Datasource: Cannot load JDBC driver class 'com.mysql.jdbc.Driver'

[Ken Bowen]

Hello,

I'm working on a CENTOS 5 Linux setup.
I'm trying to avoid the pre-loaded tomcat which was installed in
/usr/share/tomcat5.
I downloaded (from apache) and installed tomcat5.5.25 and installed it
in /opt/tomcat5.
I made sure the existing tomcat is not running and I renamed
/usr/share/tomcat5.

I start it (the new tomcat) with /opt/tomcat5/bin/startup.sh and it runs
fine:
Tomcat manager runs and I can start/stop the built-in apps.

I have an app which I developed using tomcat5.5.9 on Windows, and I am
trying to
transfer it to this Linux setting.

I placed my exploded app in webapps. The app wants to use a Mysql
database named sb_data.
The same database as on Windows has been replicated in Mysql in the
Linux setup.
I have the following context.xml in my META-INF folder:

<Context path="/myapp" docBase="myapp"
debug="5" reloadable="true" crossContext="true">
<Resource name="jdbc/sb_data" auth="Container"
type="javax.sql.DataSource"
maxActive="100" maxIdle="30" maxWait="10000"
username="sb_normal" password="********"
driverClassName="com.mysql.jdbc.Driver"

url="jdbc:mysql://localhost:3306/sb_data?autoReconnect=true"/>
</Context>

My application has a registered AppListener in which I establish the
DataSource
in the contextInitialized method and use it to do some initial work with
the database:

System.out.println("MyApp AppListener: ENTER");
....
Context envCtx = (Context) initialContext.lookup("java:comp/env");

String key = "jdbc" + "/" + "sb_data";
DataSource ds = (DataSource)envCtx.lookup(key);
if (ds != null ){
DAOBaseData.setDataSource(ds);
}
....
...CALL to DAOBaseData.getConnection(); HERE
....
System.out.println("MyApp AppListener: EXIT");

The code for getConnection() looks like this:

public Connection getConnection() throws DAOException
{
Connection connection = null;
if (datasource!= null) {
try {
connection = datasource.getConnection();
} catch (SQLException e) {
//TODO: Log this
String message = e.getMessage();
System.out.println("DAOBaseData: "+message);
throw new DAOException(message);
}
}
connCount++;
System.out.println("Connection[data] allocated: #="+connCount);
return connection;
}

This works ok on Windows, but in the Linux setting I get the following
error in
the catalina.out log:

MyApp AppListener: ENTER
DAOBaseData: Cannot load JDBC driver class 'com.mysql.jdbc.Driver'
com.myapp Error: Cannot load JDBC driver class
'com.mysql.jdbc.Driver'
MyApp AppListener: EXIT

I'm using the mysql-connector-java-3.1.14-bin.jar and it is present in
WEB-INF/lib.
I tried copying it to /opt/tomcat5/common/lib , but I still get the same
error.

I'm confused. Why does tomcat on Windows find the JDBC driver, but not
find it on Linux?

Thanks in advance,
Ken Bowen


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[David Smith]

Don't 'copy' the mysql driver from WEB-INF/lib to TOMCAT_HOME/common/lib
-- move it. It cannot be in both places at once. Also be sure the
permissions are set correctly so tomcat can read the jar and be sure
you've restarted tomcat after the move so the classloaders pick it up
properly. I have no idea why it works in Windows at all unless the
Windows install has a copy of it in common/lib already -- which can
cause problems later on if it's also in WEB-INF/lib.

As a side note (and this is becoming a mantra with me) please don't use
?autoReconnect=true in your jdbc url. Instead add the attribute
validationQuery="select 1" in the Resource element. That tells the pool
how to validate the connection and optionally regenerate it before you
borrow.

--David

Post by Ken Bowen
Hello,
I'm working on a CENTOS 5 Linux setup.
I'm trying to avoid the pre-loaded tomcat which was installed in
/usr/share/tomcat5.
I downloaded (from apache) and installed tomcat5.5.25 and installed it
in /opt/tomcat5.
I made sure the existing tomcat is not running and I renamed
/usr/share/tomcat5.
I start it (the new tomcat) with /opt/tomcat5/bin/startup.sh and it
Tomcat manager runs and I can start/stop the built-in apps.
I have an app which I developed using tomcat5.5.9 on Windows, and I am
trying to
transfer it to this Linux setting.
I placed my exploded app in webapps. The app wants to use a Mysql
database named sb_data.
The same database as on Windows has been replicated in Mysql in the
Linux setup.
<Context path="/myapp" docBase="myapp"
debug="5" reloadable="true" crossContext="true">
<Resource name="jdbc/sb_data" auth="Container"
type="javax.sql.DataSource"
maxActive="100" maxIdle="30" maxWait="10000"
username="sb_normal" password="********"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/sb_data?autoReconnect=true"/>
</Context>
My application has a registered AppListener in which I establish the
DataSource
in the contextInitialized method and use it to do some initial work
System.out.println("MyApp AppListener: ENTER");
....
Context envCtx = (Context) initialContext.lookup("java:comp/env");
String key = "jdbc" + "/" + "sb_data";
DataSource ds = (DataSource)envCtx.lookup(key);
if (ds != null ){
DAOBaseData.setDataSource(ds);
}
....
...CALL to DAOBaseData.getConnection(); HERE
....
System.out.println("MyApp AppListener: EXIT");
public Connection getConnection() throws DAOException
{
Connection connection = null;
if (datasource!= null) {
try {
connection = datasource.getConnection();
} catch (SQLException e) {
//TODO: Log this
String message = e.getMessage();
System.out.println("DAOBaseData: "+message);
throw new DAOException(message);
}
}
connCount++;
#="+connCount);
return connection;
}
This works ok on Windows, but in the Linux setting I get the following
error in
MyApp AppListener: ENTER
DAOBaseData: Cannot load JDBC driver class 'com.mysql.jdbc.Driver'
com.myapp Error: Cannot load JDBC driver class
'com.mysql.jdbc.Driver'
MyApp AppListener: EXIT
I'm using the mysql-connector-java-3.1.14-bin.jar and it is present in
WEB-INF/lib.
I tried copying it to /opt/tomcat5/common/lib , but I still get the
same error.
I'm confused. Why does tomcat on Windows find the JDBC driver, but
not find it on Linux?
Thanks in advance,
Ken Bowen
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[Ken Bowen]

David,

Bingo! Right on: Changed all permissions (chown -R tomcat myapp), and
dropped the mysql jar from WEB-INF/lib, and
it all works. Many thanks! I do hate it when I forget simple stuff
like permissions. Moving things from Windows to *nix
always does that to me.
Side note question: Am I correct that the following is the intended xml?:

<Resource name="jdbc/sb_data" auth="Container"
type="javax.sql.DataSource"
maxActive="100" maxIdle="30" maxWait="10000"
validationQuery="select 1"
username="sb_normal" password="********"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/sb_data"/>

Where could I read more about these kinds of details?

Thanks again,
Ken Bowen

Post by David Smith
Don't 'copy' the mysql driver from WEB-INF/lib to
TOMCAT_HOME/common/lib -- move it. It cannot be in both places at
once. Also be sure the permissions are set correctly so tomcat can
read the jar and be sure you've restarted tomcat after the move so the
classloaders pick it up properly. I have no idea why it works in
Windows at all unless the Windows install has a copy of it in
common/lib already -- which can cause problems later on if it's also
in WEB-INF/lib.
As a side note (and this is becoming a mantra with me) please don't
use ?autoReconnect=true in your jdbc url. Instead add the attribute
validationQuery="select 1" in the Resource element. That tells the
pool how to validate the connection and optionally regenerate it
before you borrow.
--David

Post by Ken Bowen
Hello,
I'm working on a CENTOS 5 Linux setup.
I'm trying to avoid the pre-loaded tomcat which was installed in
/usr/share/tomcat5.
I downloaded (from apache) and installed tomcat5.5.25 and installed
it in /opt/tomcat5.
I made sure the existing tomcat is not running and I renamed
/usr/share/tomcat5.
I start it (the new tomcat) with /opt/tomcat5/bin/startup.sh and it
Tomcat manager runs and I can start/stop the built-in apps.
I have an app which I developed using tomcat5.5.9 on Windows, and I
am trying to
transfer it to this Linux setting.
I placed my exploded app in webapps. The app wants to use a Mysql
database named sb_data.
The same database as on Windows has been replicated in Mysql in the
Linux setup.
<Context path="/myapp" docBase="myapp"
debug="5" reloadable="true" crossContext="true">
<Resource name="jdbc/sb_data" auth="Container"
type="javax.sql.DataSource"
maxActive="100" maxIdle="30" maxWait="10000"
username="sb_normal" password="********"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/sb_data?autoReconnect=true"/>
</Context>
My application has a registered AppListener in which I establish the
DataSource
in the contextInitialized method and use it to do some initial work
System.out.println("MyApp AppListener: ENTER");
....
Context envCtx = (Context)
initialContext.lookup("java:comp/env");
String key = "jdbc" + "/" + "sb_data";
DataSource ds = (DataSource)envCtx.lookup(key);
if (ds != null ){
DAOBaseData.setDataSource(ds);
}
....
...CALL to DAOBaseData.getConnection(); HERE
....
System.out.println("MyApp AppListener: EXIT");
public Connection getConnection() throws DAOException
{
Connection connection = null;
if (datasource!= null) {
try {
connection = datasource.getConnection();
} catch (SQLException e) {
//TODO: Log this
String message = e.getMessage();
System.out.println("DAOBaseData: "+message);
throw new DAOException(message);
}
}
connCount++;
#="+connCount);
return connection;
}
This works ok on Windows, but in the Linux setting I get the
following error in
MyApp AppListener: ENTER
DAOBaseData: Cannot load JDBC driver class
'com.mysql.jdbc.Driver'
com.myapp Error: Cannot load JDBC driver class
'com.mysql.jdbc.Driver'
MyApp AppListener: EXIT
I'm using the mysql-connector-java-3.1.14-bin.jar and it is present
in WEB-INF/lib.
I tried copying it to /opt/tomcat5/common/lib , but I still get the
same error.
I'm confused. Why does tomcat on Windows find the JDBC driver, but
not find it on Linux?
Thanks in advance,
Ken Bowen
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[Caldarale, Charles R]

Subject: Re: Datasource: Cannot load JDBC driver class
'com.mysql.jdbc.Driver'
<Resource name="jdbc/sb_data" auth="Container"
type="javax.sql.DataSource"
maxActive="100" maxIdle="30" maxWait="10000"
validationQuery="select 1"
username="sb_normal" password="********"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/sb_data"/>
Where could I read more about these kinds of details?

You've probably already been here:
http://tomcat.apache.org/tomcat-5.5-doc/jndi-resources-howto.html
http://tomcat.apache.org/tomcat-5.5-doc/jndi-datasource-examples-howto.h
tml

Generally, the attributes of a <Resource> element correspond to elements
nested within a <resource-ref> element as described in the servlet spec.
Most of the attributes will be unique to the resource type, so the
Tomcat doc can't provide a great deal of specifics here.

- Chuck


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[David Smith]

Tomcat's database pooling implements a slightly refactored version of
the Commons DBCP project -- packages were renamed to avoid conflicts
should a developer decide to use the Commons DBCP library in their own
app. You can find a complete list of possible attributes for the
Resource definition here:

http://commons.apache.org/dbcp/api-1.2.2/org/apache/commons/dbcp/BasicDataSource.html

Just look at the setters -- remove the word set from the beginning of
the method name and drop the case on the first letter after 'set'. For
example, if you want access setValidationQuery(), you would drop set and
lower case the V for validationQuery="" in your <Resource ../> definition.

--David

Post by Ken Bowen
David,
Bingo! Right on: Changed all permissions (chown -R tomcat myapp),
and dropped the mysql jar from WEB-INF/lib, and
it all works. Many thanks! I do hate it when I forget simple stuff
like permissions. Moving things from Windows to *nix
always does that to me.
<Resource name="jdbc/sb_data" auth="Container"
type="javax.sql.DataSource"
maxActive="100" maxIdle="30" maxWait="10000"
validationQuery="select 1"
username="sb_normal" password="********"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/sb_data"/>
Where could I read more about these kinds of details?
Thanks again,
Ken Bowen

Post by David Smith
Don't 'copy' the mysql driver from WEB-INF/lib to
TOMCAT_HOME/common/lib -- move it. It cannot be in both places at
once. Also be sure the permissions are set correctly so tomcat can
read the jar and be sure you've restarted tomcat after the move so
the classloaders pick it up properly. I have no idea why it works in
Windows at all unless the Windows install has a copy of it in
common/lib already -- which can cause problems later on if it's also
in WEB-INF/lib.
As a side note (and this is becoming a mantra with me) please don't
use ?autoReconnect=true in your jdbc url. Instead add the attribute
validationQuery="select 1" in the Resource element. That tells the
pool how to validate the connection and optionally regenerate it
before you borrow.
--David

Post by Ken Bowen
Hello,
I'm working on a CENTOS 5 Linux setup.
I'm trying to avoid the pre-loaded tomcat which was installed in
/usr/share/tomcat5.
I downloaded (from apache) and installed tomcat5.5.25 and installed
it in /opt/tomcat5.
I made sure the existing tomcat is not running and I renamed
/usr/share/tomcat5.
I start it (the new tomcat) with /opt/tomcat5/bin/startup.sh and it
Tomcat manager runs and I can start/stop the built-in apps.
I have an app which I developed using tomcat5.5.9 on Windows, and I
am trying to
transfer it to this Linux setting.
I placed my exploded app in webapps. The app wants to use a Mysql
database named sb_data.
The same database as on Windows has been replicated in Mysql in the
Linux setup.
<Context path="/myapp" docBase="myapp"
debug="5" reloadable="true" crossContext="true">
<Resource name="jdbc/sb_data" auth="Container"
type="javax.sql.DataSource"
maxActive="100" maxIdle="30" maxWait="10000"
username="sb_normal" password="********"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/sb_data?autoReconnect=true"/>
</Context>
My application has a registered AppListener in which I establish the
DataSource
in the contextInitialized method and use it to do some initial work
System.out.println("MyApp AppListener: ENTER");
....
Context envCtx = (Context)
initialContext.lookup("java:comp/env");
String key = "jdbc" + "/" + "sb_data";
DataSource ds = (DataSource)envCtx.lookup(key);
if (ds != null ){
DAOBaseData.setDataSource(ds);
}
....
...CALL to DAOBaseData.getConnection(); HERE
....
System.out.println("MyApp AppListener: EXIT");
public Connection getConnection() throws DAOException
{
Connection connection = null;
if (datasource!= null) {
try {
connection = datasource.getConnection();
} catch (SQLException e) {
//TODO: Log this
String message = e.getMessage();
System.out.println("DAOBaseData: "+message);
throw new DAOException(message);
}
}
connCount++;
#="+connCount);
return connection;
}
This works ok on Windows, but in the Linux setting I get the
following error in
MyApp AppListener: ENTER
DAOBaseData: Cannot load JDBC driver class
'com.mysql.jdbc.Driver'
com.myapp Error: Cannot load JDBC driver class
'com.mysql.jdbc.Driver'
MyApp AppListener: EXIT
I'm using the mysql-connector-java-3.1.14-bin.jar and it is present
in WEB-INF/lib.
I tried copying it to /opt/tomcat5/common/lib , but I still get the
same error.
I'm confused. Why does tomcat on Windows find the JDBC driver, but
not find it on Linux?
Thanks in advance,
Ken Bowen
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[Caldarale, Charles R]

Subject: Datasource: Cannot load JDBC driver class
'com.mysql.jdbc.Driver'
<Context path="/myapp" docBase="myapp"

Take out the path and docBase attributes - they're not allowed when
using META-INF/context.xml. (This is not likely to solve your problem,
but let's clean up the obvious things first.)

MyApp AppListener: ENTER
DAOBaseData: Cannot load JDBC driver class
'com.mysql.jdbc.Driver'

By intercepting and discarding the original exception, you threw away
much useful information, such as the stack trace. Don't do that.

I tried copying it to /opt/tomcat5/common/lib , but I still
get the same error.

The same jar must not be present in more than one node in a given
classloader branch. So it would be o.k. to /move/ the jar to
common/lib, but you must not have it in both common/lib and WEB-INF/lib.

Why does tomcat on Windows find the JDBC
driver, but not find it on Linux?

Don't know, but the fix the above stuff first (along with what David S
suggested), and let's go from there.

- Chuck


THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY
MATERIAL and is thus for use only by the intended recipient. If you
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[Ken Bowen]

Chuck,

Thanks. As Dave pointed out, my core difficulty was a permissions problem.
BUT: It is running and yet my

META-INF/context.xml

still contains the path and docBase attributes.
Where can I read up on what should be in META-INF/context.xml ??

RE:

By intercepting and discarding the original exception, you threw away
much useful information, such as the stack trace. Don't do that.

Of course, you're right. It's only the presence of my "//TODO: log
this; kill off everything..."
that enables me to claim that I have the right stuff on my list of TODOs.

Thanks again,
Ken Bowen

Post by Caldarale, Charles R

Subject: Datasource: Cannot load JDBC driver class
'com.mysql.jdbc.Driver'
<Context path="/myapp" docBase="myapp"

Take out the path and docBase attributes - they're not allowed when
using META-INF/context.xml. (This is not likely to solve your problem,
but let's clean up the obvious things first.)

MyApp AppListener: ENTER
DAOBaseData: Cannot load JDBC driver class
'com.mysql.jdbc.Driver'

By intercepting and discarding the original exception, you threw away
much useful information, such as the stack trace. Don't do that.

I tried copying it to /opt/tomcat5/common/lib , but I still
get the same error.

The same jar must not be present in more than one node in a given
classloader branch. So it would be o.k. to /move/ the jar to
common/lib, but you must not have it in both common/lib and WEB-INF/lib.

Why does tomcat on Windows find the JDBC
driver, but not find it on Linux?

Don't know, but the fix the above stuff first (along with what David S
suggested), and let's go from there.
- Chuck
THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY
MATERIAL and is thus for use only by the intended recipient. If you
received this in error, please contact the sender and delete the e-mail
and its attachments from all computers.
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[Caldarale, Charles R]

Subject: Re: Datasource: Cannot load JDBC driver class
'com.mysql.jdbc.Driver'
BUT: It is running and yet my META-INF/context.xml
still contains the path and docBase attributes.

In your case, they are probably being ignored, but no one can guarantee
just what the behavior will be in all versions of Tomcat when illegal
attributes are present.

Where can I read up on what should be in META-INF/context.xml ??

http://tomcat.apache.org/tomcat-5.5-doc/config/context.html

- Chuck


THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY
MATERIAL and is thus for use only by the intended recipient. If you
received this in error, please contact the sender and delete the e-mail
and its attachments from all computers.

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