标签：set adl mvc 技术 方法 throw 调用 destory ssi
<!-- 此监听器是监听HttpRequest对象，方便ContextHolderUtils程序调用HttpRequest对象 --> <listener> <description>request监听器</description> <listener-class>org.springframework.web.context.request.RequestContextListener</listener-class> </listener>
public class RequestContextListener implements ServletRequestListener {
private static final String REQUEST_ATTRIBUTES_ATTRIBUTE =
RequestContextListener.class.getName() + ".REQUEST_ATTRIBUTES";
// 在请求进入的时候，初始化变量放入ThreadLocal<T>中
@Override
public void requestInitialized(ServletRequestEvent requestEvent) {
//判定当前的requetEvent中获取的ServletRequest()对象是否是HttpServletRequet对象
if (!(requestEvent.getServletRequest() instanceof HttpServletRequest)) {
throw new IllegalArgumentException(
"Request is not an HttpServletRequest: " + requestEvent.getServletRequest());
}
//强制转型为 HttpServletRequest
HttpServletRequest request = (HttpServletRequest) requestEvent.getServletRequest();
// ServletRequestAttributes 保存了HttpServletRequet、Response、Session等变量
ServletRequestAttributes attributes = new ServletRequestAttributes(request);
request.setAttribute(REQUEST_ATTRIBUTES_ATTRIBUTE, attributes);
LocaleContextHolder.setLocale(request.getLocale());
//RequestContextHolder里面有一个ThreadLocal，当前线程共享
RequestContextHolder.setRequestAttributes(attributes);
}
//在请求被销毁的时候，将在初始化时候的ThreadLocal变量清空。
@Override
public void requestDestroyed(ServletRequestEvent requestEvent) {
...
}
}
public abstract class RequestContextHolder {
//ThreadLocal<T>变量用于保存当前线程的共享变量
private static final ThreadLocal<RequestAttributes> requestAttributesHolder =
new NamedThreadLocal<RequestAttributes>("Request attributes");
private static final ThreadLocal<RequestAttributes> inheritableRequestAttributesHolder =
new NamedInheritableThreadLocal<RequestAttributes>("Request context");
/**
* 将线程中的共享变量清除掉，会在RequetContextListner的destory()方法中调用。
*/
public static void resetRequestAttributes() {
//清空变量
requestAttributesHolder.remove();
inheritableRequestAttributesHolder.remove();
}
//过渡方法
public static void setRequestAttributes(RequestAttributes attributes) {
setRequestAttributes(attributes, false);
}
// 核心的方式：将RequetAttrubutes(Request/Response/Session)放入到ThreadLocal<T>中进行共享
public static void setRequestAttributes(RequestAttributes attributes, boolean inheritable) {
if (attributes == null) {
resetRequestAttributes();
}
else {
if (inheritable) {
inheritableRequestAttributesHolder.set(attributes);
requestAttributesHolder.remove();
}
else {
requestAttributesHolder.set(attributes);
inheritableRequestAttributesHolder.remove();
}
}
}
public class ServletRequestAttributes extends AbstractRequestAttributes {
private final HttpServletRequest request;
private HttpServletResponse response;
private volatile HttpSession session;
private final Map<String, Object> sessionAttributesToUpdate = new ConcurrentHashMap<String, Object>(1);
}
HttpServletRequest request =((ServletRequestAttributes)RequestContextHolder.getRequestAttributes()).getRequest();
http://www.cnblogs.com/LiuChunfu/p/7067828.html
由SpringMVC中RequetContextListener说起
标签：set adl mvc 技术 方法 throw 调用 destory ssi
原文地址：http://www.cnblogs.com/softidea/p/7068196.html
