CL_GUI_FRONTEND_SERVICES（SAP操作Windows文件）
这个类下面的方法均为静态方法，引用的时候以=>来引用方法
注意：在执行CL_GUI_FRONTEND_SERVICES的一些方法后，比如GET****，注册表操作等，要加一个
CALL METHOD CL_GUI_CFW=>FLUSH .
CALL METHOD CL_GUI_CFW=>FLUSH .
CALL METHOD cl_gui_frontend_services=>get_temp_directory CHANGING temp_dir = dir. WRITE : /'1:', dir. CALL METHOD cl_gui_cfw=>flush. WRITE : /'2:', dir.
结果：
常用GET***方法：
| GET_CACHE_PROP | Read Value of a Cache Property |
| GET_COMPUTER_NAME | Get Computer Name |
| GET_DESKTOP_DIRECTORY | Get Desktop Directory |
| GET_DRIVE_FREE_SPACE_MEGABYTE | Returns Drive's Free Space in MB |
| GET_DRIVE_TYPE | Get Drive Type |
| GET_FILE_SEPARATOR | Get File Separator |
| GET_FREE_SPACE_FOR_DRIVE | Returns Free Space on Drive |
| GET_GUI_PROPERTIES | Returns Stream of GUI Properties |
| GET_GUI_VERSION | Returns the Upload/Download Paths |
| GET_IP_ADDRESS | Gets IP Address |
| GET_LF_FOR_DESTINATION_GUI | Destinations' SAP GUI Line Feed |
| GET_PLATFORM | Return Operating System Platform |
| GET_PROPERTY | Get_Property |
| GET_PROPERTY_GUI_OBJECT | GetProperty rc=GUI_OBJECT, You Can Check obj With 'IS_VALID' |
| GET_SAPGUI_DIRECTORY | Gets GUI Start Directory |
| GET_SAPGUI_WORKDIR | Returns ..\Documents and SettingsDNRSAPWorkdir (Example) |
| GET_SAPLOGON_ENCODING | Return to saplogon Codepage |
| GET_SYSTEM_DIRECTORY | Get System Directory |
| GET_TEMP_DIRECTORY | Returns the Path to the TEMP Directory |
| GET_UPLOAD_DOWNLOAD_PATH | returns the upload/download paths |
| GET_USER_NAME | Get User Name |
| GET_WINDOWS_DIRECTORY | Get Windows Directory |