Steps to Reproduce

1. <spreadsheet src="~./blank.xlsx"/>
2. run the zul

Current Result

org.zkoss.zk.ui.UiException: resource for ~./blank.xlsx not found.
at io.keikai.ui.Spreadsheet.getSBook(Spreadsheet.java:735)
at io.keikai.ui.Spreadsheet.getSelectedSSheet(Spreadsheet.java:918)
at io.keikai.ui.Spreadsheet.doInvalidate(Spreadsheet.java:2890)
at io.keikai.ui.Spreadsheet.invalidate(Spreadsheet.java:2712)
at io.keikai.ui.Spreadsheet.setSrc(Spreadsheet.java:990)

Expected Result

keikai can load the file without the error

Debug Information

• almost all zk components can accept classpath web resource path ~./ (https://www.zkoss.org/wiki/ZK_Developer%27s_Reference/UI_Composing/ZUML/Include_a_Page#Classpath_Web_Resource_Path)
• it allows a spreadsheet in a spring-boot app (jar package) to load file in the classpath
• Spreadsheet.getSBook()

  					if (_src.startsWith("/")) {// try to load by application
  						// context.
  						WebApp wapp = Executions.getCurrent().getDesktop().getWebApp();
  						String path = wapp.getRealPath(_src);
  						if (path != null) {
  							File file = new File(path);
  //							if (file.isDirectory())
  //								throw new IllegalArgumentException("Your input source is a directory, not a vaild file");
  							if (file.exists())
  								url = file.toURI().toURL();
  						} else
  							url = wapp.getResource(_src); 
  					}
  

  wapp.getResource(_src) can load the ~./ correctly but wrong implementation