Hi there,
tried to find this information on the Internet, but also in the derby wiki, but
was not successful
so far, hence posting this question here where hopefully those in the know can
help out.
Using derby from Oracle's JDK 7 distribution I encountered a problem and after
a loong time of
research, testing, trials and errors I came up with a solution, but still do
not understand the
reason for the problem!
Here is the problem:
* having a class from a jar that is placed in one of the java.ext.dirs
loading the derby JDBC (to
be precise: 'org.apache.derby.jdbc.EmbeddedDriver' and then issuing a
newInstance()) from the
classpath works, but the subsequent
java.sql.DriverManager.getConnection('jdbc:derby:derbyDB;create=true',props)
where 'props' is a
java.util.Properties with "user1/user1" and "password/user1", yields:
getCause(): [java.sql.SQLException: No suitable driver found for
jdbc:derby:derbyDB;create=true]
The same program works without any changes,
* if the jar-file loading the derby JDBC is not in java.ext.dirs but on the
classpath then it works
* if the jar-file and derby.jar are both in java.ext.dirs then it works
My question is, why is this so?
(It seems to be the case that both, the Java class that loads the derby JDBC
driver and the derby
JDBC driver, must use the same class loader, either a
sun.misc.Launcher$AppClassLoader or a
sun.misc.Launcher$ExtClassLoader, which is very strange as I have not
encountered a similar
requirement/behaviour in any other use case in the past years. The thread
context class loader is
the application class loader which, if used, would have found derby.jar given
on the classpath.)
Is there any documentation that leads to an explanation about this behaviour
somewhere? Are there
other Java infrastructures that have such a restriction that anyone is aware of?
---
Background: I am authoring a scripting language binding for Java (BSF4ooRexx)
and moving the
BSF4ooRexx jar to a Java extension directory makes it available to all Java
applications including
the JavaPlugins for browsers. All test and sample programs work in this setup,
except for the sample
program that demonstrates how easy it is to use derby via JDBC! :(
---
Thankful for any pointer, hints, links, explanations that shed some light into
this corner!
---rony
