JDBC logging using java.util.logging

Contributed by Eric McCormack

The EnterpriseDB JDBC Driver supports the use of logging (or tracing) to help resolve issues with the JDBC Driver when is used in your application.

The JDBC Driver uses the logging APIs of java.util.logging (part of Java since JDK 1.4), which makes it a good choice for the driver since it doesn't add any external dependency for a logging framework. java.util.logging is a very rich and powerful tool, it's beyond the scope of this blog to explain or use its full potential, for that please refer to Java Logging Overview.

This logging support was added since version 42.1.4.1 of the EnterpriseDB JDBC Driver, while previous versions use a custom mechanism to enable logging that it is replaced by the use of java.util.logging in current versions, the old mechanism is no longer available.

Configuration

The Logging APIs offer both static and dynamic configuration control. Static control enables field service staff to set up a particular configuration and then re-launch the application with the new logging settings. Dynamic control allows for updates to the logging configuration within a currently running program.

As part of the support of a logging framework in the JDBC Driver, there was a need to facilitate the enabling of the Logger using connection properties, which uses a static control to enable the tracing in the driver. Keep in mind that if you use an Application Server (Tomcat, JBoss, WildFly, etc.) you should use the facilities provided by the application server to enable the logging, as most Application Servers use dynamic configuration control which makes easy to enable/disable logging at runtime.

The root logger used by the JDBC driver is com.edb.

Enable logging by using connection properties

The driver provides a facility to enable logging using connection properties, it's not as feature rich as using a logging.properties file, so it should be used when you are really debugging the driver.

The properties are loggerLevel and loggerFile:

loggerLevel: Logger level of the driver. Allowed values: OFF, DEBUG or TRACE.

This option enables the java.util.logging.Logger Level of the driver based on the following mapping:

As noted, there are no other levels supported using this method, and internally the driver Logger levels should not (for the most part) use others levels as the intention is to debug the driver and don't interfere with higher levels when some applications may enable them globally.

loggerFile: File name output of the Logger.

If set, the Logger will use a java.util.logging.FileHandler to write to a specified file. If the parameter is not set or the file can't be created the willjava.util.logging.ConsoleHandler be used instead.

This parameter should be used together with loggerLevel.

The following is an example of how to use connection properties to enable logging:

jdbc:edb://localhost:5432/mydb?loggerLevel=DEBUG
jdbc:edb://localhost:5432/mydb?loggerLevel=TRACE&loggerFile=edbjdbc.log

Enable logging by using logging.properties file

The default Java logging framework stores its configuration in a file called logging.properties. Settings are stored per line using a dot notation format. Java installs a global configuration file in the lib folder of the Java installation directory, although you can use a separate configuration file by specifying the java.util.logging.config.file property when starting a Java program. logging.properties files can also be created and stored with individual projects.

The following is an example of settings that you can make in the logging.properties:

# Specify the handler, the handlers will be installed during VM startup.
handlers= java.util.logging.FileHandler

# Default global logging level.
.level= OFF

# default file output is in user's home directory.
java.util.logging.FileHandler.pattern = %h/edbjdbc%u.log
java.util.logging.FileHandler.limit = 5000000
java.util.logging.FileHandler.count = 20
java.util.logging.FileHandler.formatter = java.util.logging.SimpleFormatter
java.util.logging.FileHandler.level = FINEST

java.util.logging.SimpleFormatter.format=%1$tY-%1$tm-%1$td %1$tH:%1$tM:%1$tS %4$s %2$s %5$s%6$s%n

# Facility specific properties.
com.edb.level=FINEST

And when you run your application you pass the system property: java -jar -Djava.util.logging.config.file=logging.properties run.jar