MySQL Connector/J not working when packaged into a jar

[XXXconanXXX]

I'm beginning to detest JARs. The first time I found the need for one I had an incredibly frustrating time getting it to read my main-class; this time however, the program doesn't connect to my MySQL database when I package the whole thing into a JAR.

I'm using the MySQL Connector/J Driver 5.1.16 to connect to my database. Works fine when ran through JCreator (Akin to Eclipse or NetBeans) but not when I package it into a JAR.

The connect function looks like this:

public boolean Connect(JTextArea log) {
		con = null;
		try {
			String url = "jdbc:mysql://localhost:3306/test";
			Class.forName("com.mysql.jdbc.Driver").newInstance();
			con = DriverManager.getConnection(url, "root", "");
			return true;

		} catch(Exception e) {
			log.append("Connection Exception: " + e.getMessage() + "\n");
			return false;
		} finally {
		}
	}

The Class.forName().newInstance() is what's giving me the headache. It doesn't load the driver even when I have the classpath inside the directory when I JAR it. I've searched and searched for an answer, and the closest I got is to using various plugins to explode JARs inside of the top-level JAR, which I have no clue how to do, considering most of the solutions are on completely foreign technologies.

Anyone have an idea? This is my first time using the JDBC API, and from what I gather Class.forName creates a new class of that Driver, so why doesn't it? I put the file it calls for in there, which calls to a super (Guessing it's the driver files installed in my Java folder) and it simply won't work. Any ideas?

Thanks in advance for the help.

 

[phyrex1an]

Better post the exception (including stack trace).
What do you mean by "I have the classpath inside the directory when I JAR it"? You need to put the correct classpath in the jar manifest or specify it on the command line when you run the jar.

 

[XXXconanXXX]

Sorry, all it returns is "com.mysql.jdbc.Driver".

I meant that I put Driver.class inside of the directory I packaged. I would assume that having it installed would suffice but it's not.

The correct classpath for what? The JAR runs fine, but it just won't connect to the MySQL database. Is there something else from Connector/J I need to put in with the top-level JAR?

 

[XXXconanXXX]

Okay, so I've managed to narrow down the issue. I put the driver's accompanying .JAR into the classpath of my program, and now it connects to the Driver just fine. Problem is now, that when I go to run it outside of JCreator, it returns a "Communications Link Failure". The full error message is:

"The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server."

I would do a printStackTrace() but I can't append that to the program's JTextArea and I'm running it outside of an IDE. Is there any way to get a printStackTrace() to output to a string so I can append it to the JTextArea?

What's bamboozled me is that it works just fine in JCreator. Whenever I run it as an applet or as a stand-alone program, it won't connect :/

 

[saw792]

The exception text should appear in the console window. If you are running it by double clicking the jar run it from a command line using 'java -jar JarName'.

 

[XXXconanXXX]

I got it to work. Apparently the Connector/J-bin .JAR is supposed to be in the top-level JAR's classpath, not the Driver.class file.

Thanks for the help guys!