ejbLoad and ejbStore Methods

If the EJB container needs to synchronize the instance variables of an entity bean with the corresponding values stored in a database, it invokes the ejbLoad and ejbStore methods. TheejbLoad method refreshes the instance variables from the database, and the ejbStore method writes the variables to the database. The client may not call ejbLoad and ejbStore.

If a business method is associated with a transaction, the container invokes ejbLoad before the business method executes. Immediately after the business method executes, the container callsejbStore. Because the container invokes ejbLoad and ejbStore, you do not have to refresh and store the instance variables in your business methods. The SavingsAccountBean class relies on the container to synchronize the instance variables with the database. Therefore, the business methods of SavingsAccountBean should be associated with transactions.

If the ejbLoad and ejbStore methods cannot locate an entity in the underlying database, they should throw the javax.ejb.NoSuchEntityException. This exception is a subclass ofEJBException. Because EJBException is a subclass of RuntimeException, you do not have to include it in the throws clause. When NoSuchEntityException is thrown, the EJB container wraps it in a RemoteException before returning it to the client.

In the SavingsAccountBean class, ejbLoad invokes the loadRow method, which issues a SQL SELECT statement and assigns the retrieved data to the instance variables. The ejbStoremethod calls the storeRow method, which stores the instance variables in the database with a SQL UPDATE statement. Here is the code for the ejbLoad and ejbStore methods:

public void ejbLoad() {

   try {
      loadRow();
   } catch (Exception ex) {
      throw new EJBException("ejbLoad: " + 
         ex.getMessage());
   }
}

public void ejbStore() {

   try {
      storeRow();
   } catch (Exception ex) {
      throw new EJBException("ejbStore: " + 
         ex.getMessage());
   }
}