Java - JDBC driver and MySQL database connection issues

Question

Ok - I found the driver version that goes with the database.. however now I get the following.

Got an exception! Communications link failure due to underlying exception:

** BEGIN NESTED EXCEPTION **

java.net.ConnectException MESSAGE: Connection timed out: connect

STACKTRACE:

java.net.ConnectException: Connection timed out: connect at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333) at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366) at java.net.Socket.connect(Socket.java:525) at java.net.Socket.connect(Socket.java:475) at java.net.Socket.(Socket.java:372) at java.net.Socket.(Socket.java:215) at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:256) at com.mysql.jdbc.MysqlIO.(MysqlIO.java:271) at com.mysql.jdbc.Connection.createNewIO(Connection.java:2771) at com.mysql.jdbc.Connection.(Connection.java:1555) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:285) at java.sql.DriverManager.getConnection(DriverManager.java:582) at java.sql.DriverManager.getConnection(DriverManager.java:185) at freelancebilling app.customerInfoUI.jButton1MouseClicked(customerInfoUI.java:221) at freelancebillingapp.customerInfoUI.access$000(customerInfoUI.java:12) at freelancebillingapp.customerInfoUI$1.mouseClicked(customerInfoUI.java:59) at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:253) at java.awt.Component.processMouseEvent(Component.java:6266) at javax.swing.JComponent.processMouseEvent(JComponent.java:3255) at java.awt.Component.processEvent(Component.java:6028) at java.awt.Container.processEvent(Container.java:2041) at java.awt.Component.dispatchEventImpl(Component.java:4630) at java.awt.Container.dispatchEventImpl(Container.java:2099) at java.awt.Component.dispatchEvent(Component.java:4460) at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4574) at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4247) at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168) at java.awt.Container.dispatchEventImpl(Container.java:2085) at java.awt.Win dow.dispatchEventImpl(Window.java:2475) at java.awt.Component.dispatchEvent(Component.java:4460) at java.awt.EventQueue.dispatchEvent(EventQueue.java:599) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

** END NESTED EXCEPTION **

Last packet sent to the server was 1 ms ago.

Answer 1

This may not solve it, but it tells you that someone else has had this problem.

Make sure you have the precise version of JDBC driver to match your version of MySQL.

I would strongly urge you to rewrite your code more like this. You aren't closing resources properly at all.

Adapt it to your own needs. I created a local MySQL database on my machine and added a customer table. It worked just fine.

package persistence;

import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

public class DatabaseUtils
{
    private static final String URL = "jdbc:mysql://localhost:3306/contacts";
    private static final String USERNAME = "contacts";
    private static final String PASSWORD = "contacts";

    public static final String SELECT_SQL = "select customer_id, name, street, city, state, zip, phone, url from customer order by customer_id";
    public static final String INSERT_SQL = "insert into customer(name, street, city, state, zip, phone, url) values(?,?,?,?,?,?,?)";

    public static void main(String[] args)
    {
        Connection connection = null;

        try
        {
            connection = getConnection(URL, USERNAME, PASSWORD);
            List<Map> rows = findAllCustomers(connection);

            for (Map row : rows)
            {
                System.out.println(row);                    
            }
        }
        catch (SQLException e)
        {
            e.printStackTrace();
        }
        finally
        {
            close(connection);
        }
    }

    public static List<Map> findAllCustomers(Connection connection) throws SQLException
    {
        List<Map> rows = new ArrayList<Map>();
        PreparedStatement st = null;
        ResultSet rs = null;

        try
        {
            st = connection.prepareStatement(SELECT_SQL);
            rs = st.executeQuery();
            while (rs.next())
            {
                rows.add(map(rs));                
            }
        }
        finally
        {
            close(rs);
            close(st);
        }

        return rows;
    }

    private static Map<String, Object> map(ResultSet rs) throws SQLException
    {
        Map<String, Object> row = new LinkedHashMap<String, Object>();

        ResultSetMetaData meta = rs.getMetaData();

        int numColumns = meta.getColumnCount();
        for (int i = 1; i <= numColumns; ++i)
        {
            String column = meta.getColumnName(i);
            Object value = rs.getObject(i);
            row.put(column, value);
        }

        return row;
    }

    public static Connection getConnection(String url, String username, String password) throws SQLException
    {
        Driver driver = DriverManager.getDriver(url);

        DriverManager.registerDriver(driver);

        return DriverManager.getConnection(url, username, password);
    }

    public static void close(Connection connection)
    {
        try
        {
            if (connection != null)
            {
                connection.close();
            }
        }
        catch (SQLException e)
        {
            e.printStackTrace();
        }
    }

    public static void close(Statement st)
    {
        try
        {
            if (st != null)
            {
                st.close();
            }
        }
        catch (SQLException e)
        {
            e.printStackTrace();
        }
    }

    public static void close(ResultSet rs)
    {
        try
        {
            if (rs != null)
            {
                rs.close();
            }
        }
        catch (SQLException e)
        {
            e.printStackTrace();
        }
    }

    public void rollback(Connection connection)
    {
        try
        {
            if (connection != null)
            {
                connection.rollback();
            }
        }
        catch (SQLException e)
        {
            e.printStackTrace();
        }
    }
}

Answer 2

            /*
             Connection
             */


            import com.mysql.jdbc.Connection;
            import java.sql.DriverManager;


            public class PersonalConnection {

                private String url = "jdbc:mysql://localhost:3306/";
                private String schema = "database name";
                private String uname = "";
                private String password = "";
                private Connection connection;

                public Connection openConnection() {
                    try {
                        try {
                            DriverManager.registerDriver(new com.mysql.jdbc.Driver());
                        } catch (Exception ex) {
                        }
                        connection = (Connection) DriverManager.getConnection(url + schema, uname, password);
                    } catch (Exception ex) {
                    }
                    return connection;
                }

                public void closeConneciton() {
                    try {
                        connection.close();
                    } catch (Exception ex) {
                    }

                }
            }

        /* Servlet */



          response.setContentType("text/html;charset=UTF-8");
                    PrintWriter out = response.getWriter();
                    DetailsBean db = new DetailsBean();

                    String name = request.getParameter("name");
                    String countryname = request.getParameter("countryname");
                    String statename = request.getParameter("statename");

                    db.setName(name);
                    db.setCountry(countryname);
                    db.setState(statename);

                    DetailsManager dm = new DetailsManager();
                    String result = dm.insertDetailsManager(db);
                    if (result.equals("true")) {
                       /* RequestDispatcher rd = request.getRequestDispatcher("StateDetails.jsp?name=" + db.getName());
                        rd.forward(request, response);*/
                        response.sendRedirect("StateDetails.jsp");
                    } else {
                        out.print(result);
                    }

        /*  DAO */



        /*
         * To change this template, choose Tools | Templates
         * and open the template in the editor.
         */


        import com.mysql.jdbc.Connection;
        import java.sql.PreparedStatement;


        import java.sql.ResultSet;


        public class DetailsDAO {

            private Connection connection;
            private PersonalConnection con;

            public DetailsDAO() {
                con = new PersonalConnection();
            }

            public String insertRecordDAO(DetailsBean db) {

                int rowcount=0;
                try {
                    connection=con.openConnection();
                    String query = "INSERT INTO personal_details(user_name,country_name,state_name) values(?,?,?);";
                    PreparedStatement ps = connection.prepareStatement(query);
                    ps.setString(1, db.getName());
                    ps.setString(2, db.getCountry());
                    ps.setString(3, db.getState());
                    rowcount = ps.executeUpdate();
                    if(rowcount==1)
                    {
                        return "true";
                    }
                    else
                    {
                        return "false";
                    }
                } catch (Exception ex) {
                    return ex+"";

                } finally {
                    con.closeConneciton();
                }
            }

            public ResultSet getGetails() throws Exception
            {
                connection=con.openConnection();
                String query="SELECT * from state_details";
                PreparedStatement ps=connection.prepareStatement(query);
                ResultSet rs=ps.executeQuery();
                return rs;
            }
        }

    /*Manager*/

    /*
     * To change this template, choose Tools | Templates
     * and open the template in the editor.
     */

    import java.util.ArrayList;


    public class DetailsManager {

        DetailsDAO detdao = new DetailsDAO();

        public String insertDetailsManager(DetailsBean db) {
            String rowcount = detdao.insertRecordDAO(db);
            return rowcount;
        }



    }

/*Bean*/


/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */



public class DetailsBean {

    private String name;
    private String country;
    private String state;

    public String getCountry() {
        return country;
    }

    public void setCountry(String country) {
        this.country = country;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }


}

Answer 3

Can mysql accept network connections? When you connect with the "mysql" command line program, you're not doing a network connection, but when you do with JDBC you are making a network connection. Try using "-h localhost" in your mysql command line to see.