Re: jdbc works in java app, fails in servlet: "no suitable jdbc found" - Mailing list pgsql-jdbc

Thank you for the reply!

You need to preload the PostgreSQL driver...

Being new to this, I find myself second-guessing words as simple as "preload". The servlet "NearbyTest" has a constructor and a single method "doGet" which is invoked by an HTML page. As the first working statement in the "doGet" method (at this point everything else is commented out), I tried using the recommended statements. Both of them elicited the same error message:

try {
//  Class.forName("org.postgresql.Driver");
  this.getClass().getClassLoader().loadClass("org.postgresql.Driver");
} catch (ClassNotFoundException e1) {
  e1.printStackTrace();
}

java.lang.ClassNotFoundException: org.postgresql.Driver
  at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.
java:1516)
  at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.
java:1361)
  at nearbyGPS.NearByTest.doGet(NearByTest.java:59)
  ...

---where nearbyGPS is the package and NearByTest is the servlet class.

As an experiment I tried importing the Driver class directly, e.g.:

import org.postgresql.*;
--and the form--
import org.postgresql.Driver;

These import statements both compile without complaint. But the same error occurs. I'm afraid that there must be something rather fundamental that I am missing. Is there another stage (prior to the servlet's "doGet") at which the "preloading" should occur?

I just tried placing the recommended connection code in the constructor, and get exactly the same error message and stack trace.

Eclipse has the option of right-clicking the project and selecting "Configure Build Path". On this project, the PostgreSQL JDBC driver is listed alongside the JRE and Apache libraries.

The stack trace indicates code that is part of Apache. Is there possibly something that has to be configured in Apache that is missing?

Many, many thanks in advance.

++++++++++++++++++++++++++++++++++++++++++++++++++++

On 02/06/10 12:56, philfrei@aol.com wrote:

Hi - I am new to Postgresql (and Eclipse and Tomcat--triple

threat),and

would have posted this question in the general section, but thought

it

might be more appropriate here since it concerns the JDCB.

I have successfully installed and run some example programs from Core
Java II by Horstmann. I wish to connect to a database from a Java
Servlet, and tried using the same code and properties as is being

used

in a Java application program (which successfully connects to the

same

db), but am getting the following error when executing the
DriverManager.getConnection(url, username, password) code:

java.sql.SQLException: No suitable driver found for

jdbc:postgresql:gpsdata

The JRE's JDBC is complaining that it doesn't know what to do with URLs
of type 'jdbc:postgresql'. This means that the PostgreSQL JDBC driver
hasn't been loaded.

You need to preload the PostgreSQL driver, org.postgresql.Driver , to
register it with JDBC so that JDBC knows to use it for 'postgresql'

URLs.

Load the JDBC driver with with 'Class.forName' if it's on the System
classpath, or (preferably) the classloader that loaded your servelet.

Is a different driver needed in the "Servlet" context?

No, but you might need to load it differently if your container doesn't
use the system classloader.

You can use the classloader that loaded the currently running object

with:

 this.getClass().getClassLoader().loadClass('org.postgresql.Driver');

--
Craig Ringer

Tech-related writing: http://soapyfrogs.blogspot.com/

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