动态更新properties

 public static void reloadProperties() {
	        //Get a list of files loaded
	     ArrayList<String> files = getFileList();

	     //Cycle through list and reload all files
	        for (int icnt =0;icnt < files.size();icnt++) {
	            loadPropertiesFile(files.get(icnt),true);
	        }
	    }
	 
	  public static boolean loadPropertiesFile(String filename, boolean reload) {
	      //If property file is already loaded and reload is required then remove it from the loaded file list.
	      if (propfiles.containsKey(filename)) {
	             if (!reload) return true;
	             propfiles.remove(filename);
	         }

	             try {
	              //Find the property file on the class path and load it.
	              System.out.println("Loading properties file: "+filename);
	                 ClassLoader loader = Thread.currentThread().getContextClassLoader();
	                 InputStream is = loader.getResourceAsStream(filename);
	                 Properties props = new Properties();
	                 props.load(is);
	                 //Add it to the hashtable
	                 propfiles.put(filename,props);
	                 return true;
	             }
	             catch (Exception e) {
	              System.out.println("Failed to load properties file: "+e.getMessage());
	                 return false;
	             }
	     }
	  
	     /**
	      * getFileList  - returns a sorted list of property file names that have been loaded
	      */
	     public static ArrayList<String> getFileList() {
	         //Get empty list
	      ArrayList<String> files = new ArrayList<String>();

	      //Cycle through property files hash table and add names to the return list
	         Set<String> keys = propfiles.keySet();
	         Iterator it = keys.iterator();
	         while (it.hasNext()) {
	             files.add((String) it.next());
	         }

	         //Sort list
	         Collections.sort(files);
	         return files;
	     }
	     
	     public static String getValue(String propertiesFile,String key) {
	         // If property file is not load it then load it now
	      if (!propfiles.containsKey(propertiesFile)) {
	             if (!loadPropertiesFile(propertiesFile,true)) {
	                 throw new RuntimeException("Failed to load properties file: "+propertiesFile);
	             }
	         }
	      //Get the property file from the hashmap
	         Properties props = propfiles.get(propertiesFile);
	         //Return the property value
	         try {
	          System.out.println("Getting properties: "+key);
	             return props.getProperty(key);
	         }
	         catch (Exception e) {
	          System.out.println("Failed to find property in file");
	             throw new RuntimeException("Failed to find property");
	         }
	     }

       public static void main(String[] args) {

		 String value=getValue("my.properties","key1");
		  System.out.println("Printing Value:" + value);
		  reloadProperties();
		  value=getValue("my.properties","key1");
		  System.out.println("Printing Value:" + value);
		
	}