高分求援 报错java.lang.NullPointerException

高分求助 报错java.lang.NullPointerException
servlet
   
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
  this.doPost(request, response);
}
 
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
  String action=request.getParameter("action");
  if(action==null)
  {
  action="";
  }
  if(action.equals("add"))
  {
  this.addnews(request, response);
  }
}

public void addnews(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException 
  {
  RequestDispatcher rd=null;
  CNews cmgbean=new CNews();
  CNewsdao cmgdao=new CNewsdao();
  cmgbean.setStr_NTitle(trans.toChinese(request.getParameter("ntitle")));
  cmgbean.setStr_NTime(trans.toChinese(request.getParameter("ntime")));
  cmgbean.setStr_NContent(trans.toChinese(request.getParameter("ncontent")));
  boolean mark=cmgdao.operateNews("add",cmgbean);
  if(!mark)
  {
  System.out.println("<script>alert('发布失败！！')</script>");
  rd=request.getRequestDispatcher("../admin/login.jsp");
  rd.forward(request, response);
  }  
  else
  {
  response.sendRedirect("../admin/message.jsp");
  }  
 
 
  }
}


数据库操作类
  public boolean operateNews(String operation,CNews single)
{
String sql=null;
if(operation.equals("add"))
{  
sql="insert into News values('"+single.getStr_NTitle()+"','"+single.getStr_NTime()+"','"+single.getStr_NContent()+"')";
//sql="insert into News values('"+single.getStr_NContent()+"','"+single.getStr_NTime()+"','"+single.getStr_NTitle()+"')";
}
if(operation.equals("modify"))
{
sql="update News set NTime='"+single.getStr_NTime()+"',NTitle='"+single.getStr_NTitle()+"',NContent='"+single.getStr_NContent()+"' where NId='"+single.getInt_Id()+"'";
}
if(operation.equals("delete"))
{
sql="delete from News where NId='"+single.getInt_Id()+"'";
}
boolean flag=connect.executeUpdate(sql);
return flag;
}





------解决方案--------------------
web.xml贴出来看看
------解决方案--------------------

探讨

boolean flag=connect.executeUpdate(sql);

------解决方案--------------------
boolean flag=connect.executeUpdate(sql);

connect.executeUpdate(sql)的返回值是影响的行数，怎么能用boolean接收呢？
------解决方案--------------------
at com.dao.CNewsdao.operateNews(CNewsdao.java:33)

很明显CNewsdao.java类的33行代码出错，在此类的operateNews方法中，可以去定位下那行代码，
看是调用其它方法还是方法内的错误。
------解决方案--------------------
唉！又是空指针···