Failed sqljdbc4 connection when in executable JAR

Question

I have a GUI application that connects to a SQL Server 2008 database using sqljdbc4.jar. If I run this from the command line it works great.

However, once I wrap it into an executable JAR, I get a "No suitable driver found for jdbc:sqlserver://myServer:1433;databaseName=myDb" error. I know that my Windows system CLASSPATH is ignored once it's in a JAR, but I can't figure out include the sqljdbc4.jar within the executable JAR and get a portable application.

My most recent attempt to fix this is as follows:

My MANIFEST.MF file:

Manifest-Version: 1.0
Class-Path: lib/sqljdbc4.jar
Created-By: 1.7.0_11 (Oracle Corporation)
Main-Class: MyApp

The command I use to compile the JAR:

jar cmf MANIFEST.MF MyApp.jar MyApp.class help.html lib

My directory structure is below. I am running the jar command inside the MyApp directory.

+ MyApp
    + lib
        - sqljdbc.jar
    - help.html
    - MANIFEST.MF
    - MyApp.class
    - MyApp.java

When I create the JAR and run it inside the MyApp directory, it works fine. As soon as I pull it out of the directory, I get the error. How can I make the JAR access the sqljdbc.jar that is available internally?

Thanks in advance.

score 1 · Accepted Answer · answered Jan 24 '13 at 12:55

1

When you have an executable jar MyApp.jar with entry in the manifest.mf:

Class-Path: lib/sqljdbc4.jar

This means that the jar has an external dependency to sqljdbc4.jar in the (relative) folder lib. It is not included in the jar you created! So you need to make sure that there is a lib-folder containing sqljdbc4.jar relative to that jar when you execute it. So the folder structure when executing needs to be;

+ (a folder)
   + lib
      - sqljdbc.jar
   - MyApp.jar

answered Jan 24 '13 at 12:55

Mark Rotteveel

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I did notice that behavior as it runs fine in the folder after it's created. Is there a way to get the JAR to use the internal lib/sqljdbc4.jar file that I have included inside? How can I go about making this easily portable? It seems as soon as you move it, it become rather useless. – Ryan Jan 24 '13 at 21:29
No, because that is not how jars and their classpath are designed. If you want a self-contained jar you would need to create a so-called 'fat jar', which simply means that the entire _content_ of the `sqljdbc.jar` is included in your own `MyApp.jar`. Personally I would not use this solution, because I find it ugly and messy. – Mark Rotteveel Jan 25 '13 at 08:27
Well that's unfortunate. I attempted the 'fat jar' idea, but it didn't work (even when creating using JarSplice). It still throws the error. What is the usual solution to situations like this? Should the program be distributed in a self-extracting EXE so that the MyApp.jar and lib directory get extracted together? – Ryan Jan 28 '13 at 20:03
I never use fat-jars because I don't like it, so I can't comment further on it. And yes, you usually distribute your application either with an installer, self-extracting archive or maybe even Java Webstart which takes care of putting everything in the right place. – Mark Rotteveel Jan 29 '13 at 12:40

Failed sqljdbc4 connection when in executable JAR

1 Answers1