@WebServlet(urlPatterns = "/*",loadOnStartup = 0)
public class DispatcherServlet extends HttpServlet {@Overrideprotected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {...}
}

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;public class ServletHelper {private static final Logger LOGGER = LoggerFactory.getLogger(ServletHelper.class);/*** 使每个线程独自拥有一份ServletHelper实例*/private static final ThreadLocal<ServletHelper> SERVLET_HELPER_HOLDER = new ThreadLocal<ServletHelper>();private HttpServletRequest request;private HttpServletResponse response;public ServletHelper(HttpServletRequest request, HttpServletResponse response) {this.request = request;this.response = response;}/*** 初始化* @param request* @param response*/public static void init(HttpServletRequest request,HttpServletResponse response){SERVLET_HELPER_HOLDER.set(new ServletHelper(request,response));}/*** 销毁*/public static void destroy(){SERVLET_HELPER_HOLDER.remove();}/*** 获取Request对象* @return*/private static HttpServletRequest getRequest(){return SERVLET_HELPER_HOLDER.get().request;}/*** 获取Response对象* @return*/private static HttpServletResponse getResponse(){return SERVLET_HELPER_HOLDER.get().response;}/*** 获取Session对象* @return*/private static HttpSession getSession(){return getRequest().getSession();}/*** 获取ServletContext对象* @return*/private static ServletContext getContext(){return getRequest().getServletContext();}
}

    /*** 将属性放入Request中* @param key* @param val*/public static void setRequestAttribute(String key,Object val){getRequest().setAttribute(key,val);}/*** 获取Request中的属性* @param key* @param <T>* @return*/public static <T> T getRequestAttribute(String key){return (T) getRequest().getAttribute(key);}/*** 从Request中移除属性* @param key*/public static void removeRequestAttribute(String key){getRequest().removeAttribute(key);}/*** 重定向* @param location*/public static void sendRedirect(String location){try {getResponse().sendRedirect(location);} catch (IOException e) {LOGGER.error("redirect failure",e);}}/*** 将属性放入Session中* @param key* @param val*/public static void setSessionAttribute(String key,Object val){getSession().setAttribute(key,val);}/*** 获取Session中的属性* @param key* @param <T>* @return*/public static <T> T getSessionAttribute(String key){return (T) getSession().getAttribute(key);}/*** 移除Session中的属性* @param key*/public static void removeSessionAttribute(String key){getSession().removeAttribute(key);}/*** 使Session失效*/public static void invalidateSession(){getSession().invalidate();}

protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {ServletHelper.init(req,resp);   //使每个线程都有独立的request和responsetry {/****/}finally {ServletHelper.destroy();}}