BMP Entity bean prob.

Prøv og post hvad du har. Så kommenterer vi.

PS: hvorfor BMP og ikke CMP ?

Smider lige et eksempel som jeg har kigget lidt på. (Er fra bogen Enterprise JavaBeans)


import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.ejb.EntityContext;
import java.sql.SQLException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import javax.sql.DataSource;
import javax.ejb.CreateException;
import javax.ejb.EJBException;
import javax.ejb.FinderException;
import javax.ejb.ObjectNotFoundException;
import java.util.Vector;
import java.util.Collection;

public class ShipBean implements javax.ejb.EntityBean
{
 
  public Integer id;
  public String name;
  public int capacity;
  public double tonnage;
 
  public EntityContext context;
 
  public Integer ejbCreate (Integer id, String name,
                            int capacity, double tonnage)
  throws CreateException
  {     
      System.out.println ("ejbCreate() pk="+id+" name="+name);
     
      if ((id.intValue () < 1) || (name == null))
        throw new CreateException ("Invalid Parameters");
     
      this.id = id;
      this.name = name;
      this.capacity = capacity;
      this.tonnage = tonnage;
     
      Connection con = null;
      PreparedStatement ps = null;
      try
      {
        con = this.getConnection ();
        ps = con.prepareStatement ("insert into Ship (id, name, capacity, tonnage) values (?,?,?,?)");
       
        ps.setInt (1, id.intValue ());
        ps.setString (2, name);
        ps.setInt (3, capacity);
        ps.setDouble (4, tonnage);
       
        if (ps.executeUpdate () != 1)
        {
            throw new CreateException ("Failed to add Ship to database");
        }
       
        return id;
      }
      catch (SQLException se)
      {
        throw new EJBException (se);
      }
      finally
      {
        try { if (ps != null) ps.close (); } catch (Exception e) {}
        try { if (con != null) con.close (); } catch (Exception e) {}
      }
  }
 
  public void ejbPostCreate (Integer id, String name,
  int capacity, double tonnage)
  {
      // Do something useful with the primary key.
  }
 
  public Integer ejbCreate (Integer id, String name )
  throws CreateException
  {
      return ejbCreate (id,name,0,0);
  }
 
  public void ejbPostCreate (Integer id, String name)
  {
      // Do something useful with the EJBObject reference.
  }
 
  public Integer ejbFindByPrimaryKey (Integer primaryKey)
  throws FinderException
  {
     
      System.out.println ("ejbFindByPrimaryKey() primaryKey="+primaryKey);

      Connection con = null;
      PreparedStatement ps = null;
      ResultSet result = null;

      try
      {
        con = this.getConnection ();
        ps = con.prepareStatement ("select id from Ship where id = ?");

        ps.setInt (1, primaryKey.intValue ());
       
        result = ps.executeQuery ();
       
        // Does ship id exist in database?
        if (!result.next ())
        {
            throw new ObjectNotFoundException ("Cannot find Ship with id = "+id);
        }
      } catch (SQLException se)
      {
        throw new EJBException (se);
      }
      finally
      {
        try { if (result != null) result.close (); } catch (Exception e) {}
        try { if (ps != null) ps.close (); } catch (Exception e) {}
        try { if (con != null) con.close (); } catch (Exception e) {}
      }
      return primaryKey;
  }
 
  public Collection ejbFindByCapacity (int capacity)
  throws FinderException
  {
     
      System.out.println ("ejbFindByCapacity() capacity="+capacity);
     
      Connection con = null;
      PreparedStatement ps = null;
      ResultSet result = null;
     
      try
      {
        con = this.getConnection ();
        ps = con.prepareStatement ("select id from Ship where capacity = ?");
       
        ps.setInt (1,capacity);
       
        result = ps.executeQuery ();
        Vector keys = new Vector ();
        while(result.next ())
        {
            keys.addElement (result.getObject ("id"));
        }
        return keys;
       
      }
      catch (SQLException se)
      {
        throw new EJBException (se);
      }
      finally
      {
        try { if (result != null) result.close (); } catch (Exception e) {}
        try { if (ps != null) ps.close (); } catch (Exception e) {}
        try { if (con != null) con.close (); } catch (Exception e) {}
      }
  }
 
  public void setEntityContext (EntityContext ctx)
  {
      context = ctx;
  }
  public void unsetEntityContext ()
  {
      context = null;
  }
  public void ejbActivate ()
  {}
  public void ejbPassivate ()
  {}
 
  public void ejbLoad ()
  {
     
      Integer primaryKey = (Integer)context.getPrimaryKey ();
      System.out.println ("ejbLoad() pk="+primaryKey);
     
      Connection con = null;
      PreparedStatement ps = null;
      ResultSet result = null;
      try
      {
        con = this.getConnection ();
        ps = con.prepareStatement ("select name, capacity, tonnage from Ship where id = ?");
       
        ps.setInt (1, primaryKey.intValue ());
        result = ps.executeQuery ();
       
        if (result.next ())
        {
            id = primaryKey;
            name = result.getString ("name");
            capacity = result.getInt ("capacity");
            tonnage = result.getDouble ("tonnage");
        } else
        {
            throw new EJBException ();
        }
      } catch (SQLException se)
      {
        throw new EJBException (se);
      }
      finally
      {
        try { if (result != null) result.close (); } catch (Exception e) {}
        try { if (ps != null) ps.close (); } catch (Exception e) {}
        try { if (con != null) con.close (); } catch (Exception e) {}
      }
  }
 
  public void ejbStore ()
  {
     
      System.out.println ("ejbStore() pk="+id);

      Connection con = null;
      PreparedStatement ps = null;
      try
      {
        con = this.getConnection ();
        ps = con.prepareStatement ("update Ship set name = ?, capacity = ?, tonnage = ? where id = ?");
       
        ps.setString (1,name);
        ps.setInt (2,capacity);
        ps.setDouble (3,tonnage);
        ps.setInt (4,id.intValue ());
       
        if (ps.executeUpdate () != 1)
        {
            throw new EJBException ("ejbStore unable to update table");
        }
      }
      catch (SQLException se)
      {
        throw new EJBException (se);
      }
      finally
      {
        try { if (ps != null) ps.close (); } catch (Exception e) {}
        try { if (con != null) con.close (); } catch (Exception e) {}
      }
  }
 
  public void ejbRemove ()
  {
     
      System.out.println ("ejbRemove() pk="+id);

      Connection con = null;
      PreparedStatement ps = null;
      try
      {
        con = this.getConnection ();
        ps = con.prepareStatement ("delete from Ship where id = ?");
       
        ps.setInt (1, id.intValue ());
       
        if (ps.executeUpdate () != 1)
        {
            throw new EJBException ("ejbRemove unable to remove bean");
        }
      }
      catch (SQLException se)
      {
        throw new EJBException (se);
      }
      finally
      {
        try { if (ps != null) ps.close (); } catch (Exception e) {}
        try { if (con != null) con.close (); } catch (Exception e) {}
      }
  }
 
  public String getName ()
  {
      System.out.println ("getName()");
      return name;
  }
  public void setName (String n)
  {
      System.out.println ("setName()");
      name = n;
  }
  public void setCapacity (int cap)
  {
      System.out.println ("setCapacity()");
      capacity = cap;
  }
  public int getCapacity ()
  {
      System.out.println ("getCapacity()");
      return capacity;
  }
  public double getTonnage ()
  {
      System.out.println ("getTonnage()");
      return tonnage;
  }
  public void setTonnage (double tons)
  {
      System.out.println ("setTonnage()");
      tonnage = tons;
  }
 
  public void ejbHomeMakeDbTable () throws SQLException
  {
      PreparedStatement ps = null;
      Connection con = null;
     
      try
      {
        con = this.getConnection ();
       
        System.out.println("Creating table SHIP...");
        ps = con.prepareStatement ("CREATE TABLE SHIP ( " +
        "ID INT PRIMARY KEY, " +
        "NAME CHAR(30), " +
        "TONNAGE DECIMAL (8,2), " +
        "CAPACITY INT" +
        ")" );
        ps.execute ();
        System.out.println("...done!");
      }
      finally
      {
        try { if (ps != null) ps.close (); } catch (Exception e) {}
        try { if (con != null) con.close (); } catch (Exception e) {}
      }
  }
 
  public void ejbHomeDeleteDbTable ()  throws SQLException
  {
      PreparedStatement ps = null;
      Connection con = null;
     
      try
      {
        con = this.getConnection ();
       
        System.out.println("Dropping table SHIP...");
        ps = con.prepareStatement ("DROP TABLE SHIP");
        ps.execute ();
        System.out.println("...done!");
      }
      finally
      {
        try { if (ps != null) ps.close (); } catch (Exception e) {}
        try { if (con != null) con.close (); } catch (Exception e) {}
      }
  }
 
  private Connection getConnection () throws SQLException
  {
      try
      {
        Context jndiCntx = new InitialContext ();
        DataSource ds =
        (DataSource)jndiCntx.lookup ("java:comp/env/jdbc/titanDB");       
        return ds.getConnection ();
      }
      catch (NamingException ne)
      {
        throw new EJBException (ne);
      }
  }
 
}

import javax.ejb.CreateException;
import javax.ejb.FinderException;
import java.rmi.RemoteException;
import java.util.Collection;

public interface ShipHomeRemote extends javax.ejb.EJBHome
{

  public ShipRemote create(Integer id, String name,
                            int capacity, double tonnage)
      throws RemoteException, CreateException;

  public ShipRemote create(Integer id, String name)
      throws RemoteException, CreateException;

  public ShipRemote findByPrimaryKey(Integer primaryKey)
      throws FinderException, RemoteException;

  public Collection findByCapacity(int capacity)
      throws FinderException, RemoteException;

  // Utility methods for database table creation/deletion
  // (this is specific to the JBoss workbook to make testing easier)
  //
  public void makeDbTable() throws RemoteException;

  public void deleteDbTable() throws RemoteException;
}

import java.rmi.RemoteException;

public interface ShipRemote extends javax.ejb.EJBObject
{
    public String getName() throws RemoteException;
    public void setName(String name) throws RemoteException;
    public void setCapacity(int cap) throws RemoteException;
    public int getCapacity() throws RemoteException;
    public double getTonnage() throws RemoteException;
    public void setTonnage(double tons) throws RemoteException;
}

!!! Klienten  !!!!


package com.titan.clients;


import com.titan.ship.*;

import java.rmi.RemoteException;

import javax.naming.InitialContext;
import javax.naming.Context;
import javax.naming.NamingException;
import javax.rmi.PortableRemoteObject;


public class Client
{

  public static void main (String [] args)
  {
      try
      {
        Context jndiContext = getInitialContext ();

        Object ref = jndiContext.lookup ("ShipHomeRemote");
        ShipHomeRemote home = (ShipHomeRemote)
        PortableRemoteObject.narrow (ref,ShipHomeRemote.class);

        // We check if we have to build the database schema...
        //
        if ( (args.length > 0) && args[0].equalsIgnoreCase ("CreateDB") )
        {
            System.out.println ("Creating database table...");
            home.makeDbTable ();
        }
        // ... or if we have to drop it...
        //
        else if ( (args.length > 0) && args[0].equalsIgnoreCase ("DropDB") )
        {
            System.out.println ("Dropping database table...");
            home.deleteDbTable ();
        }
        else
        {
            // ... standard behavior
            //
            System.out.println ("Creating Ship 101..");
            ShipRemote ship1 = home.create (new Integer (101),"Edmund Fitzgerald");

            ship1.setTonnage (50000.0);
            ship1.setCapacity (300);

            Integer pk = new Integer (101);

            System.out.println ("Finding Ship 101 again..");
            ShipRemote ship2 = home.findByPrimaryKey (pk);

            System.out.println (ship2.getName ());
            System.out.println (ship2.getTonnage ());
            System.out.println (ship2.getCapacity ());

            System.out.println ("ship1.equals (ship2) == " +
            ship1.equals (ship2));

            System.out.println ("Removing Ship 101..");
            ship2.remove ();
        }

      } catch (java.rmi.RemoteException re)
      {
        re.printStackTrace ();
      }
      catch (javax.naming.NamingException ne)
      {
        ne.printStackTrace ();
      }
      catch (javax.ejb.CreateException ce)
      {
        ce.printStackTrace ();
      }
      catch (javax.ejb.FinderException fe)
      {
        fe.printStackTrace ();
      }
      catch (javax.ejb.RemoveException re)
      {
        re.printStackTrace ();
      }
  }

  public static Context getInitialContext ()
  throws javax.naming.NamingException
  {
      return new javax.naming.InitialContext ();
  }
}

Men som arne skriver hvorfor ikke bruge CMP(Container Managed Persistence) ?
Så "slipper" du for at skrive det meste at dine SQL statements. Eftersigende skulle man spare cirka 40% ved at bruge CMP i forhold til BMP.

Sorry er først inde og kigge nu og har selv lavet en løsning.

Men jeg løste problemet ved at lave en finder metode der retunerede alle posterne.

Kode >>

package vare;

import javax.ejb.*;
import java.sql.*;
import java.util.*;

public class VareBean implements EntityBean, VareRemoteBusiness
{
    private javax.ejb.EntityContext context;
   
    private Connection con;
    private Integer varenummer;
    private String beskrivelse;
    private String pris;
   
    public void setEntityContext(EntityContext aContext)
    {
        context = aContext;
    }
   
    public void ejbActivate()
    {
        varenummer = (Integer) context.getPrimaryKey();
    }
   
    public void ejbPassivate()
    {
        varenummer = null;
    }

    public void ejbRemove()
    {

    }

    public void unsetEntityContext()
    {
        context = null;
    }

    public void ejbLoad()
    {
        try{ loadRow(); }
        catch(SQLException e){ throw new EJBException("Somethings wrong !!"); }
    }
   
    public void ejbStore()
    {

    }

    public Integer getVarenummer()
    {
        return varenummer;
    }
   
    public String getBeskrivelse()
    {
        return beskrivelse;
    }
   
    public String getPris()
    {
        return pris;
    }
   
    public Integer ejbFindByPrimaryKey(Integer aKey) throws FinderException
    {
        boolean found;
       
        try
        {
            connect();
            String sql_str          = "select varenr from vare where varenr=?";
            PreparedStatement ps    = con.prepareStatement(sql_str);
            ps.setInt(1, aKey.intValue());
       
            ResultSet rs    = ps.executeQuery();
            found          = rs.next();
       
            rs.close();
            ps.close();
            disConnect();
        }
        catch(SQLException e) { throw new EJBException(e.getMessage()); }
       
        if(found)
            return aKey;
        else
            throw new ObjectNotFoundException(aKey + " not found.");
    }
   
    public java.util.Collection ejbFindAll() throws FinderException, SQLException
    {
        ArrayList result = new ArrayList();
       
        connect();
        Statement stmt  = con.createStatement();
        String sql_str  = "select * from vare";
        ResultSet rs    = stmt.executeQuery(sql_str);

        while(rs.next())
        {
            int varenummer      = rs.getInt(1);
            result.add(new Integer(varenummer));
        }

        rs.close();
        stmt.close();
        disConnect();
       
        return result;
    }
   
    private void loadRow() throws SQLException
    {
        connect();
        String sql_str          = "select * from vare where varenr=?";
        PreparedStatement ps    = con.prepareStatement(sql_str);
        ps.setInt(1, varenummer.intValue());
        ResultSet rs            = ps.executeQuery();
       
        if(rs.next())
        {
            varenummer  = new Integer(rs.getInt(1));
            beskrivelse = rs.getString(2);
            pris        = rs.getString(3);
        }
        else
        {
            throw new NoSuchEntityException("Row not found");
        }
       
        rs.close();
        ps.close();
        disConnect();
    }

    private javax.sql.DataSource getDB() throws javax.naming.NamingException
    {
        javax.naming.Context c = new javax.naming.InitialContext();
        return (javax.sql.DataSource) c.lookup("java:comp/env/jdbc/DB");
    }
   
    private void connect()
    {
        try { con = getDB().getConnection(); }
        catch(Exception e) { throw new EJBException(e.getMessage()); }
    }
   
    private void disConnect()
    {
        try { con.close(); }
        catch(SQLException e) { throw new EJBException(e.getMessage()); }
    }
}

P.s. Det var en opgave der skulle løses og BMP skulle bruges ..