No front-end printing is possible in Web-Dynpro.
OSS note from BC-CCM-PRN-PC: 616762
When you try to print on a printer defined with access method 'F' or 'G', there is no print output and the relevant spool request remains in the 'Is waiting' status.
如果在BSP或者Web-Dynpro中要Print或者Print Preview, 需要二次开发, 先生成PDF, 再使用Brower中的PDF plug-in.