转发特点: 1.只有1次请求 2.地址栏地址不变,显示上个页面的地址 3.请求域内数据不会丢失
重定向特点: 1.有2次或多次请求 2.地址栏地址会变化,显示新页面的地址 3.请求域内数据会丢失,因为是第2次请求
代码示例
<% String uName = request.getParameter("userName"); String pwd = request.getParameter("pwd"); Connection conn = DBHelper.conn(); PreparedStatement ps = null; ResultSet rs = null; String sql = "select * from u_ser where U_name='" + uName + "'and pwd='" + pwd + "'"; try { ps = conn.prepareStatement(sql); rs = ps.executeQuery(); if (rs.next()) { session.setAttribute("userName", uName); response.sendRedirect("login2.jsp");//重定向 } else { request.setAttribute("msg", "账号或密码有误"); request.getRequestDispatcher("index.jsp").forward(request, response);//转发 } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { DBHelper.close(conn, ps, rs); } %>