connect java to mysql using jdbc on osx

Question

So I added the MySQL Connector/J 5.1.16 to my project's Build Path. I'm using the default OSX Java package and MAMP Pro 1.9.4 with MySQL 5.1.44 and Eclipse.

I've set up a simple java app with the following function:

private static String dbUrl = "jdbc:mysql://127.0.0.1:3306/mpp";
private static String dbUsername = "root";
private static String dbPassword = "root";

private Statement statement = null;

private void dbConnect() {


try {
    Class.forName("com.mysql.jdbc.Driver");
    Connection connection = DriverManager.getConnection(dbUrl, dbUsername, dbPassword);
    statement = connection.createStatement();

} catch(SQLException e) {
    System.err.print(e.getMessage() + " ARGH!");
} catch(Exception e) {
    System.err.print(e.getMessage() + " FUUUUUUUUUU!");
}
}

When I run it I get the following error:

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. ARGH!

I googled and searched for about an hour with no success. Any ideas on how to fix this? The JDBC driver should be fine, I kinda tested it.

EDIT

I tried running this through the console

SnowCave:src stefanschipor$ java -cp $CLASSPATH test

I get the same output as above

Answer 1

OK, this is just silly. :)

You have open up MAMP, go to Server > MySQL and uncheck "Allow local access only" which is checked by default. This is weird since what I'm doing is local, but anyways...

My program seems to work and the commands suggested by @JamesA also yield the expected output!

Huzzah!

Answer 2

Are you sure MySQL is running on port 3306?

---

If the mysql daemon is listening on port 3306 lsof -i:3306 should return:

COMMAND  PID        USER   FD   TYPE     DEVICE SIZE/OFF NODE NAME
mysqld  7616    username   10u  IPv6 0x1fbf6940      0t0  TCP *:mysql (LISTEN)

---

A direct connect to the port using nc localhost 3306 should return:

H
5.5.969]G.Mw4??9cfUY?k!^:D&mysql_native_password

where 5.5.969 is the mysql version number.

---

You could also try a tool like DbVisualizer to test your connection URL.

Answer 3

you need to use the Port localhost:8889 or whatever port you find in MAMP > Settings > Ports > MySQL-Port. Then your Connection will succeed!

Answer 4

Its just because your mysql service is not running... just run the mysql service from system preferences or if you have installed it using brew run brew services start mysql

Answer 5

I also have this mysterious error on OSX and didn't found any solution the first time the error occurred. In my cases it occurs if the database structure was modified or tables were dropped/created during development (MySQL as a Datasource for JBoss). In all cases I can avoid the error if I shut down MySQL after modifications and restart it before JBoss starts.