jsp+servlet+mysql实现登录

package edu.ctgu.exer.servlet; import javax.servlet.RequestDispatcher; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import edu.ctgu.exer.dao.User; import edu.ctgu.exer.dao.UserDaoInterfaceImplements; public class LoginServlet extends HttpServlet { /** * */ private static final long serialVersionUID = 1L; public void service(HttpServletRequest request,HttpServletResponse response)throws ServletException,java.io.IOException { String errMsg = ""; //Servlet本身并不输出响应到客户端，因此必须将请求转发 RequestDispatcher rd; //获取请求参数 User user = new User(); String name = request.getParameter("name"); String password = request.getParameter("password"); user.setName(name); user.setPassword(password); try { UserDaoInterfaceImplements udii = new UserDaoInterfaceImplements(); int result = udii.select(user); if (result == 1){ //获取session对象 HttpSession session = request.getSession(true); //设置session属性，跟踪用户会话状态 session.setAttribute("username" ,name); //获取转发对象 rd = request.getRequestDispatcher("/welcome.jsp"); //转发请求 rd.forward(request,response); }else if(result == 0){ //用户名和密码不匹配时 errMsg += "您的用户名密码不符合,请重新输入"; }else{ //用户名不存在时 errMsg += "您的用户名不存在,请先注册"; } } catch (Exception e) { e.printStackTrace(); } //如果出错，转发到重新登录 if (errMsg != null && !errMsg.equals("")) { rd = request.getRequestDispatcher("/login.jsp"); request.setAttribute("err" , errMsg); rd.forward(request,response); } } }