No suitable driver found when including the needed drivers with maven-assembly-plugin [duplicate]

Question

Possible Duplicate:
java error (No suitable driver found)

I have a very small too that works with a PostgreSQL DB and it would be very convenient to use it as a single jar. So indeed I've tried using the maven-assembly-plugin like so:

<artifactId>maven-assembly-plugin</artifactId>
                <version>2.3</version>
                <configuration>
                    <archive>
                        <manifest>
                            <mainClass>pack.name.MainClass</mainClass>
                        </manifest>
                    </archive>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                </configuration>

And it works perfectly fine, I can see all the files I require added to the jar file, including the driver's files but when I'm trying to run it I get a:

java.sql.SQLException: No suitable driver found for jdbc:postgresql://<ip>:5432/dbname

I have this:

<dependencies>
        <dependency>
            <groupId>com.oracle</groupId>
            <artifactId>ojdbc6</artifactId>
            <version>11.2.0.3</version>
        </dependency> 
        <dependency>
            <groupId>postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>9.1-901-1.jdbc4</version>
        </dependency>

In the dependencies and the URL is exactly as I wrote above (except the censored address :) ). What am I missing?

Thanks!

Answer 1

If you don't use Class.forName(...) to load the driver manually, then I think you faced an infamous problem with maven-assembly-plugin - it overwrites files with the same name when they come from different jars.

In your case JDBC driver discovery mechanism relies on a file named /META-INF/services/java.sql.Driver, and you have at least two jars containing such a file in your dependencies (Oracle and Postgres drivers), therefore one of them is lost after running maven-assembly-plugin.

You can use maven-shade-plugin instead of maven-assembly-plugin to merge these files correcly, as described here.

Alternatively, you can use Class.forName(...) to sidestep the failing autodiscovery mechanism.