JDK Logging

Log4j is widely accepted as a logging component. There is yet another one, the logging component inbuilt in java. This article will discuss about the logging provided by JDK.

Ideal scenario, the entire configuration can be done through the logging.properties file. The logging.properties file should be present in the classpath of the application. In case you want to provide a different properties file, the same can be set using the system property. The command is as shown below

java –Djava.util.logging.config.file=/home/users/mypath/mylogging.properties

The logging.properties file sample is present in the jre/lib folder. This file can be edited to get the necessary logging. The structure of the logging properties file is shown below

#Defines the handlers which can be used by the logger. It can be comma separated. For
# each handler, definition should be provided in the properties file
handlers= java.util.logging.FileHandler, java.util.logging.ConsoleHandler
#Default level of logging in case specific logging level as shown in the last line is not
# mentioned.
.level= INFO
#Details about the filehandler.
java.util.logging.FileHandler.pattern = %h/java%u.log
java.util.logging.FileHandler.limit = 50000
java.util.logging.FileHandler.count = 1
java.util.logging.FileHandler.formatter = java.util.logging.XMLFormatter
#custom logging level
com.xyz.foo.level = SEVERE

By default the logging happens at the package level of the class when you are using the property file for configuring the logger.

The restrictions here are that we can specify only one log file per logging properties file. So in case you need the log to go to multiple files, may be based on the application, it’s not possible through configuration in the properties file. However, you can perform the above requirement by writing a specific logger class.

private void initialize(String name)
{
Handler fileHandler;
try {
fileHandler = new FileHandler(filePath, true);
fileHandler.setFormatter(new MyFormatter());
logger=Logger.getLogger(name);
logger.addHandler(fileHandler);
}
public static MyLogger getInstance(String someName)
{
//add the necessary synchronization blocks
mylogger = new MyLogger();
mylogger.initializer(someName);
return mylogger;
}
//this is sample method. Like this you need to provide implementation for
//all other methods
public void debug(String sourceClass, String sourceMethod, String msg)
{
logger.logp(Level.FINEST,sourceClass,sourceMethod,msg);
}
//in your application code, use it this way
MyLogger logger = MyLogger.getInstance(“namethatidentifiestheloglevel”);
logger.debug(“classname”,”methodname”,”msg”);

In the above code snippet, the log level is not mentioned. The log level can be mentioned in the properties file that is passed as the java.util.logging.config.file property. In this case, the value will be set as

namethatidentifiestheloglevel=SEVERE

There are various levels available, the important ones being SEVERE, INFO, FINE, FINEST, DEBUG etc … Please refer to the sun documentation site as the priority of the log level does matter in the content that gets logged.