这个压缩包里的都是超级经典的java例子

				
				
				
				Getting the Roots of the Preference Trees (Java Developers Almanac Example)
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				The Java Developers Almanac 1.4
				
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				  e411. Getting the Roots of the Preference Trees
				
				There are two preference trees --- the system tree and the user tree.
				The root of these trees is retrieved using
				Preferences.systemRoot() and Preferences.userRoot().  The
				roots are required when creating and retrieving preference nodes.  See
				e413 Retrieving a Preference Node for an example of retrieving
				preference nodes using a root.
				
				
				    // Get the system root
				    Preferences prefs = Preferences.systemRoot();
				    
				    // Get the user root
				    prefs = Preferences.userRoot();
				    
				    // The name of a root is ""
				    String name = prefs.name();
				    
				    // The parent of a root is null
				    Preferences parent = prefs.parent();
				    
				    // The absolute path of a root is "/"
				    String path = prefs.absolutePath();
				
				
				
				
				             Related Examples
				
				
				
				
				e412. 
				    Creating a Preference Node
				
				
				
				e413. 
				    Retrieving a Preference Node
				
				
				
				e414. 
				    Removing a Preference Node
				
				
				
				e415. 
				    Determining If a Preference Node Exists
				
				
				
				e416. 
				    Retrieving the Parent and Child Nodes of a Preference Node
				
				
				
				e417. 
				    Finding a Preference in a Preference Tree
				
				
				
				
				
				
				
				
				        See also: 
				
				    Events
				  
				
				
				    Importing and Exporting
				  
				
				
				
				
				
				
				
				
				
				© 2002 Addison-Wesley.