public class LoginServlet extends HttpServlet {
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private DataBase database = null;
    //初始化函数
    public void init() throws ServletException {
        database = new DataBase();
    }
    //处理get请求方法
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }
    //处理post请求方法
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        HttpSession session = request.getSession();       //获取用户当前会话
        String username = "";                            
        String password = "";
        String page = null;

        if(request.getParameter("txtUserName") != null)
            username = request.getParameter("txtUserName");  //获取用户名
        if(request.getParameter("txtPassword") != null)
            password = request.getParameter("txtPassword");  //获取密码
        //判断用户名、密码是否匹配
        boolean temp = false;
        //System.out.println(username + ", " + password);
        Connection con = database.getConnection();
        temp = DBUtilitya.isValid(con, username, password);
        //关闭数据库连接
        database.closeConnection(con);

        if(temp){
            InfoItem infoitem = null;
            Connection con2 = database.getConnection();
            infoitem = DBUtilitya.getUser(con2, username);
            database.closeConnection(con2);
            //将用户信息对象InfoItem存储在session对象当中
            session.setAttribute("infoitem",infoitem);
            //如果用户通过验证，则返回用户有关信息
            page = "showinfo.jsp";
        } else{
            //如果验证失败，则显示验证失败页面
            page = "errorpage.jsp";
        }
        //重定向到相应的页面
        response.sendRedirect(page);
        return;
    }
}

public class DBUtilitya {
    //判断用户名、密码是否正确
    public static boolean isValid(Connection con, String username, String userpwd){
        PreparedStatement prepStmt = null;
        ResultSet rs = null;                //存储查询结果
        String selectStatement = "select * from userinfo1 where  username='" +username+"' and userpwd = '" +userpwd+"' ";
        boolean temp = false;
        try{
           prepStmt = con.prepareStatement(selectStatement);
           prepStmt.setString(1,username);
           prepStmt.setString(2,userpwd);
           rs = prepStmt.executeQuery();     //查询数据库并返回结果记录集
           if (rs.next())                    //数据库里含有此用户名、密码对则返回true
              temp = true;
           else
              temp = false;                  //否则返回false,用户名、密码不匹配
           rs.close();
           prepStmt.close();
        }catch(Exception e){
           e.printStackTrace();
        }
        return temp;                         //返回验证结果
    }
    //根据用户名从数据库中获取用户的注册信息
    public static InfoItem getUser(Connection con, String username){
        PreparedStatement prepStmt = null;
        ResultSet rs = null;                 //结果记录集合
        InfoItem infoitem = null;
        String queryString = "select username,roomnumber1,roomnumber2, roomnumber3, roomnumber4 from userinfo1 where username='" +username+"'";
        try{
           prepStmt = con