the singleton is just a concrete java class that ensures only one instance
can ever be instantiated. i ensure this via this method:
public static synchronized ConnectionPool getInstance()
throws SQLException
{
if (instance == null)
{
instance = new ConnectionPool(driver,url,username,password,
initialConnections,maxConnections,
waitIfBusy);
}
return instance;
}
this class is no different than any other class. the important part of
making the connection pool available to the rest of your application is
storing the reference to the pool in the servlet context. once you've done
this, and assuming your connectionbroker class is a servlet with access to
the servlet context containing the connection pool reference, you can call
getConnection() and releaseConnection() on the servlet class, which in turn
gets and returns connections from/to the connection pool.
----Original Message Follows----
From: "Valeriy Molyakov" <[EMAIL PROTECTED]>
Reply-To: [EMAIL PROTECTED]
To: <[EMAIL PROTECTED]>
Subject: Re: Database connection pool scope
Date: Mon, 26 Feb 2001 18:12:15 +0200
Two questions:
What is the singleton?
Where it is possible to receive such class ?
----- Original Message -----
From: "Jon Crater" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, February 26, 2001 5:17 PM
Subject: RE: Database connection pool scope
> i use a connection pool in tomcat 3.2.1. i have a servlet,
> ConnectionBroker.java, which, in its init() method checks for the
existence
> of the connection pool. if the connection pool is null, it creates an
> instance of it and binds it to the servlet context. then other classes
can
> call this class' static getConnection() and releaseConnection() methods
> without having to worry about whether they extend HttpServlet. the init
> method looks like this:
>
> public void init()
> {
> ServletContext ctx = getServletContext();
> jdbcPool = (ConnectionPool)ctx.getAttribute("jdbcPool");
>
> if (jdbcPool == null)
> {
> try
> {
> jdbcPool = ConnectionPool.getInstance();
> ctx.setAttribute("jdbcPool", jdbcPool);
> }
> catch (SQLException sqle)
> {
> debug("SQLException caught: " + sqle.getMessage());
> }
> }
> }
>
> the getConnection() method looks like this:
>
> public static Connection getConnection()
> throws SQLException
> {
> return jdbcPool.getConnection();
> }
>
> i then have a singleton ConnectionPool class which creates and manages
jdbc
> connections.
>
> -jc
>
>
> ----Original Message Follows----
> From: Randy Layman <[EMAIL PROTECTED]>
> Reply-To: [EMAIL PROTECTED]
> To: [EMAIL PROTECTED]
> Subject: RE: Database connection pool scope
> Date: Mon, 26 Feb 2001 07:58:53 -0500
>
>
> First of all, there are several connection pools avaiable, so you
> might want to look at those before you decide that re-inventing the wheel
is
> a good thing.
>
> Second, most connection pools work by using static classes. Your
> code would look something like:
>
> Connection conn = ConnectionPool.getConnection();
>
> and the ConnectionPool would look something like:
>
> public static Connection getConnection()
>
>
> Randy
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
> Sent: Monday, February 26, 2001 5:17 AM
> To: [EMAIL PROTECTED]
> Subject: Database connection pool scope
>
>
> Hello everybody,
>
> I am pretty new to Tomcat, but previously developed applications for
other
> Java application servers (mostly Bea Weblogic). We want to set up a
> database connection pool to enhance performance, but we are making
database
> connections using our class libraries; not directly from servlets /
JSPs...
> To use a pool inside a JSP I would simply create an application object or
a
> JavaBean and use it. But inside a class; I cannot use Tomcat's
application
> scope. In Weblogic, there is a special "workspace" class, which
> instantiates with the server startup and is available to other classes in
> the application (this is very similar to the application object in JSPs -
> but you can use it everywhere). Is there a counterpart in Tomcat? If not,
> how can I implement a connection pool which is available to the business
> classes that I wrote.
>
> Thanks in advance.
> Selcuk Ayguney
>
>
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