用ajax写用户名验证时，在servlet写了个跳转语句不能执行

public void doPost(HttpServletRequest request, HttpServletResponse response)

			throws ServletException, IOException {

		request.setCharacterEncoding("utf-8");

		response.setContentType("text/html");

		UserDao ud=new UserDao();

		String username=request.getParameter("user");

		String userpassword=request.getParameter("pwd");

		boolean flag=ud.sel(username);

		System.out.println(username);

		System.out.println(userpassword);

		System.out.println(flag);

		PrintWriter out = response.getWriter();

		if(flag){

			out.print("The user name has been registered!");

		}else{

			out.print("<script>window.location.href='login.jsp';</script>");

			//response.sendRedirect("login.jsp");

		}

	}

用out.print("<script>window.location.href='login.jsp';</script>");显示

用response.sendRedirect("login.jsp");这个显示

------解决方案--------------------
再客户端跳转，服务端跳转ajax不会理会的

// out.print("<script>window.location.href='login.jsp';</script>");

 out.print("1");

if(ajaxobj.responseText=='1')window.location='login.jsp'