loading mysql connector jar

Newbie & Debugging Questions
#1

Hi, I’m trying to load the mysql connector jar file “on-the-fly” but getting a “no suitable driver” message when I try to get the connection.

I’ve got an applet sitting on my server along with the mysql jar file and when I run the applet from a web page with the jar named as an archive it all works fine. But, to shorten the load time I want to load the mysql jar later in the program while the user is paused reading some instructions. So here’s the code:

URL BURL=getCodeBase();
BURI = BURL.toURI();
URLClassLoader cl = null;
cl = new URLClassLoader(new URL[] {BURI.resolve(“mysql-connector-java-5.1.14-bin.jar”).toURL()});
Class.forName(“com.mysql.jdbc.Driver”, true, cl);
//Class.forName(“com.mysql.jdbc.Driver”, true, cl).newInsance();
//DriverManager.registerDriver(null);
Connection C=null;
C=DriverManager.getConnection(“jdbc:mysql://myserver.com/mydb”,un,pw);

The comment lines are among variations I’ve tried but I keep ending with the same problem when getConnection is called “no suitable driver found”.

Any ideas?

Thanks, Steve

#2

Does “BURI.resolve(“mysql-connector-java-5.1.14-bin.jar”).toURL()” return the correct URL? Try making sure it does.

#3

Hi, yes BURI.resolve(“mysql-connector-java-5.1.14-bin.jar”).toURL() does seem to return the correct name. And applying getName() to
Class.forName(“com.mysql.jdbc.Driver”, true, cl) results in com.mysql.jdbc.Driver which I took to indicate the driver was loaded correctly by forName().

But, still get the error…

???

#4

I ran into this while writing a web application server with JS/Rhino. I wanted to allow applications to load it at runtime if they need to without having to bundle it with the server itself.

I can’t remember the details, but for some reason, mysql connector doesn’t register itself as a candidate for DriverManager. The solution I used was to call connect() on the driver instance directly.

You can see my code for this here: http://code.mattcampbell.net/espresso-mysql/file/tip/mysql.js

#5

Just out of interest, why do you have the MySQL .jar on the client, sounds extremely risky.

#6

Thanks Woogley, I’m connected :slight_smile:

#7

SteveyO erm, no intention to introduce a security risk, just to optimise the downloading so it can take place at a convenient time in the game rather than cause delays on startup if loaded via the html applet archive tag.

How does the what I’m doing differ and make a security risk?

#8

It has more to do with the fact that if you connect to the mysql database directly from the applet (loaded directly or later) everyone will be able to see your mysql username and password. Just make sure you limit the access of the user so he only can select, and that everyone is allowed to see all data that is in the tables where the user has the privilige to select. That should be fine as long as no one comes around and floods your database with requests, but there are many ways to do that :slight_smile:

Mike

#9

The security risks are pretty much described as Mickelukas. I would of thought a better way to do this is to send your db updates via a URLConnection (e.g. in xml/json/string format) and do your db updates on the server side. This way you solve your problem of download size (no need for client mysql jar) and don’t expose your database to the world.

#10

Ah, OK, I see what you mean SteveyO and Mickelukas. I’ll look into URLConnection.

Chrs, Steve.
:slight_smile: