Ant loadproperties failed (bcel error?)

Question

I'm working on a simple build script that should get some constants from a java class file and use them as the version numbers in my file names. I use Eclipse and its own Ant, but put bcel-5.2.jar in my libs folder and into the classpath for the Ant call.

<target name="generate_version" depends="compile">
    <loadproperties srcfile="${dir.dest}/MyVersion.class">
        <classpath>
            <fileset dir="${dir.libs}">
                <include name="**/bcel*.jar"/>
            </fileset>
        </classpath>

        <filterchain>
            <classconstants/>
        </filterchain>
    </loadproperties>
</target>

But unfortunatly the ant task loadproperties fails:

build.xml:46: expected a java resource as source

After that I tried to run Ant from outside Eclipse, using this command line:

set ANT_HOME=C:\Program Files\Java\ant\apache-ant-1.7.1
"%ANT_HOME%\bin\ant.bat"

The result is

Buildfile: build.xml

init:
     [echo] Building project.
     [echo] ant.home:          C:\Program Files\Java\ant\apache-ant-1.7.1
     [echo] ant.java.version:  1.6
     [echo] ant.version:       Apache Ant version 1.7.1 compiled on June 27 2008

compile:
    [javac] Compiling 262 source files to **********\build
    [javac] Note: Some input files use or override a deprecated API.
    [javac] Note: Recompile with -Xlint:deprecation for details.
    [javac] Note: Some input files use unchecked or unsafe operations.
    [javac] Note: Recompile with -Xlint:unchecked for details.

generate_version:

BUILD FAILED
********************\ant\build.xml:46: expected a java resource as source

I'm really lost now. Is it a bcel error? Is it an Ant incompatibility with my own bcel?

One last hint: Removing the bcel classpath entry from the Ant target results in this:

Buildfile: build.xml

init:
     [echo] Building project.
     [echo] ant.home:          C:\Program Files\Java\ant\apache-ant-1.7.1
     [echo] ant.java.version:  1.6
     [echo] ant.version:       Apache Ant version 1.7.1 compiled on June 27 2008

compile:
    [javac] Compiling 262 source files to ********************\build
    [javac] Note: Some input files use or override a deprecated API.
    [javac] Note: Recompile with -Xlint:deprecation for details.
    [javac] Note: Some input files use unchecked or unsafe operations.
    [javac] Note: Recompile with -Xlint:unchecked for details.

generate_version:

BUILD FAILED
java.lang.NoClassDefFoundError: org/apache/bcel/classfile/ClassParser
        at org.apache.tools.ant.filters.util.JavaClassHelper.getConstants(JavaClassHelper.java:47)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

UPDATE After setting the Ant preferences in Eclipse, the error message changed:

BUILD FAILED
*********************\build.xml:46: org.apache.bcel.classfile.ClassFormatException:  is not a Java .class file
    at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:115)
    at org.apache.tools.ant.Task.perform(Task.java:348)
    at org.apache.tools.ant.Target.execute(Target.java:357)
    at org.apache.tools.ant.Target.performTasks(Target.java:385)
    at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1329)
    at org.apache.tools.ant.Project.executeTarget(Project.java:1298)
    at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
    at org.eclipse.ant.internal.ui.antsupport.EclipseDefaultExecutor.executeTargets(EclipseDefaultExecutor.java:32)
    at org.apache.tools.ant.Project.executeTargets(Project.java:1181)
    at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.run(InternalAntRunner.java:423)
    at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.main(InternalAntRunner.java:137)

Now I think it's maybe a version conflict between Ant and BCEL. Or BCEL and JDK1.6. Or Eclipse and BCEL and Ant or JDK... I'm lost.

---

ANSWER:

This is the comment found below

I should have mentioned this - you do not need to convert anything. Doc: "since Ant 1.7, the character encoding ISO-8859-1 is used to convert from characters back to bytes, so ONE HAS TO USE THIS ENCODING for reading the java class file." This is just a convention to get round the fact that a character filter is being used on raw bytes. ant.apache.org/manual/CoreTypes/… Using UTF-8 would be bad! – McDowell

Necktie

I think this will come down to some compatibility problems with BCEL and the JDK. "is not a Java .class file" points to a mismatching class version (first 4 bytes in .class) that is not recognized by BCEL. I try to compile with JDK1.4 again. – Necktie

Answer 1

Crap, I knew it! It comes down to file encoding issues. The files are still in ISO-8819-1, but I'm using UTF-8. The project is pretty aged and was created with the wrong encoding in place. Setting the parameter encoding in the javac and loadproperties Task fixes it.

<target name="generate_version" depends="compile">
    <loadproperties encoding="iso-8859-1" srcfile="${dir.dest}/MyVersion.class">
        <filterchain>
            <classconstants/>
        </filterchain>
    </loadproperties>
</target>

I thought it got changed by our Subversion server, but I think I have to convert every single file to UTF-8 myself now... think that is another question for SO.

Necktie

I should have mentioned this - you do not need to convert anything. Doc: "since Ant 1.7, the character encoding ISO-8859-1 is used to convert from characters back to bytes, so ONE HAS TO USE THIS ENCODING for reading the java class file." This is just a convention to get round the fact that a character filter is being used on raw bytes. ant.apache.org/manual/CoreTypes/filterchain.html Using UTF-8 would be bad! – Catfish

Hm, I'm not 100% sure if I get it right. I will re-run the build with the converted files and the original ones and apply/remove the encoding parameter to get an answer. But I'll commit the converted files first... ;-) – Necktie

Ok, really the only flaw was the missing parameter encoding="iso-8859-1". Thanks @McDowell! I guess I should've RTFM the whole filterchain. :-( – Necktie

The link to filterchain has moved to: ant.apache.org/manual/Types/filterchain.html – Mcpherson

Answer 2

The documentation for loadproperties says that the nested classpath element is for use with the resource attribute - an alternative to using srcfile.

Add the BCEL jar to your global classpath. In Eclipse, add it as a global entry to your classpath in the runtime preferences. On the command line, use the -lib switch.

_{(source: eclipse.org)}

Catfish

Ah, that helped - at least for some seconds. I updated the question. – Necktie

Answer 3

Looks like a classpath error. Run "ant -v" to give you some more detail on errors.

Magdala