容器的基本实现

XmlBeanFactory的解析

BeanFactory bf = new XmlBeanFactory(new ClassPathResource("beanFactoryTest.xml"));

上面代码的执行逻辑，如下：

title XmlBeanFactory 初始化时序图

bf(BeanFactoryTest)->+res(ClassPathResource):1. new ClassPathResource("beanFactory.xml")
res(ClassPathResource)-->-bf(BeanFactoryTest):2. resource:Resource
bf(BeanFactoryTest)->+xF(XmlBeanFactory):3. new XmlBeanFactory(resource)
xF(XmlBeanFactory)->+reader(XMLBeanDefinitionReader):3.1 loadBeanDefinitions(resource)
reader(XMLBeanDefinitionReader)-->-xF(XmlBeanFactory):3.2 loadBeanDefintionNum:int
xF(XmlBeanFactory)-->-bf(BeanFactoryTest):4. xF:BeanFactory

通过时序图我们可以一目了然的看到整个逻辑的处理顺序。在测试的例子中首先调用ClassPathResource的构造函数来构造Resource资源文件的实例对象，这样后续的资源处理中我们就可以用Resource提供的各种服务来操作了。

配置文件的封装

在JAVA中，将不同的资源抽象成URL，通过注册不同的handle(URLStreamHandler)来处理不同来源的资源读取逻辑，一般handle的类型使用不同的前缀（协议，Protocol）来识别，然而URL没有默认定义相对的ClassPath或ServletContext等资源的handle,我们需要了解URL的实现机制来注册自已的URLStreamHandler来解析特定的URL前缀。因而Spring对其内部使用的资源实现了自已的抽象结构：Resource接口来封装底层资源。

public interface InputStreamSource {
	InputStream getInputStream() throws IOException;
}

public interface Resource extends InputStreamSource {
	boolean exists();   //存在性
	boolean isReadable() ;  //可读性
	boolean isOpen();   //是否处于打开状态
	default boolean isFile();   //Determine whether this resource represents a file in a file system.
	URL getURL() throws IOException;  //Return a URL handle for this resource.
	URI getURI() throws IOException;   //Return a URI handle for this resource.
	File getFile() throws IOException;   //Return a File handle for this resource.
	default ReadableByteChannel readableChannel() throws IOException ;   //Return a {@link ReadableByteChannel}.
	long contentLength() throws IOException;   //Determine the content length for this resource.
	long lastModified() throws IOException;   //Determine the last-modified timestamp for this resource.
	Resource createRelative(String relativePath) throws IOException;   //Create a resource relative to this resource.
	@Nullable
	String getFilename();  //Determine a filename for this resource, i.e. typically the last
	String getDescription();   //用于在错误处理中的打印信息
}

资源文件处理的相关类图