CMP Entity Bean

Java Primer
Incremental J2EE
by Vince Huston
Listing 8. CMP Entity Bean.


// Purpose.  CMP Entity Bean

import java.util.*;
import java.rmi.RemoteException;
import javax.ejb.*;

interface RIItem extends EJBObject {
   public String getSummary() throws RemoteException;
   public int    order()      throws RemoteException;
}

interface HIItem extends EJBHome {
   RIItem create( Integer pk, String nm, int pr ) throws RemoteException, CreateException;
   Collection findAllInstances()                  throws RemoteException, FinderException;
   RIItem     findByPrimaryKey( Integer pk )      throws RemoteException, FinderException;
}

public class ItemImpl implements EntityBean {
   transient private EntityContext context;
   public int    id;
   public String name;
   public int    price;
   public int    numSold;

   public Integer ejbCreate( Integer pk, String nm, int pr ) {
      id = pk.intValue();
      name = nm;
      price = pr;
      numSold = 0;
      System.out.println( "ItemImpl ejbCreate: " + id );
      return null;
   }
   public void ejbPostCreate( Integer pk, String nm, int pr ) {
      System.out.println( "ItemImpl ejbPostCreate: " + id );
   }

   public String getSummary() {
      return name + " $" + price + " ... " + numSold;
   }
   public int order() {
      numSold++;
      return price;
   }

   // from javax.ejb.SessionBean and EntityBean interfaces
   public void ejbRemove() { System.out.println( "ItemImpl ejbRemove: " + id ); }
   public void ejbActivate() {
      id = ((Integer)context.getPrimaryKey()).intValue();
      System.out.println( "ItemImpl ejbActivate: " + id );
   }
   public void ejbPassivate() { System.out.println( "ItemImpl ejbPassivate: " + id ); }
   public void setEntityContext( EntityContext ctx ) {
      System.out.println( "ItemImpl setEntityContext: " + id );
      context = ctx;
   }

   // from javax.ejb.EntityBean interface
   public void ejbLoad()  { System.out.println( "ItemImpl ejbLoad: " + id ); }
   public void ejbStore() { System.out.println( "ItemImpl ejbStore: " + id ); }
   public void unsetEntityContext() {
      System.out.println( "ItemImpl setEntityContext: " + id );
      context = null;
}  }



import java.util.*;
import java.rmi.RemoteException;
import javax.rmi.*;
import javax.ejb.*;
import javax.naming.*;

interface RIStore extends EJBObject {
   Collection getItems()            throws RemoteException;
   void       selectItem( int num ) throws RemoteException;
   String     placeOrder()          throws RemoteException;
}

interface HIStore extends EJBHome {
   public RIStore create() throws java.rmi.RemoteException, CreateException;
}

public class StoreImpl implements SessionBean {
   private ArrayList  itemList   = new ArrayList();
   private ArrayList  theChoices = new ArrayList();
   private SessionContext context;

   public void ejbCreate() {
      System.out.println( "ejbCreate:" );
      try {
         InitialContext ic = new InitialContext();
         Object obj      = ic.lookup( "ItemHome" );
         HIItem itemHome = (HIItem) PortableRemoteObject.narrow( obj, HIItem.class );
         Collection  col = itemHome.findAllInstances();
         if (col.size() > 0)
            for (Iterator it = col.iterator(); it.hasNext(); )
               itemList.add( it.next() );
         else {
            itemList.add( itemHome.create( new Integer(1), "Design Patterns by GOF .....", 35 ));
            itemList.add( itemHome.create( new Integer(2), "Using UML and Patterns .....", 30 ));
            itemList.add( itemHome.create( new Integer(3), "C++ for Deadend Careers .... ", 5 ));
            itemList.add( itemHome.create( new Integer(4), "Java for Resume Inflation ..", 10 ));
            itemList.add( itemHome.create( new Integer(5), "Practical Java .............", 20 ));
         }
      } catch (NamingException ex) { ex.printStackTrace();
      } catch (FinderException ex) { ex.printStackTrace();
      } catch (CreateException ex) { ex.printStackTrace();
      } catch (RemoteException ex) { ex.printStackTrace();
   }  }
   public Collection getItems() {
      Collection summary = new ArrayList();
      try {
         for (Iterator it = itemList.iterator(); it.hasNext(); )
            summary.add( ((RIItem)it.next()).getSummary() );
      } catch (RemoteException ex) { ex.printStackTrace(); }
      System.out.println( "\nreturning " + summary.size() + " items to client" );
      return summary;
   }
   public void selectItem( int num ) {
      theChoices.add( new Integer( num ) );
   }
   public String placeOrder() {
      StringBuffer sb = new StringBuffer();
      RIItem ele;
      String str;
      int    totalBill = 0;
      System.out.println();
      sb.append( "The following items were ordered:\n" );
      try {
         for (Iterator it = theChoices.iterator(); it.hasNext(); ) {
            ele = (RIItem) itemList.get( ((Integer)it.next()).intValue() );
            totalBill += ele.order();
            str = ele.getSummary();
            System.out.println( str );
            sb.append( "   " );
            sb.append( str );
            sb.append( '\n' );
         }
      } catch (RemoteException ex) { ex.printStackTrace(); }
      sb.append( "Total bill is $" + totalBill + "\n" );
      System.out.println( "returning " + theChoices.size()
         + " orders to client, bill is $" + totalBill + "\n" );
      return sb.toString();
   }

   // from javax.ejb.SessionBean interface
   public void ejbRemove()    { System.out.println( "ejbRemove:" ); }
   public void ejbActivate()  { System.out.println( "ejbActivate:" ); }
   public void ejbPassivate() { System.out.println( "ejbPassivate:" ); }
   public void setSessionContext( SessionContext ctx ) {
      System.out.println( "setSessionContext:" );
      context = ctx;
}  }

/***************
setSessionContext:
ejbCreate:
item.getName is _HIItem_Stub
item instanceof HIItem is true
ItemImpl setEntityContext: 0
ItemImpl ejbCreate: 1
ItemImpl ejbPostCreate: 1
ItemImpl setEntityContext: 0
ItemImpl ejbCreate: 2
ItemImpl ejbPostCreate: 2
ItemImpl setEntityContext: 0
ItemImpl ejbCreate: 3
ItemImpl ejbPostCreate: 3
ItemImpl setEntityContext: 0
ItemImpl ejbCreate: 4
ItemImpl ejbPostCreate: 4
ItemImpl setEntityContext: 0
ItemImpl ejbCreate: 5
ItemImpl ejbPostCreate: 5

returning 5 items to client

Design Patterns by GOF ..... $35 ... 1
Using UML and Patterns ..... $30 ... 1
C++ for Deadend Careers ....  $5 ... 1
returning 3 orders to client, bill is $70

setSessionContext:
ejbCreate:
ItemImpl setEntityContext: 0

returning 5 items to client

Design Patterns by GOF ..... $35 ... 2
Using UML and Patterns ..... $30 ... 2
returning 2 orders to client, bill is $65

setSessionContext:
ejbCreate:

returning 5 items to client

Design Patterns by GOF ..... $35 ... 3
returning 1 orders to client, bill is $35

setSessionContext:
ejbCreate:

returning 5 items to client

returning 0 orders to client, bill is $0
***************/



import java.util.*;
import java.io.*;
import javax.rmi.*;
import javax.naming.*;
import javax.ejb.CreateException;

public class StoreClient {
   public static void main( String[] args ) {
      BufferedReader in = new BufferedReader(
                             new InputStreamReader( System.in ) );
      int choice;
      try {
         InitialContext ic = new InitialContext();
         Object     obj       = ic.lookup( "StoreHome" );
         HIStore    storeHome = (HIStore) PortableRemoteObject.narrow( obj, HIStore.class );
         RIStore    theStore  = storeHome.create();
         Collection theItems  = theStore.getItems();

         System.out.println( "Select from (0 when done):" );
         Iterator it = theItems.iterator();
         for (int i=1; it.hasNext(); i++)
            System.out.println( "   " + i + " - " + it.next() );

         while (true) {
            System.out.print( "Choice: " );
            if ((choice = Integer.parseInt( in.readLine() )) == 0) break;
            theStore.selectItem( choice-1 );
         }

         System.out.println( theStore.placeOrder() );

      } catch (NamingException ex ) { ex.printStackTrace();
      } catch (CreateException ex ) { ex.printStackTrace();
      } catch (IOException ex )     { ex.printStackTrace();
}  }  }

/***************
D:\j2ee\article\cmp> java StoreClient
Select from (0 when done):
   1 - Design Patterns by GOF ..... $35 ... 0
   2 - Using UML and Patterns ..... $30 ... 0
   3 - C++ for Deadend Careers ....  $5 ... 0
   4 - Java for Resume Inflation .. $10 ... 0
   5 - Practical Java ............. $20 ... 0
Choice: 1
Choice: 2
Choice: 3
Choice: 0
The following items were ordered:
   Design Patterns by GOF ..... $35 ... 1
   Using UML and Patterns ..... $30 ... 1
   C++ for Deadend Careers ....  $5 ... 1
Total bill is $70


D:\j2ee\article\cmp> java StoreClient
obj.getName is _HIStore_Stub
obj instanceof HIStore is true
Select from (0 when done):
   1 - Design Patterns by GOF ..... $35 ... 1
   2 - Using UML and Patterns ..... $30 ... 1
   3 - C++ for Deadend Careers ....  $5 ... 1
   4 - Java for Resume Inflation .. $10 ... 0
   5 - Practical Java ............. $20 ... 0
Choice: 1
Choice: 2
Choice: 0
The following items were ordered:
   Design Patterns by GOF ..... $35 ... 2
   Using UML and Patterns ..... $30 ... 2
Total bill is $65


D:\j2ee\article\cmp> java StoreClient
obj.getName is _HIStore_Stub
obj instanceof HIStore is true
Select from (0 when done):
   1 - Design Patterns by GOF ..... $35 ... 2
   2 - Using UML and Patterns ..... $30 ... 2
   3 - C++ for Deadend Careers ....  $5 ... 1
   4 - Java for Resume Inflation .. $10 ... 0
   5 - Practical Java ............. $20 ... 0
Choice: 1
Choice: 0
The following items were ordered:
   Design Patterns by GOF ..... $35 ... 3
Total bill is $35


D:\j2ee\article\cmp> java StoreClient
obj.getName is _HIStore_Stub
obj instanceof HIStore is true
Select from (0 when done):
   1 - Design Patterns by GOF ..... $35 ... 3
   2 - Using UML and Patterns ..... $30 ... 2
   3 - C++ for Deadend Careers ....  $5 ... 1
   4 - Java for Resume Inflation .. $10 ... 0
   5 - Practical Java ............. $20 ... 0
Choice: 0
The following items were ordered:
Total bill is $0
***************/

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