropertyResolver#setRequiredProperties
		// 创建并获取环境对象，验证需要的属性文件是否都已经放入环境中
		getEnvironment().validateRequiredProperties();

		// Store pre-refresh ApplicationListeners...
		// 判断刷新前的应用程序监听器集合是否为空，如果为空，则将监听器添加到此集合中
		if (this.earlyApplicationListeners == null) {
			this.earlyApplicationListeners = new LinkedHashSet<>(this.applicationListeners);
		}
		else {
			// Reset local application listeners to pre-refresh state.
			// 如果不等于空，则清空集合元素对象
			this.applicationListeners.clear();
			this.applicationListeners.addAll(this.earlyApplicationListeners);
		}
		// Allow for the collection of early ApplicationEvents,
		// to be published once the multicaster is available...
		// 创建刷新前的监听事件集合
		this.earlyApplicationEvents = new LinkedHashSet<>();
	}

2.1 细节解析

2.1.1 getEnvironment()

AbstactApplicationContext.java

@Override
	public ConfigurableEnvironment getEnvironment() {
		if (this.environment == null) {
			this.environment = createEnvironment();
		}
		return this.environment;
	}

//============================
protected ConfigurableEnvironment createEnvironment() {
		return new StandardEnvironment();
	}

类StandardEnvironment继承自AbstractEnvironment，创建对象，执行父类的构造方法

public class StandardEnvironment extends AbstractEnvironment

//=======================
public AbstractEnvironment() {   
customizePropertySources(this.propertySources);
}

//留给子类去扩展
protected void customizePropertySources(M
utablePropertySources propertySources) {
}

StandardEnvironment.java

// 父类定义的方法，子类扩展的接口
	@Override
	protected void customizePropertySources(MutablePropertySources propertySources) {
		propertySources.addLast(
				new PropertiesPropertySource(SYSTEM_PROPERTIES_PROPERTY_SOURCE_NAME, getSystemProperties()));
		propertySources.addLast(
				new SystemEnvironmentPropertySource(SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME, getSystemEnvironment()));
	}