update_jsp.java

这是一个图书馆管理系统的jsp代码

      out.write("              <td align=\"center\"><img src=\"F:\\example\\图书馆\\login/library4.png\" width=\"102\" height=\"5\" alt=\"\"></td>\r\n");
      out.write("            </tr>\r\n");
      out.write("            <tr>\r\n");
      out.write("              <td align=\"right\"><img src=\"F:\\example\\图书馆\\login/library3.png\" width=\"10\" height=\"10\" alt=\"\"></td>\r\n");
      out.write("              <td align=\"center\"><a href=\"search.jsp\">Search</a></td>\r\n");
      out.write("            </tr>\r\n");
      out.write("            <tr>\r\n");
      out.write("              <td align=\"right\">&nbsp;</td>\r\n");
      out.write("              <td align=\"center\"><img src=\"F:\\example\\图书馆\\login/library4.png\" width=\"102\" height=\"5\" alt=\"\"></td>\r\n");
      out.write("            </tr>\r\n");
      out.write("             <tr>\r\n");
      out.write("              <td align=\"right\"><img src=\"F:\\example\\图书馆\\login/library3.png\" width=\"10\" height=\"10\" alt=\"\"></td>\r\n");
      out.write("              <td align=\"center\"><a href=\"userpay.jsp\">Userpay</a></td>\r\n");
      out.write("            </tr>\r\n");
      out.write("            <tr>\r\n");
      out.write("              <td align=\"right\">&nbsp;</td>\r\n");
      out.write("              <td align=\"center\"><img src=\"F:\\example\\图书馆\\login/library4.png\" width=\"102\" height=\"5\" alt=\"\"></td>\r\n");
      out.write("            </tr>\r\n");
      out.write("             <tr>\r\n");
      out.write("              <td align=\"right\"><img src=\"F:\\example\\图书馆\\login/library3.png\" width=\"10\" height=\"10\" alt=\"\"></td>\r\n");
      out.write("              <td align=\"center\"><a href=\"update.jsp\">Update</a></td>\r\n");
      out.write("            </tr>\r\n");
      out.write("            <tr>\r\n");
      out.write("              <td align=\"right\">&nbsp;</td>\r\n");
      out.write("              <td align=\"center\"><img src=\"F:\\example\\图书馆\\login/library4.png\" width=\"102\" height=\"5\" alt=\"\"></td>\r\n");
      out.write("            </tr>\r\n");
      out.write("            <tr>\r\n");
      out.write("              <td width=\"20\" align=\"right\">&nbsp;</td>\r\n");
      out.write("              <td width=\"130\" align=\"center\">&nbsp;</td>\r\n");
      out.write("            </tr>\r\n");
      out.write("          </table></td>\r\n");
      out.write("        </tr>\r\n");
      out.write("        <tr>\r\n");
      out.write("          <td height=\"200\" valign=\"top\" bgcolor=\"#CCCCCC\">&nbsp;</td>\r\n");
      out.write("        </tr>\r\n");
      out.write("      </table></td>\r\n");
      out.write("     <td height=\"449\" align=\"center\" valign=\"middle\"><p class=\"style5\">You have succeeded in updating</p>\r\n");
      out.write("      <p class=\"style5\">Administrator!</p></td>\r\n");
      out.write("    </tr>\r\n");
      out.write("    <tr>\r\n");
      out.write("      <td bgcolor=\"#666666\">&nbsp;</td>\r\n");
      out.write("      <td><img src=\"F:\\example\\图书馆\\login/library2.png\" width=\"573\" height=\"40\" alt=\"\"></td>\r\n");
      out.write("    </tr>\r\n");
      out.write("  </table>\r\n");
      out.write("</form>\r\n");
      out.write("\r\n");
      out.write("\r\n");
      login.Library Library = null;
      synchronized (session) {
        Library = (login.Library) _jspx_page_context.getAttribute("Library", PageContext.SESSION_SCOPE);
        if (Library == null){
          Library = new login.Library();
          _jspx_page_context.setAttribute("Library", Library, PageContext.SESSION_SCOPE);
          out.write('\r');
          out.write('\n');
        }
      }
      out.write("\r\n");
      out.write("<center>\r\n");
      out.write("\r\n");

String id = Library.getid();
  int shouldreturndata=0,number=1;
  String title="",strsrd="",returnmoney="yes",returnmoney1="yes";//returndata1="",title1="";

try{
  Connection conn=Library.getConn();
  Statement stmt,stmt1;
   stmt = conn.createStatement();
   ResultSet rs1 = stmt.executeQuery("select * from borrowbook");
   while(rs1.next()){++number;}
   for(int i=1;i<=number;i++){
     ResultSet rs2 = stmt.executeQuery("select * from borrowbook where trailnumber ='" + i + "'");

//int trailnumber =Integer.parseInt(rs1.getString("trailnumber"));//用rs1.getInt()无法识别，尽管数据表数据是int型
  //PreparedStatement pstmt1 = conn.prepareStatement();

//  PreparedStatement pstmt3 = conn.prepareStatement("select * from borrowbook where id ='" + id + "'");

 //  ResultSet rs1 = stmt.executeQuery("select * from borrowbook where id ='" + id + "'");//在用户登陆时，判断用户是不是有超出借期的书没还，把相应纪录的overdata,fee,returnmoney改变，即在每次用户登陆时判断是否要罚款
  // out.println("<p>"+rs1.getString("studnetnumber")+"</p>");
   stmt1=conn.createStatement();//Resultset is closed，是指在一个rs正在循环时，使用这个rs所对应的stmt等，进行操作，产生的rs关闭，一个rs在没有结束时，他的stmt不能被再次使用
  while(rs2.next()){//无效游标有时指缺少rs1.next()

  int returndata=Integer.parseInt(rs2.getString("returndata"));//因为如果returndata为String型，无法判断null,所以用int,可判断0
    //out.println("<p>'"+returndata+"'</p>");
    strsrd=rs2.getString("shouldreturndata");
    //title=rs1.getString("title");
   shouldreturndata=Integer.parseInt(strsrd);
 //  out.println("<p>"+shouldreturndata+"</p>");

//out.println("<p>"+(new java.util.Date().getYear()*365 + new java.util.Date().getMonth()*31 + new java.util.Date().getDay())+"</p>");
  if(returndata==0 && (new java.util.Date().getYear()*365 + new java.util.Date().getMonth()*31 + new java.util.Date().getDay())>shouldreturndata)//new java.util.Date()获得系统当前时间，因为日期的相减比较工作很复杂，所以把日期型变量用get函数转化为相应的int型，在乘以权数，进行比较
{
  int overdata = (new java.util.Date().getYear()*365 + new java.util.Date().getMonth()*31 + new java.util.Date().getDay()) - shouldreturndata;
  //out.println("<p>"+overdata+"</p>");
  double feeperday = 0.01;
  double fee = feeperday*overdata;
  //   Statement stmt=conn.createStatement();

  stmt1.execute("update borrowbook set overdata = '" + overdata + "' where trailnumber ='" + i + "'");
  stmt1.execute("update borrowbook set fee = '" + fee + "' where trailnumber ='" + i + "'");
  stmt1.execute("update borrowbook set returnmoney = 'no' where trailnumber ='" + i + "'");
}
}
}
}catch (Exception ex){
          response.sendRedirect("fail.jsp");
ex.printStackTrace();}


      out.write("\r\n");
      out.write("</center>\r\n");
      out.write("</body>\r\n");
      out.write("</html>\r\n");
    } catch (Throwable t) {
      if (!(t instanceof SkipPageException)){
        out = _jspx_out;
        if (out != null && out.getBufferSize() != 0)
          out.clearBuffer();
        if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);
      }
    } finally {
      if (_jspxFactory != null) _jspxFactory.releasePageContext(_jspx_page_context);
    }
  }
}