Use a logger

Use Java logging to log messages and add tracing.

 

About this task

Use WsLevel.DETAIL level and above for messages, and lower levels for trace. The WAS Extension API (the com.ibm.websphere.logging package) contains the WsLevel class.

For messages use

WsLevel.FATAL 
Level.SEVERE 
Level.WARNING 
WsLevel.AUDIT 
Level.INFO 
Level.CONFIG 
WsLevel.DETAIL

For trace use

Level.FINE 
Level.FINER 
Level.FINEST

 

Procedure

1. Use the logp method instead of the log or the logrb method. The logp method accepts parameters for class name and method name. The log and logrb methods will generally try to infer this information, but the performance penalty is prohibitive.

2. Avoid using the logrb method. This method leads to inefficient caching of resource bundles and poor performance.

3. Use the isLoggable method to avoid creating data for a logging call that does not get logged. For example

   if (logger.isLoggable(Level.FINEST)) {
      String s = dumpComponentState();  // some expensive to compute method
      logger.logp(Level.FINEST, className, methodName, "componentX state 
   dump:\n{0}", s);
    }
   

 

Example

The following sample applies to localized messages

// note - generally avoid use of FINE, FINER, FINEST levels for messages to be consistent with
// WebSphere Application Server

String componentName = "com.ibm.websphere.componentX";
String resourceBundleName = "com.ibm.websphere.componentX.Messages";
Logger logger = Logger.getLogger(componentName, resourceBundleName);

// "Convenience" methods - not generally recommended due to lack of class 
/ method names
//   - cannot specify message substitution parameters
//   - cannot  specify class and method names
if (logger.isLoggable(Level.SEVERE))
  logger.severe("MSG_KEY_01");

if (logger.isLoggable(Level.WARNING))
  logger.warning("MSG_KEY_01");

if (logger.isLoggable(Level.INFO))
  logger.info("MSG_KEY_01");

if (logger.isLoggable(Level.CONFIG))
  logger.config("MSG_KEY_01");


// log methods are not generally used due to lack of class and method 
names
//   - enable use of WebSphere Application Server-specific levels
//   - enable use of message substitution parameters
//   - cannot specify class and method names
if (logger.isLoggable(WsLevel.FATAL))
  logger.log(WsLevel.FATAL, "MSG_KEY_01", "parameter 1");

if (logger.isLoggable(Level.SEVERE))
  logger.log(Level.SEVERE, "MSG_KEY_01", "parameter 1");

if (logger.isLoggable(Level.WARNING))
  logger.log(Level.WARNING, "MSG_KEY_01", "parameter 1");

if (logger.isLoggable(WsLevel.AUDIT))
  logger.log(WsLevel.AUDIT, "MSG_KEY_01", "parameter 1");

if (logger.isLoggable(Level.INFO))
  logger.log(Level.INFO, "MSG_KEY_01", "parameter 1");

if (logger.isLoggable(Level.CONFIG))
  logger.log(Level.CONFIG, "MSG_KEY_01", "parameter 1");

if (logger.isLoggable(WsLevel.DETAIL))
  logger.log(WsLevel.DETAIL, "MSG_KEY_01", "parameter 1");


// logp methods are the way to log
//   - enable use of WebSphere Application Server-specific levels
//   - enable use of message substitution parameters
//   - enable use of class and method names
if (logger.isLoggable(WsLevel.FATAL))
  logger.logp(WsLevel.FATAL, className, methodName, "MSG_KEY_01", 
"parameter 1");

if (logger.isLoggable(Level.SEVERE))
  logger.logp(Level.SEVERE, className, methodName, "MSG_KEY_01", 
"parameter 1");

if (logger.isLoggable(Level.WARNING))
  logger.logp(Level.WARNING, className, methodName, "MSG_KEY_01", 
"parameter 1");

if (logger.isLoggable(WsLevel.AUDIT))
  logger.logp(WsLevel.AUDIT, className, methodName, "MSG_KEY_01", 
"parameter 1");

if (logger.isLoggable(Level.INFO))
  logger.logp(Level.INFO, className, methodName, "MSG_KEY_01", 
"parameter 1");

if (logger.isLoggable(Level.CONFIG))
  logger.logp(Level.CONFIG, className, methodName, "MSG_KEY_01", 
"parameter 1");

if (logger.isLoggable(WsLevel.DETAIL))
  logger.logp(WsLevel.DETAIL, className, methodName, "MSG_KEY_01", 
"parameter 1");


// logrb methods are not generally used due to diminished performance 
of switching resource bundles dynamically
//   - enable use of WebSphere Application Server-specific levels
//   - enable use of message substitution parameters
//   - enable use of class and method names
String resourceBundleNameSpecial = 
"com.ibm.websphere.componentX.MessagesSpecial";

if (logger.isLoggable(WsLevel.FATAL))
  logger.logrb(WsLevel.FATAL, className, methodName, resourceBundleNameSpecial, 
"MSG_KEY_01", "parameter 1");

if (logger.isLoggable(Level.SEVERE))
  logger.logrb(Level.SEVERE, className, methodName, resourceBundleNameSpecial, 
"MSG_KEY_01", "parameter 1");

if (logger.isLoggable(Level.WARNING))
  logger.logrb(Level.WARNING, className, methodName, resourceBundleNameSpecial, 
"MSG_KEY_01", "parameter 1");

if (logger.isLoggable(WsLevel.AUDIT))
  logger.logrb(WsLevel.AUDIT, className, methodName, resourceBundleNameSpecial, 
"MSG_KEY_01", "parameter 1");

if (logger.isLoggable(Level.INFO))
  logger.logrb(Level.INFO, className, methodName, resourceBundleNameSpecial, 
"MSG_KEY_01", "parameter 1");

if (logger.isLoggable(Level.CONFIG))
  logger.logrb(Level.CONFIG, className, methodName, resourceBundleNameSpecial, 
"MSG_KEY_01", "parameter 1");

if (logger.isLoggable(WsLevel.DETAIL))
  logger.logrb(WsLevel.DETAIL, className, methodName, resourceBundleNameSpecial, 
"MSG_KEY_01", "parameter 1");

For trace, or content that is not localized, the following sample applies

// note - generally avoid use of FATAL, SEVERE, WARNING, AUDIT,
// INFO, CONFIG, DETAIL levels for trace 
// to be consistent with WebSphere Application Server

String componentName = "com.ibm.websphere.componentX";
Logger logger = Logger.getLogger(componentName);

// Entering / Exiting methods are used for non trivial methods
if (logger.isLoggable(Level.FINER))
  logger.entering(className, methodName);
  
if (logger.isLoggable(Level.FINER))
  logger.entering(className, methodName, "method param1");

if (logger.isLoggable(Level.FINER))
  logger.exiting(className, methodName);

if (logger.isLoggable(Level.FINER))
  logger.exiting(className, methodName, "method result");


// Throwing method is not generally used due to lack of message - use 
logp with a throwable parameter instead
if (logger.isLoggable(Level.FINER))
  logger.throwing(className, methodName, throwable);


// Convenience methods are not generally used due to lack of class 
/ method names
//   - cannot specify message substitution parameters
//   - cannot specify class and method names
if (logger.isLoggable(Level.FINE))
  logger.fine("This is my trace");

if (logger.isLoggable(Level.FINER))
  logger.finer("This is my trace");

if (logger.isLoggable(Level.FINEST))
  logger.finest("This is my trace");


// log methods are not generally used due to lack of class and 
method names
//   - enable use of WebSphere Application Server-specific levels
//   - enable use of message substitution parameters
//   - cannot specify class and method names
if (logger.isLoggable(Level.FINE))
  logger.log(Level.FINE, "This is my trace", "parameter 1");

if (logger.isLoggable(Level.FINER))
  logger.log(Level.FINER, "This is my trace", "parameter 1");

if (logger.isLoggable(Level.FINEST))
  logger.log(Level.FINEST, "This is my trace", "parameter 1");


// logp methods are the recommended way to log
//   - enable use of WebSphere Application Server-specific levels
//   - enable use of message substitution parameters
//   - enable use of class and method names
if (logger.isLoggable(Level.FINE))
  logger.logp(Level.FINE, className, methodName, "This is my trace", 
"parameter 1");

if (logger.isLoggable(Level.FINER))
  logger.logp(Level.FINER, className, methodName, "This is my trace", 
"parameter 1");

if (logger.isLoggable(Level.FINEST))
  logger.logp(Level.FINEST, className, methodName, "This is my trace", 
"parameter 1");


// logrb methods are not applicable for trace logging because no localization 
is involved

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Related tasks
Configuring the logger hierarchy Creating log resource bundles and message files Related reference
Example: Creating custom log handlers with java.util.logging Example: Creating custom filters with java.util.logging Example: Creating custom formatters with java.util.logging Example: Adding custom handlers, filters, and formatters

 

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