JAVA custom Annotation & Concurrent Versions System

I manage my sources using CVS (Concurrent Versions System). When a user reported a bug in one of my java program, I faced the problem to get the version of the java class where the Exception was throwed..... I don't know if this was described but here is my solution using a custom java annotation. CVS can use a mechanism known as keyword substitution (or keyword expansion) to help identifying the files. Embedded strings of the form $keyword$ and $keyword:…$ in a file are replaced with strings of the form $keyword:value$ whenever you obtain a new revision of the file. Here I used Date,Source and Revision.

First I defined a new custom Annotation called @RCS returning the author, a date and a revision.

import java.lang.annotation.*;
/**
 * describe a Revision Control System
 * @author pierre
 *
 */
@Retention(RetentionPolicy.RUNTIME) /* The annotation should be available for reflection at runtime.*/
@Target(ElementType.TYPE) /* place in : class, interface, enum */
public @interface RCS {
        /** author of this source */
         String author() default '[undefined]';
         /** revision number of this source */
         String revision() default '[undefined]';
         /** date of revision of this source */
         String date()   default '[undefined]';
         /** file name for this source */
         String source()   default '[undefined]';
}

and here are two files used for test. Both classes contains a @RCS annotation which can be find at runtime. Test2 jsut throws an Exception. Test1 catch this exception and display the stack trace. for each StackTraceElement it tries to find a @RCS annotation.

import java.lang.annotation.*;
@RCS(   author='$Author: $',
                date='$Date: $',
                source='$Source: $',
                revision='$Revision: $'
                )
public class Test
{

Test()
        {
        Test2 t=new Test2();
        t.doSomething();
        }



public static void main(String args[])
        {
        try
                {
                Test t= new Test();
                }
        catch(Exception err)
                {

                System.err.println(err.getLocalizedMessage());
                for(StackTraceElement e: err.getStackTrace())
                        {
                        System.err.println('Class :\t\t\t'+e. getClassName());
                        System.err.println('File :\t\t\t'+e.  getFileName());
                        System.err.println('Line :\t\t\t'+e.  getLineNumber());

                        if(e.getClassName()!=null)
                        {
                        try {
                             Class c= Class.forName( e.getClassName());
                             RCS rcsInfo=(RCS)c.getAnnotation(RCS.class);
                             System.err.println('Revision:\t\t'+(rcsInfo==null?'N/A':rcsInfo.revision()));
                             System.err.println('Date:\t\t\t'+(rcsInfo==null?'N/A':rcsInfo.date()));
                             System.err.println('Author:\t\t\t'+(rcsInfo==null?'N/A':rcsInfo.author()));
                             }
                        catch (Exception err2)
                                {
                                }
                        }
                        System.err.println();
                        }
                }

        }
}

@RCS(   author='$Author:  $',
                date='$Date: $',
                source='$Source: $',
                revision='$Revision: $'
                )
public class Test2
{
Test2()
        {
        }
void doSomething()
        {
        throw new RuntimeException('Test');
        }

}

when the files where committed the CVS fields were substituted by their correct values. Here is the stack trace as it was printed:

pierre@linux:~/tmp/src> cvs commit
(...)
pierre@linux:~/tmp/src> javac Test.java
pierre@linux:~/tmp/src> java Test
Test
Class :                 Test2
File :                  Test2.java
Line :                  13
Revision:               $Revision: 1.2 $
Date:                   $Date: 2006/10/31 18:10:44 $
Author:                 $Author: pierre $

Class :                 Test
File :                  Test.java
Line :                  15
Revision:               $Revision: 1.5 $
Date:                   $Date: 2006/10/31 18:54:08 $
Author:                 $Author: pierre $

Class :                 Test
File :                  Test.java
Line :                  24
Revision:               $Revision: 1.5 $
Date:                   $Date: 2006/10/31 18:54:08 $
Author:                 $Author: pierre $

That's it.
Pierre

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