Jonathan Baker wrote:
> Unfortunately, no. I just wasn't proofreading my mail. The correct code
> should read:
>
> try {
> InitialContext ic = new InitialContext();
> DataSource ds = (DataSource) ic.lookup(...);
> Connection c = ds.getConnection();
>
> try {
> ...
>
> The point I was trying to make is that using try/finally blocks can keep
> your connections from being stranded. It also guarantees your statement
> objects will close, freeing up memory even if there was an exception thrown
> during processing.
>
> I hope that clears things up!
>
> Jonathan Baker
> Internet Applications Division
> Sybase, Inc.
> [...]
Hi :-) Thanks very much for your email! and sorry for bothering you with
another question:
0
I am trying to develop a simple DBConnection pool, I want to use it in:
* my Servlet class which is put in the Servlet container of my EJB container
* my Session Bean
the following is my code, if you have time, can you give me some direction
about it ? -> tell me if my code is right or not? Thanks!
1 my code
[a] ******************** the simple DBConnection pool *********************
public class outsideDBCPHoder implements java.io.Serializable {
private static outsideDBCPHoder onlyOneInstance;
private java.util.Vector pool=new java.util.Vector();
private outsideDBCPHoder() {}
public static synchronized outsideDBCPHoder getOnlyOneInstance() {
if (onlyOneInstance == null) {
onlyOneInstance = new outsideDBCPHoder();
}
return onlyOneInstance;
}
public synchronized java.sql.Connection getDBConnection() {
java.sql.Connection con = null;
if ( pool.isEmpty() ) {
con = ...; //make a new DBConnection
} else {
con = (java.sql.Connection) pool.elementAt(0);
pool.removeElementAt(0);
}
return con;
}
public synchronized void putbackDBConnection( java.sql.Connection con ) {
if (pool.size() < 8) { // 8 is the MAX number of my pool, it can be any
value(10, 100...)
pool.addElement(con);
}else{
... //close this con
con=null;
}
return;
}
public synchronized void closeAllDBConnection() {
String con=null;
if ( !pool.isEmpty() ) {
con=(java.sql.Connection)pool.elementAt(0);
...// cole the con
con=null;
pool.removeElementAt(0);
}
}
protected synchronized void finalize(){
closeAllDBConnection();
}
}
[b] ********how to use this simple DBConnection pool in Servlet class********
public class servlet_outsideDBCPHoder extends HttpServlet {
private static outsideDBCPHoder myDBCP
=outsideDBCPHoder.getOnlyOneInstance();
//init ...
_service/doGet/doPost{
java.sql.Connection con= myDBCP.getDBConnection();
...// use con
myDBCP.putbackDBConnection(con);
}
protected void finalize(){
myDBCP.closeAllDBConnection();
}
}
[c] outsideDBCPHoder is a *SingleTonBean* ->
* the reason for making it as a SingleTon is:
try to avoid the problem led by loading/unloading MyServlet several
times, but perhaps it is not necessary, I am not sure.
* the reason for that make it Serializable is:
from the emails in Servlet-List, bean class will be loaded by
the same ClassLoader, I also don't know if it is nessary.
If you have time, please give me some directions,
Thanks very much && anyway && in advance! :-)
Bo
Nov.17, 2000
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