What is the SYSTEM PATH that you are referring to ? Is it the JAVA_HOME or the
PATH system variable ?
What is the CLASSPATH just before Tomcat properly starts up ? What is it after
it starts up ? Is the same jar files below -:
bin/bootstrap.jar
bin/tomcat-juli.jar
Correct me if I am wrong that means that whatever dependencies I have in my
project is not added to the SYSTEM CLASSPATH but is instead loaded by TOMCAT.
So if a module searches only the SYSTEM CLASSPATH it won’t be able to find the
dependencies. Am I right ?
Regards
Sreyan Chakravarty
From: Christopher Schultz
Sent: Wednesday, February 18, 2015 8:30 PM
To: Tomcat Users List
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Sreyan,
On 2/18/15 9:25 AM, sreya...@gmail.com wrote:
> I am writing a simple Servlet that uses JDBC to talk to MySQL and
> deploying it in Tomcat. Why do I need to add the line -:
>
> Class.forName("com.mysql.jdbc.Driver");
>
> to load the JDBC driver ? If I don’t do this I get an exception of
> -:
>
> java.sql.SQLException: No suitable driver was found.
>
> Why is it when I use a JDBC connection in Servlets and deploy it
> in Tomcat must the class be loaded dynamically ? Why can’t Tomcat
> do that for me when I have already added it to the build path ?
>
> From Java 6 onwards there is no need for the JDBC Driver to be
> loaded dynamically. So why when using JRE 8 and Tomcat 8 must this
> be done ?
>
> Cant it be loaded automatically like for normal apps ? It sure
> would be a lot more cleaner code.
My guess is that DriverManager only searches the system CLASSPATH
which only contains the following JAR files when launching Tomcat
using the standard scripts:
bin/bootstrap.jar
bin/tomcat-juli.jar
The bootstrap class then configures a new ClassLoader (including
lib/*.jar) for the Tomcat server and Tomcat properly launches using
/that/.
I think your JDBC driver simply isn't visible to DriverManager's
auto-loading. But when you call Class.forName, the driver registers
itself with DriverManager, which is okay to do if DriverManager didn't
know about your driver.
- -chris
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