关于EJB返回值的解决方案

/** 
> * 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); 
> } 
> } 

／／／／／／／／／／／／／server端／／／／／／／／／／／／／ 
package example4; 
import java.sql.*; 
import javax.sql.*; 
import sun.jdbc.rowset.*; 
import javax.naming.*; 
import javax.ejb.*; 
public class CoffeesBean implements SessionBean { 
   private SessionContext sc = null; 
   private Context ctx = null; 
   private DataSource ds = null; 
   public CoffeesBean () {} 
   public void ejbCreate() throws CreateException { 
   try { 
   ctx = new InitialContext(); 
   ds = (DataSource)ctx.lookup("jdbc/CoffeesDB"); 
   } 
   catch (Exception e) { 
   System.out.println(e.getMessage()); 
   throw new CreateException(); 
   } 
   } 
   public RowSet getCoffees() throws SQLException { 
   Connection con = null; 
ResultSet rs; 
   CachedRowSet crs; 
   try { 
   con = ds.getConnection("webCustomer", "webPassword"); 
   Statement stmt = con.createStatement(); 
   rs = stmt.executeQuery("select * from coffees"); 
   crs = new CachedRowSet(); 
   crs.populate(rs); 
   // the writer needs this because JDBC drivers 
   // don't provide this meta-data. 
   crs.setTableName("coffees"); 
   rs.close(); 
   stmt.close(); 
   } finally { 
   if (con != null) 
   con.close(); 
   } 
   return rset; 
   } 
   public updateCoffees(RowSet rs) throws SQLException { 
   Connection con = null; 
   try { 
   CachedRowSet crs = (CachedRowSet)rs; 
   con = ds.getConnection("webCustomer", "webPassword"); 
   // moves the changes back to the database 
   crs.acceptChanges(con); 
   } finally { 
   if (con != null) 
   con.close(); 
   } 
   } 
   // 
   // Methods inherited from SessionBean 
   // 
   public void setSessionContext(SessionContext sc) { 
   this.sc = sc; 
   } 
   public void ejbRemove() {} 
   public void ejbPassivate() {} 
   public void ejbActivate() {} 
} 
／／／／／／／／／／／／／／／／／／client端／／／／／／／／／／／／／／ 
package example4; 
import java.sql.*; 
import javax.sql.*; 
import sun.jdbc.rowset.*; 
import javax.naming.*; 
import javax.ejb.*; 
import javax.rmi.*; 
class CoffeesClient { 
   public static void main(String[] args) { 
   try { 
   // init the bean 
   Context ctx = new InitialContext(); 
   Object obj = ctx.lookup("ejb/Coffees"); 
   CoffeesHome coffeesHome = (CoffeesHome) 
   PortableRemoteObject.narrow(obj, CoffeesHome.class); 
   Coffees coffees = coffeesHome.create(); 
   // get the rowset from the bean 
   CachedRowSet rset = (CachedRowSet)coffees.getCoffees(); 
   // find the Columbian coffee 
   while (rset.next()) { 
   String coffeeName = rset.getString("COF_NAME"); 
   if (coffeeName.equalsIgnoreCase(new String("Columbian"))) { 
   // columbian coffee has gone up 10% 
   rset.updateFloat("PRICE", 
(float)(rset.getFloat("PRICE") * 1.10)); 
   rset.updateRow(); 
   } 
   } 
   // finally send the updated back to the bean... 
   System.out.println("Calling update method"); 
   coffees.updateCoffees((RowSet)rset); 
   } 
   catch (Exception e) { 
   System.out.println(e.getMessage()); 
   } 
   } 
}