Thread: Still baffled by a CONNECTion problem
It appears my first appeal for help wasn�t clear enough.
I want to connect my Java Application running on Windows 2000 to my
postgresql database.
From what I understand and have read there are AT LEAST 2 things I need to
do.
(1) Have the application load the relevant JDBC driver and
(2) Make a connection.
With respect to (1), despite numerous attempts I have been unable to resolve
the ClassNotFound exception.
I have set the CLASSPATH environment variable as follows:
%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;C:\PROGRA~1\ULTRAE~1;C:\Program
Files\Java\jdk1.5.0_04\bin;C:\Program Files\PostgreSQL\8.0\jdbc
I have written some test code in Java to load the Driver, as follows:
public void displayClasspath()
{
String driverPath = "C:\\Program Files\\PostgreSQL\\8.0\\jdbc";
String classpath = System.getProperty("java.class.path");
_displayTextArea.append("Classpath = " + classpath + "\n");
classpath = classpath + ";" + driverPath +
"\\postgresql-8.0-311.jdbc3.jar";
System.setProperty("java.class.path", classpath);
_displayTextArea.append("Classpath = " + classpath + "\n");
System.setProperty("jdbc.drivers", driverPath);
String drivers = System.getProperty("jdbc.drivers");
_displayTextArea.append("Drivers = " + drivers + "\n");
// 1. Load the jdbc.odbc database driver class
try
{
File driverDir = new File(driverPath);
if ( driverDir.isDirectory() )
_displayTextArea.append("DriverDir is a directory \n");
else
_displayTextArea.append("DriverDir is NOT a directory \n");
File dFile = new File(driverPath +
"\\org\\postgresql\\Driver.class");
if ( dFile.isFile() )
_displayTextArea.append("Driver is a file \n");
else
_displayTextArea.append("Driver is NOT a file \n");
String driver = "org.postgresql.Driver";
driverPath = driverPath + "\\" + driver;
Class.forName(driver);
}
catch (ClassNotFoundException cnfe)
{
System.out.println("ClassNotFoundException.");
}
}
The output from this code is as follows:
Classpath = C:\Eclipse\Workspace\Test
Classpath = C:\Eclipse\Workspace\Test;C:\Program
Files\PostgreSQL\8.0\jdbc\postgresql-8.0-311.jdbc3.jar
Drivers = C:\Program Files\PostgreSQL\8.0\jdbc
DriverDir is a directory
Driver is a file
So:
- for some unknown reason my Eclipse editor has reset my CLASSPATH
- but despite this I am able to programmatically adjust the CLASSPATH
property to suit
- Java recognized the directory where I have installed the JAR file as a
valid directory and is able to locate the relevant driver file
WHY WON�T IT LOAD the DRIVER?????
With respect to (2) creating a connection.
From what I have read I need to set the PostMaster to run with a �-I� flag
to enable TCP/IP communication.
However the Postmaster is started somewhere in the boot sequence, and I
don�t know how to adjust it�s startup.
HOW DO I DO THIS?
IS THERE SOMETHING ELSE I NEED TO DO???
I think I can work out the connection parameters and make the connection IF
I CAN RESOLVE THESE QUESTIONS.
Yours Sincerely
Peter Cook
_________________________________________________________________
REALESTATE: biggest buy/rent/share listings
http://ninemsn.realestate.com.au
Peter,
1) You need to specify the jar in the classpath, not just the directory.
ie CLASSPATH=...;C:\Program Files\PostgreSQL\8.0\jdbc
\postgresql-8.0-311.jdbc3.jar
2) locate the postgresql.conf file and edit this to enable a
connection to be made, I believe you need to change listen_address to
'*'
Dave
On 8-Oct-05, at 3:34 AM, Peter Cook wrote:
> It appears my first appeal for help wasn’t clear enough.
>
> I want to connect my Java Application running on Windows 2000 to my
> postgresql database.
>
> From what I understand and have read there are AT LEAST 2 things I
> need to do.
>
> (1) Have the application load the relevant JDBC driver and
>
> (2) Make a connection.
>
> With respect to (1), despite numerous attempts I have been unable
> to resolve the ClassNotFound exception.
>
> I have set the CLASSPATH environment variable as follows:
> %SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;C:
> \PROGRA~1\ULTRAE~1;C:\Program Files\Java\jdk1.5.0_04\bin;C:\Program
> Files\PostgreSQL\8.0\jdbc
>
> I have written some test code in Java to load the Driver, as follows:
> public void displayClasspath()
> {
> String driverPath = "C:\\Program Files\\PostgreSQL\\8.0\
> \jdbc";
> String classpath = System.getProperty("java.class.path");
> _displayTextArea.append("Classpath = " + classpath + "\n");
>
> classpath = classpath + ";" + driverPath + "\
> \postgresql-8.0-311.jdbc3.jar";
> System.setProperty("java.class.path", classpath);
> _displayTextArea.append("Classpath = " + classpath + "\n");
>
> System.setProperty("jdbc.drivers", driverPath);
> String drivers = System.getProperty("jdbc.drivers");
> _displayTextArea.append("Drivers = " + drivers + "\n");
>
> // 1. Load the jdbc.odbc database driver class
> try
> {
> File driverDir = new File(driverPath);
> if ( driverDir.isDirectory() )
> _displayTextArea.append("DriverDir is a directory \n");
> else
> _displayTextArea.append("DriverDir is NOT a
> directory \n");
>
> File dFile = new File(driverPath + "\\org\\postgresql\
> \Driver.class");
> if ( dFile.isFile() )
> _displayTextArea.append("Driver is a file \n");
> else
> _displayTextArea.append("Driver is NOT a file \n");
>
> String driver = "org.postgresql.Driver";
> driverPath = driverPath + "\\" + driver;
>
> Class.forName(driver);
> }
> catch (ClassNotFoundException cnfe)
> {
> System.out.println("ClassNotFoundException.");
> }
> }
>
> The output from this code is as follows:
> Classpath = C:\Eclipse\Workspace\Test
> Classpath = C:\Eclipse\Workspace\Test;C:\Program Files\PostgreSQL
> \8.0\jdbc\postgresql-8.0-311.jdbc3.jar
> Drivers = C:\Program Files\PostgreSQL\8.0\jdbc
> DriverDir is a directory
> Driver is a file
>
> So:
> - for some unknown reason my Eclipse editor has reset my CLASSPATH
> - but despite this I am able to programmatically adjust the
> CLASSPATH property to suit
> - Java recognized the directory where I have installed the JAR file
> as a valid directory and is able to locate the relevant driver file
>
> WHY WON’T IT LOAD the DRIVER?????
>
>
> With respect to (2) creating a connection.
> From what I have read I need to set the PostMaster to run with a “-
> I” flag to enable TCP/IP communication.
> However the Postmaster is started somewhere in the boot sequence,
> and I don’t know how to adjust it’s startup.
>
> HOW DO I DO THIS?
>
>
> IS THERE SOMETHING ELSE I NEED TO DO???
>
> I think I can work out the connection parameters and make the
> connection IF I CAN RESOLVE THESE QUESTIONS.
>
> Yours Sincerely
>
> Peter Cook
>
> _________________________________________________________________
> REALESTATE: biggest buy/rent/share listings http://
> ninemsn.realestate.com.au
>
>
> ---------------------------(end of
> broadcast)---------------------------
> TIP 6: explain analyze is your friend
>
>
Peter Cook wrote:
> catch (ClassNotFoundException cnfe)
> {
> System.out.println("ClassNotFoundException.");
> }
> }
>
> The output from this code is as follows:
> Classpath = C:\Eclipse\Workspace\Test
> Classpath = C:\Eclipse\Workspace\Test;C:\Program
> Files\PostgreSQL\8.0\jdbc\postgresql-8.0-311.jdbc3.jar
> Drivers = C:\Program Files\PostgreSQL\8.0\jdbc
> DriverDir is a directory
> Driver is a file
>
> So:
> - for some unknown reason my Eclipse editor has reset my CLASSPATH
> - but despite this I am able to programmatically adjust the CLASSPATH
> property to suit
> - Java recognized the directory where I have installed the JAR file as a
> valid directory and is able to locate the relevant driver file
>
> WHY WON’T IT LOAD the DRIVER?????
Your sample output did not include the ClassNotFoundException output, so
it seems to me that the driver actually loaded fine?
-O