简单的注册登录页面（jsp+servlet+jdbc+mysql）

package com.szx.jnmc; import java.io.IOException; import java.io.PrintWriter; import java.sql.ResultSet; import java.sql.SQLException; import java.text.SimpleDateFormat; import java.util.Date; import javax.servlet.RequestDispatcher; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.Cookie; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; /** * Servlet implementation class LoginServlet */ @WebServlet("/LoginServlet") public class LoginServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public LoginServlet() { super(); // TODO Auto-generated constructor stub } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub doPost(request,response); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub request.setCharacterEncoding("GBK"); response.setContentType("text/html;charset = GBK"); PrintWriter out = response.getWriter(); String username = request.getParameter("username"); String userpass = request.getParameter("userpass"); ServletContext ctx = request.getServletContext(); String server = ctx.getInitParameter("server"); String dbname = ctx.getInitParameter("dbname"); String dbuser = ctx.getInitParameter("dbuser"); String dbpwd = ctx.getInitParameter("dbpwd"); DBOper db = new DBOper(); db.getConn(server, dbname, dbuser, dbpwd); String sql = "SELECT username,userpass,role FROM tb_user WHERE username = ? AND userpass = ?"; ResultSet rs = db.executeQuery(sql,new String[]{username,userpass}); try { if(rs != null && rs.next()){ HttpSession session = request.getSession(); session.setAttribute("username",username); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss"); String logtime = sdf.format(new Date()); session.setAttribute("logtime",logtime); Cookie cookie = new Cookie("username",username); cookie.setMaxAge(60*60*24*30); response.addCookie(cookie); RequestDispatcher dispatcher = request.getRequestDispatcher("MainServlet"); dispatcher.forward(request,response); }else{ out.print("登录失败"); out.print("<br><a href = 'login.jsp'>重新登陆</a>"); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public void init()throws ServletException { } }