Add the changing message in your java code

When you are developing a java project,you maybe want to log the history of the reason of changing your java code.You can write some comment on the head of a java file,but if there are too many files you changed which have the same reason,you need write the same comment in every java file.It's very terror.But if you use cvs to manage your source codes,you can write a line of comment like this:
$Log: ClassName,v $
then,when you commit the source you changed,you can write some message to explain what you did.