code: private void store() throws IOException
     {
        Properties props = new Properties();
  
        // store mappings in properties
        Iterator<String> iter = prefixToURI.keySet().iterator();
        while (iter.hasNext())
        {
           String prefix = iter.next();
           String uri = prefixToURI.get(prefix);
           props.setProperty(prefix, uri);
        }
  
        OutputStream out = PrivilegedFileHelper.fileOutputStream(storage);
        try
        {
           out = new BufferedOutputStream(out);
           props.store(out, null);
        }
        finally
        {
           // make sure stream is closed
           out.close();
        }
     }
docs: Writes the currently known mappings into a .properties file.
  
  @throws IOException if an error occurs while writing the file.