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From Michael Carman <michael.j.car...@gmail.com>
Subject Re: ClassNotFoundException trying to use JDBC appender
Date Tue, 29 Nov 2016 22:08:13 GMT
To try to tease out whether my problem is at the Eclipse level or the Log4j
level I experimented with loading my class via reflection.

static {
try {
Class<?>   clazz      = Class.forName("x.y.z.LogDB");
Method     method     = clazz.getMethod("getConnection");
Connection connection = (Connection) method.invoke(clazz);
connection.close();
} catch (Exception e) {
e.printStackTrace();
}
logger = LogManager.getLogger();
}

My attempt at reflection is successful. The call to LogManager.getLogger()
results in a ClassNotFoundException. This implies that my problem is that
Log4j isn't picking up on the class path used within my plugin. Is there a
way to configure that? Searching for "log4j classpath" turns up lots of
things about where to put the log4j.properties file.

I can't be the first person to try to use a JDBC appender with Eclipse RCP.

-Mike


On Tue, Nov 29, 2016 at 3:27 PM Michael Carman <michael.j.carman@gmail.com>
wrote:

> Yes, getConnection() is static. Log4j isn't getting far enough to attempt
> calling it, though. An explicit call to LogDB.getConnection()  is
> successful but Log4j's attempts to invoke it via reflection fails trying to
> load the class. That holds true even if I move my LogDB into the plug-in
> for my application and pre-load it! e.g., in the Activator for my main
> plug-in:
>
> static {
> try {
> LogDB.getConnection(); // succeeds
> } catch (SQLException e) {
> e.printStackTrace();
> }
> LogManager.getLogger(); // throws ClassNotFoundException
> }
>
> It seems like some sort of class path configuration problem, but I can't
> figure out what to set.
>
> -Mike
>
> On Tue, Nov 29, 2016 at 2:43 PM Gary Gregory <garydgregory@gmail.com>
> wrote:
>
> Is your getConnection() method static?
>
> Gary
>
> On Tue, Nov 29, 2016 at 9:04 AM, Michael Carman <
> michael.j.carman@gmail.com>
> wrote:
>
> > I'm using Log4j2 in an Eclipse RCP application. I've been using a
> > RollingFileAppender and am trying to switch to a JDBC appender backed by
> a
> > ConnectionFactory. I've implemented this using the examples at
> > https://logging.apache.org/log4j/2.x/manual/appenders.html#JDBCAppender
> as
> > a guide but get a ClassNotFoundException at each call to
> > LogManager.getLogger(). e.g.
> >
> > 2016-11-29 10:23:06,233 main ERROR java.lang.ClassNotFoundException:
> > x.y.z.LogDB java.lang.ClassNotFoundException: x.y.z.LogDB
> >     at
> > org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(
> > BundleLoader.java:506)
> >     at
> > org.eclipse.osgi.internal.loader.BundleLoader.findClass(
> > BundleLoader.java:422)
> >     at
> > org.eclipse.osgi.internal.loader.BundleLoader.findClass(
> > BundleLoader.java:410)
> >     at
> > org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(
> > DefaultClassLoader.java:107)
> >     at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
> >     at java.lang.Class.forName0(Native Method)
> >     at java.lang.Class.forName(Class.java:264)
> >     at
> > org.apache.logging.log4j.util.LoaderUtil.loadClass(LoaderUtil.java:141)
> >     at
> > org.apache.logging.log4j.core.appender.db.jdbc.
> > FactoryMethodConnectionSource.createConnectionSource(
> > FactoryMethodConnectionSource.java:82)
> >     ...
> >
> > My log4j2.xml defines the appender as:
> >
> > <JDBC name="DB" tableName="APP_LOG">
> >   <ConnectionFactory class="x.y.z.LogDB" method="getConnection" />
> >   <Column name="TIMESTAMP" isEventTimestamp="true"    />
> >   <Column name="PID"       pattern="%X{pid}"          />
> >   <Column name="THREAD"    pattern="%thread"          />
> >   <Column name="USERNAME"  pattern="${env:USERNAME}"  />
> >   <Column name="SEVERITY"  pattern="%level"           />
> >   <Column name="LOGGER"    pattern="%logger{1.1.1.*}" />
> >   <Column name="MESSAGE"   pattern="%message"         />
> >   <Column name="EXCEPTION" pattern="%exception" isClob="true" />
> > </JDBC>
> >
> > I've looked at the obvious things: the name of my factory class matches
> > between my code and config file, it's declared public, and its package is
> > exported by the parent plug-in. (The parent plug-in is also required by
> > other plugins via their manifests.) I can't see why the class loader
> > shouldn't be able to find it. I assume there's something simple and
> stupid
> > that I'm missing.
> >
> > I'm using Eclipse 3.6.2 (Helios) and Log4j 2.7.
> >
> > -Mike
> >
>
>
>
> --
> E-Mail: garydgregory@gmail.com | ggregory@apache.org
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