为什么数据不能覆盖呢？

文件头上加：
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);

choose.jsp 文件获取的值是随我得选择改变而变化的，是正确的。
可就是writeinfo.jsp 通过session.getAttribute("..")获取的值始终是第一次的值，上面的方法我都试过了呀！

session.setAttribute("...",...);后把它OUT出来，然后运行多次，看每次都OUT出来都一样吗？这样你就知道错在哪里了?

choose.jsp 用以获取 html 文件中的选项值：

<%@ page contentType="text/html;charset=gb2312" %>
<%@ page import="java.io.*" session="true" autoFlush="true"%>
<%response.setHeader("Pragma","No-cache");
  response.setHeader("Cache-Control","no-cache");
  response.setDateHeader("Expires", 0);
%>
<html>
<head>
<title>dir</title>
<%
String  Dir=null;
        Dir=request.getParameter("foldheader");
if(session.getAttribute("foldheader")==null) session.setAttribute("foldheader",Dir);String  subname=null;
        subname=request.getParameter("sub");
if(subname!=null){if(session.getAttribute("sub")==null) session.setAttribute("sub",subname);}String  subsubname=null;
        subsubname=request.getParameter("subsub");
boolean subsubnameChecked=request.getParameter("subsub")!=null;
String checkOr;
if(subsubnameChecked==true)
{checkOr="yes";
  if(session.getAttribute("subsub")==null) session.setAttribute("subsub",subsubname);

}
else {checkOr="no";}
if(session.getAttribute("ifChecked")==null) session.setAttribute("ifChecked",checkOr);
%>
<jsp:forward page="showtree.jsp"/>
</body>
</html>writeinfo.jsp 提取刚才由 choose.jsp 设置的 session 变量值：<%@ page session="true" autoFlush="true"%>
<%@ page contentType="text/HTML;charset=gb2312" %>
<%response.setHeader("Pragma","No-cache");
  response.setHeader("Cache-Control","no-cache");
  response.setDateHeader("Expires", 0);
%>
<jsp:useBean id="transl" scope="session" class="regchk.Translate"/> <HTML>
<HEAD>
<TITLE>
将文件信息写入数据库
</TITLE>
</HEAD>
<BODY>
<%@ page language = "java"%>
<%@ page import = "java.util.*"%>
<%@ page import = "java.io.*"%>
<%@ page import = "javax.servlet.http.*"%>
<%@ page import = "javax.servlet.*"%>
<%@ page import = "java.sql.*"%>
<%
   String prelocation=null,
          location=null,
          branch=null,
          branch_conv=null,
          category=null,
          category_conv=null,
          subcategory=null,
          subcategory_conv=null;



    branch=(String)session.getAttribute("foldheader");
    branch_conv=new String(branch.getBytes("iso8859-1"),"GBK");
    category=(String)session.getAttribute("sub");
    category_conv=new String(category.getBytes("iso8859-1"),"GBK");
   String ifChecked=(String)session.getAttribute("ifChecked");
   if(ifChecked.equals("yes"))
   {  subcategory=(String)session.getAttribute("subsub");
      subcategory_conv=new String(subcategory.getBytes("iso8859-1"),"GBK");
      prelocation="uploadreal/"+branch+"/"+category+"/"+subcategory;
   }
   else
   { prelocation="uploadreal/"+branch+"/"+category;
   }
     location=transl.c(prelocation);
   String Year=(String)request.getParameter("year");
   String Month=(String)request.getParameter("month");
   String Date=(String)request.getParameter("date");
   if(session.getAttribute("Year")==null) session.setAttribute("Year",Year);
   if(session.getAttribute("Month")==null) session.setAttribute("Month",Month);
   if(session.getAttribute("Date")==null) session.setAttribute("Date",Date);

   String docuname=branch_conv+"_"+category_conv+"_"+keyword+"_"+Year+Month+Date+type;
   String docuname1=branch+"_"+category+"_"+keyword1+"_"+Year+Month+Date+type;
   String realname=transl.c(docuname1);
   String type=(String)request.getParameter("type");
   String keyword1=(String)request.getParameter("keyword");
   if(session.getAttribute("keyword")==null) session.setAttribute("keyword",keyword1);
   String keyword=new String(keyword1.getBytes("iso8859-1"),"GBK");
   String author=(String)request.getParameter("author");
   String author_conv=new String(author.getBytes("iso8859-1"),"GBK");
   String serial=(String)request.getParameter("serial");
   String serial_conv=new String(serial.getBytes("iso8859-1"),"GBK");
String driver = "sun.jdbc.odbc.JdbcOdbcDriver";
String connectString = "jdbc:odbc:DBTEST";
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection conn;
ResultSet rs;
String  sql = "INSERT INTO document(location,docuname,realname,draftdate,author,serial) VALUES('"+location+"','"+docuname+"','"+realname+"',GETDATE(),'"+author_conv+"','"+serial_conv+"')";    conn=DriverManager.getConnection(connectString);
    Statement stmt = conn.createStatement();
    stmt.executeUpdate(sql);
%>
摘要信息提交成功！请选择要上传的文件：<br>
<br>
<jsp:forward page="select.htm"/>
</BODY>
</HTML>
出现的问题是：
无论我后来在html文件中选取什么选项，branch、category、subcategory的值都保持为choose.jsp第一次从html文件中获取的值。
谢谢高手指点了。

答 kongxiangli(笑看红尘)：
每次都OUT出来都不一样，看来 session.setAttribute("...",...); 这个地方是没有问题的。

>if(session.getAttribute("foldheader")==null)
> session.setAttribute("foldheader",Dir);
第一次从html文件中获取的值一直都在session, session.getAttribute("foldheader")!=null, 所以第二, 三, 四....次沒有行session.setAttribute("foldheader",Dir);你明白什么是session 嗎?

调试易

为什么数据不能覆盖呢？

解决方案 »