Database Reference
In-Depth Information
String
user
=
"cbuser"
;
String
password
=
"cbpass"
;
Class
.
forName
(
"com.mysql.jdbc.Driver"
).
newInstance
();
return
(
DriverManager
.
getConnection
(
url
,
user
,
password
));
}
// Return an error message as a string
public
static
String
getErrorMessage
(
Exception
e
)
{
StringBuffer
s
=
new
StringBuffer
();
if
(
e
instanceof
SQLException
)
// JDBC-specific exception?
{
// print general message, plus any database-specific message
s
.
append
(
"Error message: "
+
e
.
getMessage
()
+
"\n"
);
s
.
append
(
"Error code: "
+
((
SQLException
)
e
).
getErrorCode
()
+
"\n"
);
}
else
{
s
.
append
(
e
+
"\n"
);
}
return
(
s
.
toString
());
}
// Get the error message and print it to System.err
public
static
void
printErrorMessage
(
Exception
e
)
{
System
.
err
.
println
(
Cookbook
.
getErrorMessage
(
e
));
}
}
The routines within the class are declared using the
static
keyword, which makes them
class methods rather than instance methods. That is done here because the class is used
directly rather than creating an object from it and invoking the methods through the
object.
To use the
Cookbook.java
file, compile it to produce
Cookbook.class
, then install the
class file in a directory that corresponds to the package identifier. This means that
Cookbook.class
should be installed in a directory named
com/kitebird/mcb
(Unix) or
com\kitebird\mcb
(Windows) that is located under some directory named in your
CLASSPATH
setting. For example, if
CLASSPATH
includes
/usr/local/lib/mcb
under Unix,
you can install
Cookbook.class
in the
/usr/local/lib/mcb/com/kitebird/mcb
directory.
(For more information about the
CLASSPATH
variable, see the Java discussion in
Recipe 2.1
.)
To use the
Cookbook
class from within a Java program, import it and invoke the
Cook
book.connect()
method. The following test harness program,
Harness.java
, shows how
to do this:
