public TransactionLocal() 
{
                     
      try
      {
         InitialContext context = new InitialContext();
         transactionManager = (TransactionManager) context.lookup("java:/TransactionManager");
      }
      catch(NamingException e)
      {
         throw new IllegalStateException(
            "An error occured while looking up the transaction manager: " + e
         );
      }
      initDelegate();
}

Creates a thread local variable.

Throws:

IllegalStateException - if there is no system transaction manager

 public TransactionLocal(TransactionManager tm) 
{
      if (tm == null)
         throw new IllegalArgumentException("Null transaction manager");
      this.transactionManager = tm;
      initDelegate();
}

Creates a thread local variable. Using the given transaction manager

Parameters:

tm - the transaction manager

 protected boolean containsValue(Transaction tx) 
{
      return delegate.containsValue(this, tx);
}

does Transaction contain object?

 public Object get() 
{
      return get(getTransaction());
}

Returns the value of this TransactionLocal variable associated with the thread context transaction. Creates and initializes the copy if this is the first time the method is called in a transaction.

 public Object get(Transaction transaction) 
{
      if (transaction == null) return initialValue();
      Object value = getValue(transaction);
      // is we didn't get a value initalize this object with initialValue()
      if(value == null)
      {
         // get the initial value
         value = initialValue();
         // if value is null replace it with the null value standin
         if(value == null)
         {
            value = NULL_VALUE;
         }
         // store the value
         storeValue(transaction, value);
      }
      // if the value is the null standin return null
      if(value == NULL_VALUE)
      {
         return null;
      }
      // finall return the value
      return value;
}

Returns the value of this TransactionLocal variable associated with the specified transaction. Creates and initializes the copy if this is the first time the method is called in a transaction.

 protected Transaction getTransaction() 
{
      try
      {
         return transactionManager.getTransaction();
      }
      catch(SystemException e)
      {
         throw new IllegalStateException("An error occured while getting the " +
               "transaction associated with the current thread: " + e);
      }
}

 protected Object getValue(Transaction tx) 
{
      return delegate.getValue(this, tx);
}

get the transaction local value.

 protected  void initDelegate() 
{
      if (transactionManager instanceof TransactionLocalDelegate)
         delegate = (TransactionLocalDelegate) transactionManager;
      else
         delegate = new TransactionLocalDelegateImpl(transactionManager);
}

Initialise the delegate

 protected Object initialValue() 
{
      return null;
}

Returns the initial value for this thransaction local. This method will be called once per accessing transaction for each TransactionLocal, the first time each transaction accesses the variable with get or set. If the programmer desires TransactionLocal variables to be initialized to some value other than null, TransactionLocal must be subclassed, and this method overridden. Typically, an anonymous inner class will be used. Typical implementations of initialValue will call an appropriate constructor and return the newly constructed object.

 public  void set(Object value) 
{
      set(getTransaction(), value);
}

Sets the value of this TransactionLocal variable associtated with the thread context transaction. This is only used to change the value from the one assigned by the initialValue method, and many applications will have no need for this functionality.

 public  void set(Transaction transaction,
    Object value) 
{
      if (transaction == null) throw new IllegalStateException("there is no transaction");
      // If this transaction is unknown, register for synchroniztion callback,
      // and call initialValue to give subclasses a chance to do some 
      // initialization.
      if(!containsValue(transaction))
      {
         initialValue();
      }
      // if value is null replace it with the null value standin
      if(value == null)
      {
         value = NULL_VALUE;
      }
      // finally store the value
      storeValue(transaction, value);
}

Sets the value of this TransactionLocal variable associtated with the specified transaction. This is only used to change the value from the one assigned by the initialValue method, and many applications will have no need for this functionality.

 protected  void storeValue(Transaction tx,
    Object value) 
{
   
      delegate.storeValue(this, tx, value);
}

put the value in the TransactionImpl map