Java到MySQL的JDBC连接问题

Question

I'm new with getting a java applet to connect to a mysql database. This is my first time attempting to do so.

I've researched a lot and have seen lots of tutorials, but I'm still facing problems. Since my java applet goes to a browser, I did sign it. I've also been using jdbc and the jar file has been imported properly to my library.

I've also been using 000webhost.com and have been trying to connect to the database from both the IDE and the browser. I also got two of my friends to help me. One of them had to go early and the other don't know where I went wrong.

Here is my codes: http://prntscr.com/oagfi

I've come to the conclusion that the DriverManager.getConnection(...) is whats giving me problems.

The error reads... http://prntscr.com/oaetz

I have also tried looking up the cause but still no luck.

Is there anything I can do to fix this problem? I'm curious of what this cause mean and why I'm having trouble.

Answer 1

如果您使用免费的000webhost帐户，则无法在主机帐户之外访问数据库。

Answer 2

Check the version of JDBC Connector you are using. Also following link will help you to do JDBC Connection -

Connect Java to a MySQL database

Answer 3

Are you behind a firewall/proxy server? If so, does it permit outgoing connections on port 3306 you're using? This was a problem I had once, our corporate firewall was so crippled we could only talk out via the http /https ports.

Answer 4

From Applet (if my memory not fail), you must use Signed code and/or you can only connect to remotehost from Applet was downloaded... if not, security exceptions are throwed. (applets run on a limited/restricted sandbox)

Answer 5

        /* RegistrationDAO*/


        /*
         * To change this template, choose Tools | Templates
         * and open the template in the editor.
         */
        package com.tcs.ignite.connectionname.DAO;

        import com.tcs.ignite.connectionname.bean.Register;
        import com.tcs.ignite.connectionname.util.Eyeconnection;
        import java.sql.Connection;
        import java.sql.PreparedStatement;
        import java.sql.ResultSet;

        public class RegisterDAO {
            private Connection connection;
             private connectionnamecon;

            public RegisterDAO() {
                con = new connectionname();
            }

            public boolean insertRecords(Register rg) throws Exception {

                connection = con.openConnection();

                String select="select * from register";
                PreparedStatement ps=connection.prepareStatement(select);
                ResultSet rs=ps.executeQuery();
                while(rs.next())
                {
                    String email=rs.getString("user_email");
                    if(rg.getUser_email().equals(email))
                    {
                        return false;
                     }
                }
               ps.close();



                String query = "insert into register(user_Fname,user_Lname,password,confirm_pass,contact_no,user_email,user_address,user_pincode) VALUES (?,?,?,?,?,?,?,?)";
                ps = connection.prepareStatement(query);

                ps.setString(1, rg.getUser_Fname());
                ps.setString(2, rg.getUser_Lname());
                ps.setString(3, rg.getPassword());
                ps.setString(4, rg.getConfirm_pass());
                ps.setString(5, rg.getContact_no());
                ps.setString(6, rg.getUser_email());
                ps.setString(7, rg.getUser_address());
                ps.setString(8,rg.getUser_pincode());

                int rowcount = ps.executeUpdate();
                con.closeConnection();
                if (rowcount == 0) {
                    return false;
                } else {
                    return true;
                }
            }
        }

    /*
    RegistrationManager*/
     */
    package com.tcs.ignite.connectionname.Manager;

    import com.tcs.ignite.connectionname.DAO.RegisterDAO;
    import com.tcs.ignite.connectionname.bean.Register;


    public class RegisterManager {
         public boolean insertManager(Register rg) throws Exception {

            RegisterDAO regdao = new RegisterDAO();
            boolean result = regdao.insertRecords(rg);
            if(result==true)
            {
                return true;
            }
            else
            {
                return false;
            }
        }

    }
 /*RegistrationServlet*/

     protected void doPost(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {

            response.setContentType("text/html;charset=UTF-8");
            PrintWriter out = response.getWriter();
            try {

              Register reg=new Register();

              reg.setUser_Fname(request.getParameter("firstname"));
              reg.setUser_Lname(request.getParameter("lastname"));
              reg.setPassword(request.getParameter("password"));
              reg.setConfirm_pass(request.getParameter("confirm_password"));
              reg.setContact_no(request.getParameter("mobile"));
              reg.setUser_email(request.getParameter("email"));
              reg.setUser_address(request.getParameter("address"));
              reg.setUser_pincode(request.getParameter("pincode"));




              RegisterManager regManager=new RegisterManager();
              if(regManager.insertManager(reg)){
    //               RequestDispatcher requestDispatcher= request.getRequestDispatcher("TCSBLUE.jsp");
    //               requestDispatcher.forward(request, response);
                  HttpSession session = request.getSession(true);
                   session.setAttribute("loginid", reg.getUser_email());
                   //out.print(session.getAttribute("loginid"));
                  out.write("Successfully Registered...");
              }
              else
              {
    //              RequestDispatcher requestDispatcher= request.getRequestDispatcher("Error.jsp");
    //               requestDispatcher.forward(request, response);
                  out.write("Something is going wrong....");
              }
            }
            catch(Exception ex)
            {
                Logger.getLogger(Connection.class.getName()).log(Level.SEVERE, null, ex);
            }
            finally {            
                out.close();
            }

        }