jsp+javabean+sqlServer做的一个购物车

package com.yxq.servlet; import java.io.IOException; import java.io.PrintWriter; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import javax.servlet.RequestDispatcher; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import com.yxq.bean.SingleObject; public class Buy extends HttpServlet { private Map havemap=new HashMap(); protected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException { doPost(request,response); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { HttpSession session=request.getSession(); String sessionID=session.getId(); int order=-1; String strorder=request.getParameter("list_order"); try{ order=Integer.parseInt(strorder); }catch(NumberFormatException e){ order=-1; } if(order==-1){ System.out.println("请选择商品！"); }else{ List currentlist=(ArrayList)session.getAttribute("currentlist"); if(currentlist!=null){ SingleObject select=(SingleObject)(currentlist.get(order)); int selectId=select.getId(); havemap=(HashMap)session.getServletContext().getAttribute("havemap"); if(havemap!=null&&havemap.size()!=0){ if(havemap.containsKey(selectId)){ synchronized(havemap){ int rem=(Integer)havemap.get(selectId); int exist=0; exist=rem-1; if(exist<0){ select.setMessage("库存已空！"); select.setHave(0); currentlist.set(order,select); session.setAttribute("currentlist",currentlist); } else{ havemap.put(selectId,exist); session.getServletContext().setAttribute("havemap",havemap); SingleObject buysingle=null; Map carmap=(HashMap)session.getAttribute("carmap"); /*** 如果购物车为空 ***/ if(carmap==null||carmap.size()==0){ carmap=new HashMap(); buysingle=new SingleObject(); buysingle.setId(selectId); buysingle.setName(select.getName()); buysingle.setPrice(select.getPrice()); buysingle.setTruehave(select.getTruehave()); buysingle.setBuyN(1); buysingle.setBuyMoney(buysingle.getBuyN()*buysingle.getPrice()); buysingle.setHave(exist); carmap.put(selectId,buysingle); } /*** 如果购物车不为空 ***/ else{ /*** 如果购物车已存在选中的物品 ***/ if(carmap.containsKey(selectId)){ buysingle=(SingleObject)carmap.get(selectId); buysingle.setBuyN(buysingle.getBuyN()+1); buysingle.setBuyMoney(buysingle.getPrice()*buysingle.getBuyN()); buysingle.setHave(exist); carmap.put(selectId,buysingle); } /*** 如果购物车不存在选中的物品 ***/ else{ buysingle=new SingleObject(); buysingle.setId(selectId); buysingle.setName(select.getName()); buysingle.setPrice(select.getPrice()); buysingle.setTruehave(select.getTruehave()); buysingle.setBuyN(1); buysingle.setBuyMoney(buysingle.getBuyN()*buysingle.getPrice()); buysingle.setHave(exist); carmap.put(selectId,buysingle); } } //购物车不为空 session.setAttribute("carmap",carmap); Map usermap=(HashMap)session.getServletContext().getAttribute("usermap"); usermap.put(sessionID,carmap); session.getServletContext().setAttribute("usermap",usermap); } //库存不为空 } //synchronized } //if(havemap.containsKey(selectId)) else{select.setMessage("未知库存量！"); } } //if(havemap!=null&&havemap.size()!=0) else{select.setMessage("HashMap库存表空！"); } } //if(currentlist!=null) else{System.out.println("列表为空！");} } RequestDispatcher rd=request.getRequestDispatcher("/shop/preindex"); rd.forward(request,response); } }