Assuming you configured the Resource with a name jdbc/mydb, the
following servlet skeleton can be used .. This is typed out quickly so
check it for errors.
public class DataSourceServlet extends HttpServlet {
private static DataSource dataSource;
public void init() {
try {
Context ctx = new InitialContext();
this.dataSource = (DataSource)
ctx.lookup("java:comp/env/jdbc/mydb");
} catch (Exception e) {
// log the error
}
super.init();
}
public void doGet(HttpServletRequest request, HttpServletResponse
response) throws ServletException {
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse
response) throws ServletException {
Connection connection = null;
try {
connection = dataSource.getConnection();
} catch (SQLException sqlE) {
} finally {
connection.close();
}
}
public void destroy() {
dataSource = null;
}
}
-----Original Message-----
From: Martin Grogan [mailto:[EMAIL PROTECTED]
Sent: 29 November 2005 10:43
To: Jakarta Commons Users List
Subject: Re: [DBCP] Beginner how-to
Hi Allistair,
Thanks for the help. I've downloaded and installed all the relevant
JAR's and edited the server.xml (correctly I hope, I can forward if you
like?).
I've also created a simple database just to test the app.
However, I'm lost when it comes to writing a basic servet that just
opens the connection, executes a query and closes the connection. There
are several (conflicting) resources on the web describing how to do this
(some use JSP's which I don't use). In particular, the init() and
destroy() events seem to be causing me confusion, In my main doGet
method, I have something like :
try
{
Connection connection= ??? need to get a connection from the
pool here
Statement statement=connection.createStatement();
String query="SELECT name,age FROM test";
ResultSet r=statement.execute(query);
while(r.next())
out.println(r.getString(1)+", "+r.getString(2));
statement.close();
}
catch(Exception e) { out.println(e.getMessage()); }
Any ideas?
Thanks,
Martin
Allistair Crossley wrote:
There's a really nice way to get Tomcat to manage your database pool
for you with it's built-in DBCP support. This method is detailed in the
Tomcat pages
http://tomcat.apache.org/tomcat-5.0-doc/jndi-datasource-examples-howto.
h
tml
In a nuthell, you put your database driver JAR into tomcat/common/lib
and take it out of your webapp's WEB-INF/lib. You then declare a
configuration block for a Resource which tells Tomcat to create an
instance of a DBCP database pool. Then, in your servlets you would have
a static member of type DataSource which you would set with a JNDI
lookup for the Resource in the servlet init method. Then, anytime you
needed a connection you call dataSource.getConnection(). You still need
to close your connections however to return them to the pool. Your
servlet destroy method would need to close the dataSource, or at least
set it to null as it will leak being static otherwise on reloads of the
webapp.
Cheers, Allistair
-----Original Message-----
From: Martin Grogan [mailto:[EMAIL PROTECTED]
Sent: 29 November 2005 09:31
To: Jakarta Commons Users List
Subject: Re: [DBCP] Beginner how-to
Yes, using Tomcat 5.0.28,
Allistair Crossley wrote:
Are you using Tomcat?
-----Original Message-----
From: Martin Grogan [mailto:[EMAIL PROTECTED]
Sent: 29 November 2005 09:27
To: Jakarta Commons Users List
Subject: [DBCP] Beginner how-to
Hi all,
I'm a complete beginner with commons DBCP and unsure where to start. I
require connection pooling to increase performance of my web
application.
All elements of my application are servlets (no EJB's, no JSP's) and
for each servlet, I basically do the old-fashioned thing...
1. Open connection to data source (mySQL) 2. Create statement 3.
Execute a pile of queries 4. Close statement 5. Close connection I am
using Tomcat 5.0.28 and mysql-connector-java-3.1.8. We are not using
any dedicated web-server like Apache, just Tomcat.
Can anyone tell my what I need to do to start using connection pooling
in my applications? Maybe some sample servlet code, and server
configuration, JAR's I need, etc.
I'm basically an old ASP programmer that's picked up Java and now am
trying to do things the Java way.
Thanks,
Martin
-----------
Martin Grogan
Keizen Software
[EMAIL PROTECTED]
www.keizensoftware.com
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