ThreadLocal is your answer.
Here's what I did. I made a class called "ModelOperation.java" that holds the who, what, why, with what being an enum. Making a new one of these objects push itself into a ThreadLocal while remembering any previous value. Calling .pop on the model operation puts the previous value back (which will be null). In other words there's a stack of pending ModelOperations that hold the data:
ModelOperation mo = new ModelOperation(what, who, why);
// do stuff
mo.pop().
If there isn't a current ModelOperation object, I throw in the Listener, which forces all the code that commits to the database to have an audit trail setup. So you need to do auditing early in development, not later.
Pierce
P.S.
There's one issue with Envers that's kind of a pain, which is that it's kind of hard to set all that up with EJBs, which was why I was searching to see if someone had a better solution. I've ended up having to refactor things to wrap all EJB calls that require a transaction with the above code by having a wrapper EJB that calls the other EJB. Of course, its not too bad, because I need that for optimistic locking failure checks anyways, but it seems to be kind of a hole in the whole EJB spec that you can wrap an invocation, but you can't wrap the transaction commit.
Anyone have a better way of solving that problem? That is, wrapping the execution of the EJB method including the transaction stuff instead of inside the transaction stuff?
/**
* Class to hold the current operation being performed on the model for Auditing purposes.
*
* @author pierce
*/
public class ModelOperation
{
//~ Static fields/initializers -----------------------------------------------------------------
/** DOCUMENT ME! */
private static final ThreadLocal<ModelOperation> currentOperation =
new ThreadLocal<ModelOperation>();
//~ Instance fields ----------------------------------------------------------------------------
/** DOCUMENT ME! */
public ModelOperationType operationType;
/** DOCUMENT ME! */
public String who;
/** DOCUMENT ME! */
public String why;
/** DOCUMENT ME! */
public ModelOperation previous;
//~ Constructors -------------------------------------------------------------------------------
/**
* Creates a new ModelOperation object.
*
* @param operationType DOCUMENT ME!
* @param who DOCUMENT ME!
* @param why DOCUMENT ME!
*/
public ModelOperation(ModelOperationType operationType, String who, String why)
{
super();
this.operationType = operationType;
this.who = who;
this.why = why;
push();
}
//~ Methods ------------------------------------------------------------------------------------
/**
* DOCUMENT ME!
*/
public void push()
{
previous = currentOperation.get();
currentOperation.set(this);
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public ModelOperation pop()
{
currentOperation.set(previous);
previous = null;
return currentOperation.get();
}
/**
* DOCUMENT ME!
*/
public static void popAll()
{
while (currentOperation.get() != null)
{
currentOperation.get().pop();
}
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public static ModelOperation current()
{
return currentOperation.get();
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public ModelOperationType getOperationType()
{
return this.operationType;
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public String getWho()
{
return who;
}
/**
* DOCUMENT ME!
*
* @param who DOCUMENT ME!
*/
public void setWho(String who)
{
this.who = who;
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public String getWhy()
{
return why;
}
/**
* DOCUMENT ME!
*
* @param why DOCUMENT ME!
*/
public void setWhy(String why)
{
this.why = why;
}
/**
* DOCUMENT ME!
*
* @param operationType DOCUMENT ME!
*/
public void setOperationType(ModelOperationType operationType)
{
this.operationType = operationType;
}
} // end class ModelOperation
/**
* Class to hold the current operation being performed on the model for Auditing purposes.
*
* @author pierce
*/
public class ModelOperation
{
//~ Static fields/initializers -----------------------------------------------------------------
/** DOCUMENT ME! */
private static final ThreadLocal<ModelOperation> currentOperation =
new ThreadLocal<ModelOperation>();
//~ Instance fields ----------------------------------------------------------------------------
/** DOCUMENT ME! */
public ModelOperationType operationType;
/** DOCUMENT ME! */
public String who;
/** DOCUMENT ME! */
public String why;
/** DOCUMENT ME! */
public ModelOperation previous;
//~ Constructors -------------------------------------------------------------------------------
/**
* Creates a new ModelOperation object.
*
* @param operationType DOCUMENT ME!
* @param who DOCUMENT ME!
* @param why DOCUMENT ME!
*/
public ModelOperation(ModelOperationType operationType, String who, String why)
{
super();
this.operationType = operationType;
this.who = who;
this.why = why;
push();
}
//~ Methods ------------------------------------------------------------------------------------
/**
* DOCUMENT ME!
*/
public void push()
{
previous = currentOperation.get();
currentOperation.set(this);
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public ModelOperation pop()
{
currentOperation.set(previous);
previous = null;
return currentOperation.get();
}
/**
* DOCUMENT ME!
*/
public static void popAll()
{
while (currentOperation.get() != null)
{
currentOperation.get().pop();
}
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public static ModelOperation current()
{
return currentOperation.get();
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public ModelOperationType getOperationType()
{
return this.operationType;
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public String getWho()
{
return who;
}
/**
* DOCUMENT ME!
*
* @param who DOCUMENT ME!
*/
public void setWho(String who)
{
this.who = who;
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public String getWhy()
{
return why;
}
/**
* DOCUMENT ME!
*
* @param why DOCUMENT ME!
*/
public void setWhy(String why)
{
this.why = why;
}
/**
* DOCUMENT ME!
*
* @param operationType DOCUMENT ME!
*/
public void setOperationType(ModelOperationType operationType)
{
this.operationType = operationType;
}
} // end class ModelOperation
/**
* Class to hold the current operation being performed on the model for Auditing purposes.
*
* @author pierce
*/
public class ModelOperation
{
//~ Static fields/initializers -----------------------------------------------------------------
/** DOCUMENT ME! */
private static final ThreadLocal<ModelOperation> currentOperation =
new ThreadLocal<ModelOperation>();
//~ Instance fields ----------------------------------------------------------------------------
/** DOCUMENT ME! */
public ModelOperationType operationType;
/** DOCUMENT ME! */
public String who;
/** DOCUMENT ME! */
public String why;
/** DOCUMENT ME! */
public ModelOperation previous;
//~ Constructors -------------------------------------------------------------------------------
/**
* Creates a new ModelOperation object.
*
* @param operationType DOCUMENT ME!
* @param who DOCUMENT ME!
* @param why DOCUMENT ME!
*/
public ModelOperation(ModelOperationType operationType, String who, String why)
{
super();
this.operationType = operationType;
this.who = who;
this.why = why;
push();
}
//~ Methods ------------------------------------------------------------------------------------
/**
* DOCUMENT ME!
*/
public void push()
{
previous = currentOperation.get();
currentOperation.set(this);
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public ModelOperation pop()
{
currentOperation.set(previous);
previous = null;
return currentOperation.get();
}
/**
* DOCUMENT ME!
*/
public static void popAll()
{
while (currentOperation.get() != null)
{
currentOperation.get().pop();
}
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public static ModelOperation current()
{
return currentOperation.get();
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public ModelOperationType getOperationType()
{
return this.operationType;
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public String getWho()
{
return who;
}
/**
* DOCUMENT ME!
*
* @param who DOCUMENT ME!
*/
public void setWho(String who)
{
this.who = who;
}
/**
* DOCUMENT ME!
*
* @return DOCUMENT ME!
*/
public String getWhy()
{
return why;
}
/**
* DOCUMENT ME!
*
* @param why DOCUMENT ME!
*/
public void setWhy(String why)
{
this.why = why;
}
/**
* DOCUMENT ME!
*
* @param operationType DOCUMENT ME!
*/
public void setOperationType(ModelOperationType operationType)
{
this.operationType = operationType;
}
} // end class ModelOperation
