Re: Problem with Java-SQL connection, postgresql.conf file

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Christopher Bruhn schrieb:
> Hallo,
>
> I want to establish a connection to an SQL Database from a
> Java Applet which is situated on the same server. I used the
> interface postgresql-8.2dev-503.jdbc3.jar. I use
> NetBeans IDE 5.0 (Sum Microsystems) for the development of
> Java Code. I copied postgresql-8.2dev-503.jdbc3.jar into the
> build/classes folder of the project containing the Applet
> and made it accessible for Compile and Run as a Library of
> the project
> (Project -> Properties -> Libraries -> added
> postgresql-8.2dev-503.jdbc3.jar to Run and Compile). I also
> added postgresql-8.2dev-503.jdbc3.jar as a driver
> (Runtime -> Databases -> Drivers -> Add Driver -> PostgreSQL
> (v7.0 and later) is accessible).
> Moreover I unpacked the jar file into the build/classes folder
> and uploaded all files contained in the build folder to the
> server (SERVER_SOFTWARE: Apache/2.0.54 (Fedora)).
>
> I used essentially the following Java code (Java 1.5.0_07)...
>
> ////////////////////////////
> import java.applet.Applet;
> import java.sql.*;
>
> public class O17 extends Applet implements Runnable {
> private Thread worker;
>
> public synchronized void start() {
> if (worker == null) {
> worker = new Thread(this);
> worker.start();
> }
> }
>
> public void run() {
> String url = "jdbc:postgresql://localhost/<DB>";
>
> try {
> Class.forName("org.postgresql.Driver");
> } catch(Exception ex) {
> setError("Can't find Database driver class: " + ex);
> return;
> }
>
> try {
> Connection con = DriverManager.getConnection(url,
> rightuser, rightpassword);
> Statement stmt = con.createStatement();
> stmt.executeUpdate(createTableCoffees);
>
> stmt.close();
> con.close();
>
> } catch(SQLException ex) {
> setError("SQLException: " + ex);
> }
> }
> }
> ////////////////////////////
>
> ... and different variations of the url which produced the following
> error codes:
>
> jdbc:postgresql://localhost:5432/<DB>
> jdbc:postgresql://localhost/<DB>
> jdbc:postgresql://<DB>
> ->org.postgresql.util.PSQLException: Etwas Ungewöhnliches ist passiert,
> das den Treiber fehlschlagen liess. Bitte teilen Sie diesen Fehler mit.
>
> jdbc:postgresql://molekuelkueche.de/usr_web593_1
> ->org.postgresql.util.PSQLException: Der Verbindungsversuch schlug fehl.
> (SERVER_NAME = www.molekuelkueche.de <http://www.molekuelkueche.de>)
>
> Moreover I searched for the postgresql.conf file but I could not find it
> among the files extracted from postgresql-8.2dev-503.jdbc3.jar.
>
> Can you tell me if I use the Driver in a wrong way, where I can find
> the postgresql.conf file and if I need to make changes in this file?
>

It looks as if your database is not correct configured for a connection
over tcp/ip. The file postgresql.conf is in the directory of the
database. There you have to comment out the line with the
'listen_adresses' and give it the correct parameters. If that looks
correct you have to configure the access to the database in the file
pg_hba.conf in the same directory. Consider the handbook for the correct
parameters.

Regards,
Roland.

- --
Dipl.-Phys. Roland Walter
mailto: roland (dot) walter (dot) rwa (at) gmx (dot) net
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