Hi,
Hello,
I'd like to know how to implement connection pooling in my
application.
This is what I had done so far. Pls let me know what I need to change
to use the pooling mechanism.
1. I created a singleton class: DatabaseOperations.
2. It has an Connection instance: conn.
3. During initialization, it gets connection as follows:
DataSource ds = (DataSource)
ctx.lookup("java:comp/env/jdbc/mySQLDatabase");
conn = ds.getConnection();
4. I have several public operations method (e.g selectOperations(...),
insertOperations(...)).
5. Let's say I'd like to perform a select statement. Inside my
selectOperations(...):
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(...);
<process the result>
In my finally block, I have:
rslt.close();
stmt.close();
Questions:
1. Do I need to code any different to enable the connection pooling?
NO
2. When I called ds.getConnection(), does it opens up several
connections for pooling
or just one connection?
Depends on how you have it configured. maxActive and maxIdle settings for the
resource.
3. Do I need to close conn every time as well? Since conn is an
instance,
how does it gets connection everytime an operation method is
called? (insert, select, update).
Yes, you have to close the connection each time, which returns the connection
to the pool for
other processes to use.
I have the following methods in my generic DataBase Operations class.
static public Connection getConnection() throws SQLException {
Connection conn = null;
try{
conn = ds.getConnection();
}
catch (Exception e) {
e.printStackTrace();
}
return conn;
}
static public void releaseConnection(Connection con){
try{
if (con != null)
con.close();
}
catch (Exception e) {
e.printStackTrace();
}
}
which get and close my connections for me. So, when I am in the selectOperations(..) I
call the getConnetion()
to get a connection and in the finally block I call the releaseConnection() method.
Hope this helps.
Kal.
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