AccountHome.create(), the container allocates an instance
* of this bean and calls AccountBean.ejbCreate().
*
* For bean-managed persistence, ejbCreate() returns
* a primary key, unlike the case of container-managed
* persistence, where it returns a void.
*
* @param accountID String Account ID
* @param initialBalance double Initial Balance
* @return String Primary Key
* @exception javax.ejb.CreateException
* if there is a problem creating the bean
* @exception javax.ejb.DuplicateKeyException
* if a create is attempted using a Primary Key
* already in the database
* @exception javax.ejb.EJBException
* if there is a communications or systems failure
*/
public String ejbCreate(String accountId, double initialBalance)
throws CreateException
{
log("AccountBean.ejbCreate( id = accountId" + ", " + "initial balance = $ " + initialBalance + ")");
this.accountId = accountId;
this.balance = initialBalance;
Connection con = null;
PreparedStatement ps = null;
try {
con = getConnection();
ps = con.prepareStatement("insert into ejbAccounts (id, bal) values (?, ?)");
ps.setString(1, accountId);
ps.setDouble(2, balance);
if (ps.executeUpdate() != 1) {
String error = "JDBC did not create any row";
log(error);
throw new CreateException (error);
}
return accountId;
} catch (SQLException sqe) {
// Check to see if this SQLException is due to a unique constraint
// violation on our database table (ie. there is already a pk with the
// value of accountId in the table). If so, throw a
// DuplicateKeyException else throw a CreateException.
try {
ejbFindByPrimaryKey(accountId);
} catch(ObjectNotFoundException onfe) {
String error = "SQLException: " + sqe;
log(error);
throw new CreateException (error);
}
String error = "An Account already exists in the database with Primary Key " + accountId;
log(error);
throw new DuplicateKeyException(error);
} finally {
cleanup(con, ps);
}
}
/**
* Required by the EJB specification, this method is not used
* by this example.
*
* @param accountID String Account Identification
* @param initialBalance double Initial Balance
*/
public void ejbPostCreate(String accountId, double initialBalance) {
log("ejbPostCreate (" + id() + ")");
}
/**
* Deletes the EJBean from the persistent storage.
*
* @exception javax.ejb.NoSuchEntityException
* if the bean is not found in the database
* @exception javax.ejb.EJBException
* if there is a communications or systems failure
*/
public void ejbRemove() {
log("ejbRemove (" + id() + ")");
// we need to get the primary key from the context because
// it is possible to do a remove right after a find, and
// ejbLoad may not have been called.
Connection con = null;
PreparedStatement ps = null;
try {
con = getConnection();
accountId = (String) ctx.getPrimaryKey();
ps = con.prepareStatement("delete from ejbAccounts where id = ?");
ps.setString(1, accountId);
if (!(ps.executeUpdate() > 0)) {
String error = "AccountBean (" + accountId + " not found";
log(error);
throw new NoSuchEntityException (error);
}
} catch (SQLException sqe) {
log("SQLException: " + sqe);
throw new EJBException (sqe);
} finally {
cleanup(con, ps);
}
}
/**
* Attempts to find the EJBean with a given Primary Key from
* the persistent storage.
*
* @param pk String Primary Key
* @return String Primary Key
* @exception javax.ejb.ObjectNotFoundException
* thrown if the EJBean cannot be found
* @exception javax.ejb.EJBException
* if there is a communications or systems failure
*/
public String ejbFindByPrimaryKey(String pk)
throws ObjectNotFoundException
{
log("ejbFindByPrimaryKey (" + pk + ")");
Connection con = null;
PreparedStatement ps = null;
try {
con = getConnection();
ps = con.prepareStatement("select bal from ejbAccounts where id = ?");
ps.setString(1, pk);
ps.executeQuery();
ResultSet rs = ps.getResultSet();
if (rs.next()) {
balance = rs.getDouble(1);
} else {
String error = "ejbFindByPrimaryKey: AccountBean (" + pk + ") not found";
log(error);
throw new ObjectNotFoundException (error);
}
} catch (SQLException sqe) {
log("SQLException: " + sqe);
throw new EJBException (sqe);
} finally {
cleanup(con, ps);
}
log("ejbFindByPrimaryKey (" + pk + ") found");
return pk;
}
/**
* Finds all EJBeans with a balance greater than a given amount.
* Returns an Enumeration of found EJBean primary keys.
*
* @param balanceGreaterThan double Test Amount
* @return Enumeration EJBean Primary Keys
* @exception javax.ejb.EJBException
* if there is a communications or systems failure
*/
public Enumeration ejbFindBigAccounts(double balanceGreaterThan) {
log("ejbFindBigAccounts (balance > " + balanceGreaterThan + ")");
Connection con = null;
PreparedStatement ps = null;
try {
con = getConnection();
ps = con.prepareStatement("select id from ejbAccounts where bal > ?");
ps.setDouble(1, balanceGreaterThan);
ps.executeQuery();
ResultSet rs = ps.getResultSet();
Vector v = new Vector();
String pk;
while (rs.next()) {
pk = rs.getString(1);
v.addElement(pk);
}
return v.elements();
} catch (SQLException sqe) {
log("SQLException: " + sqe);
throw new EJBException (sqe);
} finally {
cleanup(con, ps);
}
}
/**
* Adds amount to balance.
*
* @param amount double Amount
* @return double balance
*/
public double deposit(double amount) {
log("Depositing $" + amount + " into '" + accountId + "'");
balance += amount;
return balance;
}
/**
* Subtracts amount from balance.
*
* @param amount double Amount
* @return double Balance
* @exception ProcessingErrorException
* if Amount > Balance.
*/
public double withdraw(double amount)
throws ProcessingErrorException
{
log("Withdrawing $" + amount + " from '" + accountId + "'");
if (amount > balance) {
String error = "Request to withdraw $" + amount +
" more than balance " + balance + " in account " + accountId;
log(error);
throw new ProcessingErrorException(error);
}
balance -= amount;
return balance;
}
/**
* Returns current balance.
*
* @return double Balance
*/
public double balance() {
return balance;
}
/**
* Gets current connection to the connection pool.
*
* @return Connection
* @exception javax.ejb.EJBException
* if there is a communications or systems failure
*/
private Connection getConnection()
throws SQLException
{
InitialContext initCtx = null;
try {
initCtx = new InitialContext();
DataSource ds = (javax.sql.DataSource)
initCtx.lookup("java:comp/env/jdbc/demoPool");
return ds.getConnection();
} catch(NamingException ne) {
log("UNABLE to get a connection from demoPool!");
log("Please make sure that you have setup the connection pool properly");
throw new EJBException(ne);
} finally {
try {
if(initCtx != null) initCtx.close();
} catch(NamingException ne) {
log("Error closing context: " + ne);
throw new EJBException(ne);
}
}
}
// You might also consider using WebLogic's log service
private void log(String s) {
if (VERBOSE) System.out.println(s);
}
// Return a String that contains this beans id
private String id() {
return "PK = " + (String) ctx.getPrimaryKey();
}
private void cleanup(Connection con, PreparedStatement ps) {
try {
if (ps != null) ps.close();
} catch (Exception e) {
log("Error closing PreparedStatement: "+e);
throw new EJBException (e);
}
try {
if (con != null) con.close();
} catch (Exception e) {
log("Error closing Connection: " + e);
throw new EJBException (e);
}
}
}