Spring MVC中如何通过RequestContextHolder类获取HttpServletRequest和HttpSession

package com.microfocus.g11n.openl10n.utils;

import com.hp.ccue.identity.user.idm.domain.IdmUser;
import com.microfocus.g11n.openl10n.constants.GlobalConstants;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpSession;

public class CurrentSession {
public static HttpSession session() {
ServletRequestAttributes attr = (ServletRequestAttributes) RequestContextHolder.currentRequestAttributes();
return attr.getRequest().getSession(false);
}

public static IdmUser getCurrentUser(){
ServletRequestAttributes attr = (ServletRequestAttributes) RequestContextHolder.currentRequestAttributes();

return (IdmUser)attr.getRequest().getSession(false).getAttribute(GlobalConstants.CURRENT_USER);
}

public static String getCurrentUserID(){
ServletRequestAttributes attr = (ServletRequestAttributes) RequestContextHolder.currentRequestAttributes();

return ((IdmUser)attr.getRequest().getSession(false).getAttribute(GlobalConstants.CURRENT_USER)).getId();
}
}