Receiving Trace and Debug Information

The com.sun.jdmk.TraceManager class uses the notification mechanism to distribute the information. You must add a notification listener to receive information (see example Example 4–1). There are two ways to receive trace information:

• Adding a notification listener with a filter in the code. It is possible to have more than one notification listener but with different filters. With TraceFilter, you can specify the type and level of information you want to receive. See Example 4–3 and Example 4–2.

• Specifying system properties in the command to start the Java interpreter when you run a class. In this case, the code of the class must include a call to the TraceManager method. When the TraceManager method is called, all the previously enabled trace and debug information are disabled. Only the properties currently defined when the method is called are enabled.

Example 4–1 Creating a Notification Listener

// Create a listener and save all info to the file /tmp/trace 
TraceListener listener = new TraceListener("/tmp/trace"); 

Example 4–2 Creating a Trace Filter

// create a trace filter with LEVEL_DEBUG and INFO_ALL/
TraceFilter filter = new TraceFilter(Trace.LEVEL_DEBUG, Trace.INFO_ALL);

Example 4–3 Adding the Notification Listener to the class

// add the listener to the class Trace/
TraceManager.addNotificationListener(listener, filter, null);