the servlet request.getRequestDispatcher ("index.jsp") Jump to jsp page without any reaction

Purpose you want to jump to in the servlet jsp page.

index.jsp page in the root directory , there is no 404 errors .

	public void doPost(HttpServletRequest request, HttpServletResponse response)
  			throws ServletException, IOException {
  		String path = "/index.jsp";
  		List<Books> all = null;
  		try{
  			all = DaoFactory.getIBookDaoInstance().findAll(" ");	
  		}catch(Exception e){
  			e.printStackTrace();
  		}finally{
  			
  		}
  		System.out.println("dd");
  		request.setAttribute("books", all);
  		request.getRequestDispatcher("/index.jsp").forward(request, response);
  		System.out.println("dd");
  		
  	}

I
entered directly in the browser on the servlet address, and then print it out

dd
dd

explanation middle request.getRequestDispatcher ("/ index.jsp"). forward (request, response); must have executed , but nothing happens. I ask why ?
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request.getRequestDispatcher("/index.jsp").forward(request, response);

server-side adjustment , the address bar will not change.
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request.getRequestDispatcher () is a request forwarded front page sharing a request, so the url will not change.
response.sendRedirect () is re-directed , before and after the page is not a request, so this will change .
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browser, enter the address after the transport servlet URL unchanged.
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find the reason , it seems to jump when the URL does not change , that shows the servlet address

		String sql = "select * from Books where bno like ? or bname like ? or bkind like ?";
  		this.pstmt = this.conn.prepareStatement(sql);
  		pstmt.setString(1,"%"+keyWord+"%");
  		pstmt.setString(2,"%"+keyWord+"%");
  		pstmt.setString(3,"%"+keyWord+"%");

this sentence out of the question , the above is corrected , because the query is not found reason
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saying landlord, I now have a problem is the servlet session where information is stored , and then jump to the jsp, jsp remove the session information and display , but my jsp pages have nothing, even the common words are not showing up , the problem is that the transition did not succeed because getRequestDispatcher or because of what ?
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suggestions about the session in the console output data ( can be output in a servlet on the inside ) , see if it is null. every one statement output look, look for the wrong reasons ,
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recommendations about the session in the console output data ( can be output in a servlet on the inside ) , see if it is null. every one statement output look, look for the wrong reasons ,  

saying it directly in the servlet output, then the output is just an ordinary word , not output the contents of the database , using netbeans own database , built Entity Bean class will automatically generate code, so I really do not know where I wrong. With the success of the students still can not write the same . Logically speaking, there is no problem fishes , do I have a problem netbeans what ? = . =

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request.getRequestDispatcher () is forwarded , forwarded to another servlet or jsp go, you following System.out.println ("dd"); also perform ? This code is a problem .
request.getRequestDispatcher () back to add a return; otherwise error
Similarly , response.sendRedirect back also add a return;

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know Thank you