swt文件选择框

FileDialog fileselect=new FileDialog(shell,SWT.SINGLE);
                         fileselect.setFilterNames(new
String[]{"*.xls","所有文件"});
                        
fileselect.setFilterExtensions(new String[]{"*.xls","*.*"});

                        String url="";

                        url=fileselect.open();
                        System.out.println(url);