CODEWITHSUNDEEP
javamysqljdbcconnection
BrianZ
BrianZ

Reputation: 35

JDBC Connection issues with MySQL

I've been looking over StackOverflow for the last two days for similar problems and have found many people with the same issue, however, nothing suggested has worked for me so I figured I would post my exact question here in case I'm missing something obvious. I've noticed the connection refused causation, however, I know exactly what my username and password is as well as the dbname, so I know it's not an authentication problem.

After much frustration, I have found a class that simply checks the version of MySQL running on my machine. I am running MySQL using XAMPP as well. However, no matter what I try to do, I get the following error:

Apr 26, 2014 7:29:37 PM Version main
SEVERE: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
    at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1127)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:356)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2502)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2539)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2321)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:832)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:417)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:344)
    at java.sql.DriverManager.getConnection(DriverManager.java:579)
    at java.sql.DriverManager.getConnection(DriverManager.java:221)
    at Version.main(Version.java:23)
Caused by: java.net.ConnectException: Connection refused
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:391)
    at java.net.Socket.connect(Socket.java:579)
    at java.net.Socket.connect(Socket.java:528)
    at java.net.Socket.<init>(Socket.java:425)
    at java.net.Socket.<init>(Socket.java:241)
    at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:258)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:306)
    ... 15 more

And here is my Version class: 

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;

public class Version {

    public static void main(String[] args) {

        Connection con = null;
        Statement st = null;
        ResultSet rs = null;

        String url = "jdbc:mysql://localhost:3306/dbname";
        String user = "username";
        String password = "password";

        try {
            con = DriverManager.getConnection(url, user, password);
            st = con.createStatement();
            rs = st.executeQuery("SELECT VERSION()");

            if (rs.next()) {
                System.out.println(rs.getString(1));
            }

        } catch (SQLException ex) {
            Logger lgr = Logger.getLogger(Version.class.getName());
            lgr.log(Level.SEVERE, ex.getMessage(), ex);

        } finally {
            try {
                if (rs != null) {
                    rs.close();
                }
                if (st != null) {
                    st.close();
                }
                if (con != null) {
                    con.close();
                }

            } catch (SQLException ex) {
                Logger lgr = Logger.getLogger(Version.class.getName());
                lgr.log(Level.WARNING, ex.getMessage(), ex);
            }
        }
    }
}

Upvotes: 0

Views: 1638

Answers (3)

Kevz Macalalag
Kevz Macalalag

Reputation: 3

You missed some code pal! try adding Class.forName(com.mysql.jdbc.Driver); in your try catch block. hope it helps

Upvotes: 0

jesus
jesus

Reputation: 1

On ubuntu i work with MySQL and tried to edit a file with terminal
sudo nano /etc/mysql/my.cnf
find the line that contains:
bind-address
just edit this line
bind-address = 0.0.0.0
save the file and restart mysql with
sudo service mysql restart and try again

it worked for me, good luck!

Upvotes: 0

BrianZ
BrianZ

Reputation: 35

I was able to get this working.

I had to reinstall XAMPP and recreate the Database from scratch from the Exported SQL.

You have no idea how annoyed I was to do this. Lots of wasted time. Thanks for the help.

Upvotes: 1

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