A Guide to Logging in JHOVE

Controlling JHOVE Application Logging Levels

To change the logging level when you run the code, you can either add something like this to the config file:

<jhoveConfig version="1.0"

Where the log level honours the following values:

<xs:enumeration value="OFF"/>
<xs:enumeration value="SEVERE"/>
<xs:enumeration value="WARNING"/>
<xs:enumeration value="INFO"/>
<xs:enumeration value="CONFIG"/>
<xs:enumeration value="FINE"/>
<xs:enumeration value="FINER"/>
<xs:enumeration value="FINEST"/>
<xs:enumeration value="ALL"/>

So setting <logLevel>ALL</logLevel> shows all message, where <logLevel>WARNING</logLevel> would display WARNING and SEVERE log messages only. JHOVE’s default settings show only SEVERE messages.

You can also change the logging level by passing a -l param with the same level values, e.g. jhove --version -l ALL would set the log level to ALL and overrides the config setting.

Logging from Java Code

If you’re new to Java or Java logging please read the official guide to Java logging. Please use native Java logging rather than introduce a dependency. The correct import and logger initialization look like this:

import java.util.logging.Level;
import java.util.logging.Logger;

public class SomeClass {
    /** Logger for this class. */
    private static final Logger logger = Logger.getLogger(SomeClass.class.getCanonicalName());

The logger can then be used to log messages at a defined level. These levels range from Level.FINEST (detailed debug) to Level.SEVERE for unrecoverable errors. You can log messages at your chosen level using:

logger.log(Level.FINE, "message")
logger.log(Level.FINE, "message", exception)

The second example will also log the results of the accompanying exception.