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Example: Handling connection exceptions for BMP beans in container-managed database transactions

 

The following code sample demonstrates how to roll back transactions and issue exceptions to the bean client in cases of stale connection exceptions. 

//===================START_PROLOG======================================
//
//   5630-A23, 5630-A22,
//   (C) COPYRIGHT International Business Machines Corp. 2005
//   All Rights Reserved
//   Licensed Materials - Property of IBM
//   US Government Users Restricted Rights - Use, duplication or
//   disclosure restricted by GSA ADP Schedule Contract with IBM Corp.
//
//   IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
//   ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
//   PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR
//   CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
//   USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
//   OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE
//   OR PERFORMANCE OF THIS SOFTWARE.
//
//===================END_PROLOG========================================
 package WebSphereSamples.ConnPool;
 import java.util.*; import javax.ejb.*; import java.sql.*; import javax.sql.*; import javax.ejb.*; import javax.naming.*;

/**
 * This is an Entity Bean class with five BMP fields
 * String firstName, String lastName, String middleInit
 * String empNo, int edLevel
 */ public class EmployeeBMPBean implements EntityBean {
       private javax.ejb.EntityContext entityContext = null;
       final static long serialVersionUID = 3206093459760846163L;

       private java.lang.String firstName;
       private java.lang.String lastName;
       private String middleInit;
       private javax.sql.DataSource ds;
       private java.lang.String empNo;
       private int edLevel;
/**
 * ejbActivate method 
 * ejbActivate calls getDS(), which performs the 
 * JNDI lookup for the datasource.
 */ public void ejbActivate() {
       getDS();
}
/**
 * ejbCreate method for a BMP entity bean
 * @return WebSphereSamples.ConnPool.EmployeeBMPKey
 * @param key WebSphereSamples.ConnPool.EmployeeBMPKey
 * @exception javax.ejb.CreateException 
 */ public WebSphereSamples.ConnPool.EmployeeBMPKey ejbCreate(String empNo, 
String firstName, String lastName, String middleInit, int edLevel) throws  javax.ejb.CreateException {

   Connection conn = null;
   PreparedStatement ps = null;
       
   if (ds == null) getDS();
              
   this.empNo = empNo;
   this.firstName = firstName;
   this.lastName = lastName;
   this.middleInit = middleInit;
   this.edLevel = edLevel;

   String sql = "insert into Employee (empNo, firstnme, midinit, lastname,
        edlevel) values (?,?,?,?,?)";
              
   try {
      conn = ds.getConnection();
      ps = conn.prepareStatement(sql);                     
      ps.setString(1, empNo);
      ps.setString(2, firstName);
      ps.setString(3, middleInit);
      ps.setString(4, lastName);
      ps.setInt(5, edLevel);
              
 if (ps.executeUpdate() != 1){
         System.out.println("ejbCreate Failed to add user.");
         throw new CreateException("Failed to add user.");
      }   } 
   catch (com.ibm.websphere.ce.cm.StaleConnectionException se) {

// This exception indicates that the connection to the database is no longer valid.
// Rollback the transaction, and throw an exception to the client indicating they
// can retry the transaction if desired.

System.out.println("Stale Connection Exception during get connection or  process SQL: " +  se.getMessage());
      throw new CreateException(se.getMessage());   } 
   catch (SQLException sq) {
      System.out.println("SQL Exception during get connection or process SQL: " +
                          sq.getMessage());
   throw new CreateException(sq.getMessage());   } 
   finally {
      // Always close the connection in a finally statement to ensure proper 
      // closure in all cases. Closing the connection does not close an
      // actual connection, but releases it back to the pool for reuse.
  if (ps != null) {
         try {
            ps.close();
         } 
         catch (Exception e) {
            System.out.println("Close Statement Exception: " + e.getMessage());
         }
      }
      if (conn != null) {
         try {
            conn.close();
         } 
         catch (Exception e) {
            System.out.println("Close connection exception: " + e.getMessage());
         }
      }   }
   return new EmployeeBMPKey(this.empNo);
}
/**
 * ejbFindByPrimaryKey method
 * @return WebSphereSamples.ConnPool.EmployeeBMPKey
 * @param primaryKey WebSphereSamples.ConnPool.EmployeeBMPKey
 * @exception javax.ejb.FinderException
 */ public WebSphereSamples.ConnPool.EmployeeBMPKey
     ejbFindByPrimaryKey(WebSphereSamples.ConnPool.EmployeeBMPKey primaryKey)
                 javax.ejb.FinderException {
       loadByEmpNo(primaryKey.empNo);
       return primaryKey;
}
/**
 * ejbLoad method
 */ public void ejbLoad() {
       try {
              EmployeeBMPKey pk = (EmployeeBMPKey) entityContext.getPrimaryKey();
              loadByEmpNo(pk.empNo);
       } catch (FinderException fe) {
              throw new EJBException("Cannot load Employee state from database.");
       }       
}
/**
 * ejbPassivate method
 */ public void ejbPassivate() {}
/**
 * ejbPostCreate method for a BMP entity bean
 * @param key WebSphereSamples.ConnPool.EmployeeBMPKey
 */ public void ejbPostCreate(String empNo, String firstName, String lastName, String middleInit,
    int edLevel) {}
/**
 * ejbRemove method
 * @exception javax.ejb.RemoveException
 */ public void ejbRemove() throws javax.ejb.RemoveException {
       
   if (ds == null) 
      GetDS();

   String sql = "delete from Employee where empNo=?";
   Connection con = null;
   PreparedStatement ps = null;
 try {                     
      con = ds.getConnection();                                                               
      ps = con.prepareStatement(sql);                                          
      ps.setString(1, empNo);
      if (ps.executeUpdate() != 1){
         throw new EJBException("Cannot remove employee: " + empNo);
      }   } 
   catch (com.ibm.websphere.ce.cm.StaleConnectionException se) {

// This exception indicates that the connection to the database is no longer valid.
// Rollback the transaction, and throw an exception to the client indicating they
// can retry the transaction if desired.

System.out.println("Stale Connection Exception during get connection or  process SQL: " + se.getMessage());
      throw new EJBException(se.getMessage());   } 
   catch (SQLException sq) {
      System.out.println("SQL Exception during get connection or process SQL: " +
                          sq.getMessage());
      throw new EJBException(sq.getMessage());      } 
   finally {
      // Always close the connection in a finally statement to ensure proper 
      // closure in all cases. Closing the connection does not close an
      // actual connection, but releases it back to the pool for reuse.
      if (ps != null) {
         try {
            ps.close();
         } 
         catch (Exception e) {
            System.out.println("Close Statement Exception: " + e.getMessage());
         }
      }
      if (con != null) {
         try {
            con.close();
         } 
         catch (Exception e) {
            System.out.println("Close connection exception: " + e.getMessage());
         }
      }   }
}
 try {                     
      con = ds.getConnection();                                                
      ps = con.prepareStatement(sql);                                          
      ps.setString(1, empNo);
      if (ps.executeUpdate() != 1){
         throw new EJBException("Cannot remove employee: " + empNo);
      }   } 
   catch (com.ibm.websphere.ce.cm.StaleConnectionException se) {

// This exception indicates that the connection to the database is no longer valid.
// Rollback the transaction, and throw an exception to the client indicating they
// can retry the transaction if desired.

System.out.println("Stale Connection Exception during get connection or  process SQL: " + se.getMessage());
      throw new EJBException(se.getMessage());   } 
   catch (SQLException sq) {
      System.out.println("SQL Exception during get connection or process SQL: " +
                          sq.getMessage());
      throw new EJBException(sq.getMessage());      } 
   finally {
      // Always close the connection in a finally statement to ensure proper 
      // closure in all cases. Closing the connection does not close an
      // actual connection, but releases it back to the pool for reuse.
      if (ps != null) {
         try {
            ps.close();
         } 
         catch (Exception e) {
            System.out.println("Close Statement Exception: " + e.getMessage());
         }
      }
      if (con != null) {
         try {
            con.close();
         } 
         catch (Exception e) {
            System.out.println("Close connection exception: " + e.getMessage());
         }
      }   }
}
} 
   catch (com.ibm.websphere.ce.cm.StaleConnectionException se) {

// This exception indicates that the connection to the database is no longer valid.
// Rollback the transaction, and throw an exception to the client indicating they
// can retry the transaction if desired.

System.out.println("Stale Connection Exception during get connection or  process SQL: " + se.getMessage());
      throw new EJBException(se.getMessage());   } 
   catch (SQLException sq) {

      System.out.println("SQL Exception during get connection or process SQL: " +
                          sq.getMessage());
      throw new EJBException(sq.getMessage());   } 
   finally {
      // Always close the connection in a finally statement to ensure proper 
      // closure in all cases. Closing the connection does not close and 
      // actual connection, but releases it back to the pool for reuse.
      if (ps != null) {
         try {
            ps.close();
         } 
         catch (Exception e) {
            System.out.println("Close Statement Exception: " + e.getMessage());
         }
      }
      if (con != null) {
         try {
            con.close();
         } 
         catch (Exception e) {
            System.out.println("Close connection exception: " + e.getMessage());
         }
      }   }
}
/**
 * Get the employee's edLevel
 * Creation date: (4/20/2001 3:46:22 PM)
 * @return int
 */ public int getEdLevel() {
       return edLevel;
}
/**
 * getEntityContext method
 * @return javax.ejb.EntityContext
 */ public javax.ejb.EntityContext getEntityContext() {
       return entityContext;
}
/**
 * Get the employee's first name
 * Creation date: (4/19/2001 1:34:47 PM)
 * @return java.lang.String
 */ public java.lang.String getFirstName() {
       return firstName;
}
/**
 * Get the employee's last name
 * Creation date: (4/19/2001 1:35:41 PM)
 * @return java.lang.String
 */ public java.lang.String getLastName() {
       return lastName;
}
/**
* get the employee's middle initial
 * Creation date: (4/19/2001 1:36:15 PM)
 * @return char
 */ public String getMiddleInit() {
       return middleInit;
}
/**
 * Lookup the DataSource from JNDI
 * Creation date: (4/19/2001 3:28:15 PM)
 */ private void getDS() {
       try {
              Hashtable parms = new Hashtable();
              parms.put(Context.INITIAL_CONTEXT_FACTORY, 
                            "com.ibm.websphere.naming.WsnInitialContextFactory");
              InitialContext ctx = new InitialContext(parms);
              // Perform a naming service lookup to get the DataSource object.
              ds = (DataSource)ctx.lookup("java:comp/env/jdbc/SampleDB");
       } 
       catch (Exception e) {
              System.out.println("Naming service exception: " + e.getMessage());
              e.printStackTrace();
       }
}
/**
 * Load the employee from the database
 * Creation date: (4/19/2001 3:44:07 PM)
 * @param empNo java.lang.String
 */ private void loadByEmpNo(String empNoKey) throws javax.ejb.FinderException{

       String sql = "select empno, firstnme, midinit, lastname, edLevel from 
          employee where empno = ?";
       Connection conn = null;
       PreparedStatement ps = null;
       ResultSet rs = null;

       if (ds == null) getDS();
       
       try {
// Get a Connection object conn using the DataSource factory.
                 conn = ds.getConnection();
                // Run DB query using standard JDBC coding.
              ps = conn.prepareStatement(sql);
              ps.setString(1, empNoKey);
              rs = ps.executeQuery();
              if (rs.next()) {
                     empNo= rs.getString(1);
                     firstName=rs.getString(2);
                     middleInit=rs.getString(3);
                     lastName=rs.getString(4); 
                     edLevel=rs.getInt(5);
              } 
             else {
                throw new ObjectNotFoundException("Cannot find employee number " +
                                                   empNoKey);
             }
      } 
      catch (com.ibm.websphere.ce.cm.StaleConnectionException se) {

// This exception indicates that the connection to the database is no longer valid.
// Rollback the transaction, and throw an exception to the client indicating they
// can retry the transaction if desired.

System.out.println("Stale Connection Exception during get connection or  process SQL: " + se.getMessage());
         throw new FinderException(se.getMessage());
      } 
      catch (SQLException sq) {
System.out.println("SQL Exception during get connection or process SQL: " +
                               sq.getMessage());
         throw new FinderException(sq.getMessage());
      } 
      finally {
              // Always close the connection in a finally statement to ensure 
              // proper closure in all cases. Closing the connection does not 
              // close an actual connection, but releases it back to the pool 
              // for reuse.
         if (rs != null) {
            try {
               Rs.close();
            } 
            catch (Exception e) {
               System.out.println("Close Resultset Exception: " + e.getMessage());
            }
         }
         if (ps != null) {
            try {
               ps.close();
            } 
            catch (Exception e) {
               System.out.println("Close Statement Exception: " + e.getMessage());
            }
         }
         if (conn != null) {
            try {
               conn.close();
            } 
            catch (Exception e) {
               System.out.println("Close connection exception: " + e.getMessage());
            }
        }
     }      
}
/**
 * set the employee's education level
 * Creation date: (4/20/2001 3:46:22 PM)
 * @param newEdLevel int
 */ public void setEdLevel(int newEdLevel) {
       edLevel = newEdLevel;
}
/**
 * setEntityContext method
 * @param ctx javax.ejb.EntityContext
 */ public void setEntityContext(javax.ejb.EntityContext ctx) {
       entityContext = ctx;
}
/**
 * set the employee's first name
 * Creation date: (4/19/2001 1:34:47 PM)
 * @param newFirstName java.lang.String
 */ public void setFirstName(java.lang.String newFirstName) {
       firstName = newFirstName;
}
/**
 * set the employee's last name
 * Creation date: (4/19/2001 1:35:41 PM)
 * @param newLastName java.lang.String
 */ public void setLastName(java.lang.String newLastName) {
       lastName = newLastName;
}
/**
 * set the employee's middle initial
 * Creation date: (4/19/2001 1:36:15 PM)
 * @param newMiddleInit char
 */ public void setMiddleInit(String newMiddleInit) {
       middleInit = newMiddleInit;
}
/**
 * unsetEntityContext method
 */ public void unsetEntityContext() {
       entityContext = null;
}
}


//===================START_PROLOG======================================
//
//   5630-A23, 5630-A22,
//   (C) COPYRIGHT International Business Machines Corp. 2002
//   All Rights Reserved
//   Licensed Materials - Property of IBM
//   US Government Users Restricted Rights - Use, duplication or
//   disclosure restricted by GSA ADP Schedule Contract with IBM Corp.
//
//   IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
//   ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
//   PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR
//   CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
//   USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
//   OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE
//   OR PERFORMANCE OF THIS SOFTWARE.
//
//===================END_PROLOG========================================
 package WebSphereSamples.ConnPool;

/**
 * This is a Home interface for the Entity Bean
 */ public interface EmployeeBMPHome extends javax.ejb.EJBHome {

/**
 * 
 * @return WebSphereSamples.ConnPool.EmployeeBMP
 * @param empNo java.lang.String
 * @param firstName java.lang.String
 * @param lastName java.lang.String
 * @param middleInit java.lang.String
 * @param edLevel int 
 */ WebSphereSamples.ConnPool.EmployeeBMP create(java.lang.String empNo, java.lang.String firstName, 
 java.lang.String lastName, java.lang.String middleInit, int edLevel) throws
 javax.ejb.CreateException, java.rmi.RemoteException;
/**
 * findByPrimaryKey method comment
 * @return WebSphereSamples.ConnPool.EmployeeBMP
 * @param key WebSphereSamples.ConnPool.EmployeeBMPKey
 * @exception java.rmi.RemoteException
 * @exception javax.ejb.FinderException
 */ WebSphereSamples.ConnPool.EmployeeBMP
  findByPrimaryKey(WebSphereSamples.ConnPool.EmployeeBMPKey key) 
    throws java.rmi.RemoteException, javax.ejb.FinderException;
}



//===================START_PROLOG======================================
//
//   5630-A23, 5630-A22,
//   (C) COPYRIGHT International Business Machines Corp. 2002
//   All Rights Reserved
//   Licensed Materials - Property of IBM
//   US Government Users Restricted Rights - Use, duplication or
//   disclosure restricted by GSA ADP Schedule Contract with IBM Corp.
//
//   IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
//   ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
//   PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR
//   CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
//   USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
//   OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE
//   OR PERFORMANCE OF THIS SOFTWARE.
//
//===================END_PROLOG========================================
 package WebSphereSamples.ConnPool;

/**
 * This is an Enterprise Java Bean Remote Interface
 */ public interface EmployeeBMP extends javax.ejb.EJBObject {

/**
 * 
 * @return int
  */ int getEdLevel() throws java.rmi.RemoteException;
/**
 * 
 * @return java.lang.String
 */ java.lang.String getFirstName() throws java.rmi.RemoteException;
/**
 * 
 * @return java.lang.String
 */ java.lang.String getLastName() throws java.rmi.RemoteException;
/**
 * 
 * @return java.lang.String
 */ java.lang.String getMiddleInit() throws java.rmi.RemoteException;
/**
 * 
 * @return void
 * @param newEdLevel int
 */ void setEdLevel(int newEdLevel) throws java.rmi.RemoteException;
/**
 * 
 * @return void
 * @param newFirstName java.lang.String
 */ void setFirstName(java.lang.String newFirstName) throws java.rmi.RemoteException;
/**
 * 
 * @return void
 * @param newLastName java.lang.String
 */ void setLastName(java.lang.String newLastName) throws java.rmi.RemoteException;
/**
 * 
 * @return void
 * @param newMiddleInit java.lang.String
 */ void setMiddleInit(java.lang.String newMiddleInit) throws java.rmi.RemoteException;
}



//===================START_PROLOG======================================
//
//   5630-A23, 5630-A22,
//   (C) COPYRIGHT International Business Machines Corp. 2002
//   All Rights Reserved
//   Licensed Materials - Property of IBM
//   US Government Users Restricted Rights - Use, duplication or
//   disclosure restricted by GSA ADP Schedule Contract with IBM Corp.
//
//   IBM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
//   ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
//   PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL, INDIRECT OR
//   CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
//   USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
//   OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE
//   OR PERFORMANCE OF THIS SOFTWARE.
//
//===================END_PROLOG========================================
 package WebSphereSamples.ConnPool;

/**
* This is a Primary Key Class for the Entity Bean
**/ public class EmployeeBMPKey implements java.io.Serializable { 
  public String empNo;
  final static long serialVersionUID = 3206093459760846163L;

/**
* EmployeeBMPKey() constructor 
*/ public EmployeeBMPKey()  {
}
/**
* EmployeeBMPKey(String key) constructor 
*/ public EmployeeBMPKey(String key)  {
  empNo = key;
}
/**
* equals method
* - user must provide a proper implementation for the equal method. The generated 
*   method assumes the key is a String object.
*/ public boolean equals (Object o)  {
  if (o instanceof EmployeeBMPKey) 
    return empNo.equals(((EmployeeBMPKey)o).empNo);
  else
    return false;
}
/**
* hashCode method
* - user must provide a proper implementation for the hashCode method. The generated
*    method assumes the key is a String object.
*/ public int hashCode ()  {
  return empNo.hashCode();


 

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