Java Notes-12(Preferences API, The Logging API)

Summary:Preferences API, The Logging API

- The Preferences API is like a portable version of the Windows registry, a mini-database in which you can keep small amounts of information, accessible to all applications

-Preferences are stored logically in a tree. 

Preferences prefs = Preferences.userRoot().node("oreilly/learningjava");
prefs.put("author", "Niemeyer");
prefs.putInt("edition", 4);
String author = prefs.get("author", "unknown");
int edition = prefs.getInt("edition", -1);

-The  node() method accepts either a relative or an absolute path. 

Preferences prefs =
Preferences.userRoot().node("oreilly").node("learningjava");

Preferences prefs =
Preferences.userRoot().node("/oreilly/learningjava");
prefs.addPreferenceChangeListener( new PreferenceChangeListener() {
public void preferenceChange(PreferenceChangeEvent e) {
System.out.println("Value: " + e.getKey()
+ " changed to "+ e.getNewValue() );
}
} );

 -The heart of the logging framework is the logger, an instance of  java.util.logging.Logger . 

package com.oreilly.learnjava;
public class Book {
static Logger log = Logger.getLogger("com.oreilly.learnjava.Book");

log.warning("Disk 90% full.");
log.info("New user joined chat room.");

Logger.global.info("Doing foo...")

Java Notes-12(Preferences API, The Logging API)

原文：http://blog.csdn.net/yu444/article/details/45601837