在 SpringBoot 启动过程中很重要的一步就是刷新上下文
org.springframework.boot.SpringApplication#refreshContext
org.springframework.context.support.AbstractApplicationContext#postProcessBeanFactory
Web 应用的上下文主要由WebApplicationContextUtils工具类来负责，在下面的方法中
org.springframework.web.context.support.WebApplicationContextUtils#registerWebApplicationScopes(org.springframework.beans.factory.config.ConfigurableListableBeanFactory, javax.servlet.ServletContext)
其中就对DefaultListableBeanFactory注册了ServletRequest的依赖处理
beanFactory.registerResolvableDependency(ServletRequest.class, new RequestObjectFactory());
private static class RequestObjectFactory implements ObjectFactory<ServletRequest>, Serializable {
@Override
public ServletRequest getObject() {
return currentRequestAttributes().getRequest();
}
@Override
public String toString() {
return "Current HttpServletRequest";
}
}
private static ServletRequestAttributes currentRequestAttributes() {
RequestAttributes requestAttr = RequestContextHolder.currentRequestAttributes();
if (!(requestAttr instanceof ServletRequestAttributes)) {
throw new IllegalStateException("Current request is not a servlet request");
}
return (ServletRequestAttributes) requestAttr;
}
public static RequestAttributes getRequestAttributes() {
RequestAttributes attributes = requestAttributesHolder.get();
if (attributes == null) {
attributes = inheritableRequestAttributesHolder.get();
}
return attributes;
}
private static final ThreadLocal<RequestAttributes> requestAttributesHolder =
new NamedThreadLocal<RequestAttributes>("Request attributes");
每次请求都会经过
org.springframework.web.filter.RequestContextFilter
其中会设置
@Override
protected void doFilterInternal(
HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
ServletRequestAttributes attributes = new ServletRequestAttributes(request, response);
initContextHolders(request, attributes);
try {
filterChain.doFilter(request, response);
}
finally {
resetContextHolders();
if (logger.isDebugEnabled()) {
logger.debug("Cleared thread-bound request context: " + request);
}
attributes.requestCompleted();
}
}
private void initContextHolders(HttpServletRequest request, ServletRequestAttributes requestAttributes) {
LocaleContextHolder.setLocale(request.getLocale(), this.threadContextInheritable);
RequestContextHolder.setRequestAttributes(requestAttributes, this.threadContextInheritable);
if (logger.isDebugEnabled()) {
logger.debug("Bound request context to thread: " + request);
}
}
private void resetContextHolders() {
LocaleContextHolder.resetLocaleContext();
RequestContextHolder.resetRequestAttributes();
}
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor#postProcessPropertyValues
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor#findAutowiringMetadata
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.AutowiredFieldElement#inject
org.springframework.beans.factory.support.DefaultListableBeanFactory#resolveDependency
