closing connection, why must be done?
On a book i read the following example (at the bottom). I imported it in a jar than run with jboss.
The error on interroga(String str) method is:
ON CLIENT
java.sql.SQLException: Connection handle has been closed and is unusable
ON SERVER
[CachedConnectionManager] Closing a connection for you. Please close them yourself: org.jboss.resource.adapter.jdbc.WrappedConnection@594680
The problem is the that is in the apriConnessione() i got a call for make a db connection. This one is activated fist from ejbActivate(); then jboss close automatically connection without a ejbPassivate(). Then i enter in Interroga() method and the connection is no more avaible giving me exception.
I read the FAQ , expecially http://www.jboss.org/wiki/Wiki.jsp?page=WhatDoesTheMessageDoYourOwnHousekeepingMean
and so i correct the exercise putting alla connection statemente in the method interroga():
con = ds.getConnection(); & if(rs != null) rs.close(); if(ps != null) ps.close(); if(con != null) con.close();
In this case the program has no error.
BUT
I do not understand the beaviour of jboss because i studied that in ejbPassivate / ejbActivate i must close connections; not in every method!
Reading the FAQ i understand that i must open & close connection in every method.
Can you explain me why? .. or what i misunderstand :)
thankyou, Bye
package StatefulDb;
import javax.ejb.*;
import java.sql.*;
import javax.sql.*;
import javax.naming.*;
public class StatefulJdbcBean implements SessionBean {
private SessionContext ctx;
private DataSource ds = null;
transient private Connection con = null;
transient private PreparedStatement ps = null;
transient private ResultSet rs = null;
private String cognome = null;
private String nome = null;
private String p_iva = null;
private String cod_fiscale = null;
public StatefulJdbcBean() {}
public void setSessionContext(SessionContext c) {
ctx=c;
}
public void ejbCreate(){
InitialContext initCtx = null;
try {
initCtx = new InitialContext();
ds = (javax.sql.DataSource)
initCtx.lookup("java:comp/env/jdbc/DSCliente");
} catch(NamingException ne) {
System.out.println("UNABLE to get a connection from
[java:comp/env/jdbc/DSCliente]");
throw new EJBException("Unable to get a connection
from [java:comp/env/jdbc/DSCliente]");
} finally {
try {
if(initCtx != null) initCtx.close();
} catch(NamingException ne) {
System.out.println("Error closing context: " + ne);
throw new EJBException("Error closing context " + ne);
}
}
}
public void ejbRemove(){
try{
chiudiConnessione();
}catch(SQLException ex){
ex.printStackTrace();
throw new EJBException("Error closing resources " + ex);
}
}
public void ejbPassivate(){
try{
chiudiConnessione();
}catch(SQLException ex){
ex.printStackTrace();
throw new EJBException("Error closing resources " + ex);
}
}
public void ejbActivate(){
try{
apriConnessione();
}catch(SQLException ex){
ex.printStackTrace();
throw new EJBException("Error in opening a connection " + ex);
}
}
public void apriConnessione() throws SQLException {
con = ds.getConnection();
}
public void chiudiConnessione() throws SQLException {
if(rs != null) rs.close();
if(ps != null) ps.close();
if(con != null) con.close();
}
public void interroga(String str) throws SQLException {
ps = con.prepareStatement(str);
rs = ps.executeQuery();
if (rs.next()){
cognome=rs.getString("COGNOME");
nome=rs.getString("NOME");
p_iva=rs.getString("P_IVA");
cod_fiscale=rs.getString("COD_FISCALE");
}
}
public String getCognome(){
return cognome;
}
public String getNome(){
return nome;
}
public String getP_iva(){
return p_iva;
}
public String getCod_fiscale(){
return cod_fiscale;
}
}
