patch for GeneralLegacyIndexCodes.loadCodes

[Mihail Andreev]

Hello and thank you for such great Java module!

I have small patch to suggest.
---------------------->>>
===================================================================
--- src/com/healthmarketscience/jackcess/GeneralLegacyIndexCodes.java
+++ src/com/healthmarketscience/jackcess/GeneralLegacyIndexCodes.java
@@ -326,7 +326,7 @@

reader = new BufferedReader(
new InputStreamReader(
- Thread.currentThread().getContextClassLoader()
+ GeneralLegacyIndexCodes.class.getClassLoader()
.getResourceAsStream(codesFilePath), "US-ASCII"));

int start = asUnsignedChar(firstChar);
<<< -------------------------------------

Some comments. My setup includes application server, application which has
Java API to develop custom blocks so it can be deploy into the application as
jar file (or set of jar files).
Application server and application both are not open source and not all
details of the deployment process are documented, but it looks like class
loader of the current thread and the Jackcess library class loader are not the
same.
and as the code is called in a static initialization my function throws
java.lang.ExceptionInInitializerError at run time

The stack trace goes like that:

java.lang.ExceptionInInitializerError
at com.healthmarketscience.jackcess.GeneralLegacyIndexCodes.getCharHandler(Gen
eralLegacyIndexCodes.java:302)
at com.healthmarketscience.jackcess.GeneralLegacyIndexCodes.writeNonNullIndexT
extValue(GeneralLegacyIndexCodes.java:514)
at com.healthmarketscience.jackcess.IndexData$GenLegTextColumnDescriptor.write
NonNullValue(IndexData.java:1547)
at com.healthmarketscience.jackcess.IndexData$ColumnDescriptor.writeValue(Inde
xData.java:1311)
<...skiped...>
Caused by: java.lang.NullPointerException
at java.io.Reader.<init>(Reader.java:61)
at java.io.InputStreamReader.<init>(InputStreamReader.java:80)
at com.healthmarketscience.jackcess.GeneralLegacyIndexCodes.loadCodes(GeneralL
egacyIndexCodes.java:327)
at com.healthmarketscience.jackcess.GeneralLegacyIndexCodes$Codes.<clinit&g
t;(GeneralLegacyIndexCodes.java:278)
... 92 more

I recompiled Jackcess 1.2.4 with this one-line patch and the problem is gone.

Mike

[Alejandro Domínguez]

Do you resolve it?

[James Ahlborn]

just curious. can you create new databases without a problem? the reason i ask
is because the database creation code uses the same call
"Thread.currentThread().getContextClassLoader().getResourceAsStream()".

[James Ahlborn]

FYI, i've checked in changes which will be in the 1.2.5 release which will try
both the class's classloader and the Thread context classloader.

[Mihail Andreev]

for my task I only need to read MS Access file.
so I didn't try the creation code though I saw the same
Thread.currentThread().getContextClassLoader() call in this place.
actually I'm quite sure that the result will be the same exception.
do you want me to try it in my environment?

[Mihail Andreev]

Thank you for the update!

but I'm just wondering is it really make sense to try Thread context
classloader? as I see it the class's classloader must have the resource.

[James Ahlborn]

Sometimes app servers do weird things with classloaders (that's why i was
using the context classloader). i expect that most lookups should work with
the class classloader, but, just to be safe, i left the old code there as well
as a backstop.

[MeW]

This issue resurfaces in the latest build 2.0.4. The code has moved somehwat into DatabaseImpl.java. I've patched the getResourceAsStream to prevent a nil pointer exception:

/**
 * When used in a jar, the getClassLoader may return null.
 * Make sure to check this before calling methods.
 */

static InputStream getResourceAsStream(String resourceName)
throws IOException
{
InputStream stream = null;

if (DatabaseImpl.class.getClassLoader() != null) {
    stream = DatabaseImpl.class.getClassLoader()
            .getResourceAsStream(resourceName);
}

if(stream == null) {

    stream = Thread.currentThread().getContextClassLoader()
    .getResourceAsStream(resourceName);

    if(stream == null) {
    throw new IOException("Could not load jackcess resource " +
                          resourceName);
  }

}

return stream;

}

[James Ahlborn]

You have a situation where the classloader for the DatabaseImpl class is null? That doesn't seem possible. as far as i understand, that can only return null for system classes.