ABAP Dateioperationen: OPEN DATASET, READ, TRANSFER

OPEN DATASET <dateiname>
  FOR { INPUT | OUTPUT | APPENDING | UPDATE }
  IN { TEXT MODE | BINARY MODE | LEGACY TEXT MODE }
  [ ENCODING { DEFAULT | UTF-8 | NON-UNICODE } ]
  [ WITH { SMART | NATIVE | UNIX | WINDOWS } LINEFEED ]
  [ MESSAGE <nachricht> ].

READ DATASET <dateiname> INTO <daten> [ LENGTH <länge> ].
TRANSFER <daten> TO <dateiname> [ LENGTH <länge> ].

CLOSE DATASET <dateiname>.
DELETE DATASET <dateiname>.

DATA: lv_file    TYPE string VALUE '/tmp/output.txt',
      lv_message TYPE string.

" Datei zum Schreiben öffnen
OPEN DATASET lv_file FOR OUTPUT IN TEXT MODE
  ENCODING UTF-8
  MESSAGE lv_message.

IF sy-subrc = 0.
  " Zeilen schreiben
  TRANSFER 'Zeile 1: Hallo Welt' TO lv_file.
  TRANSFER 'Zeile 2: ABAP ist toll' TO lv_file.
  TRANSFER 'Zeile 3: Ende der Datei' TO lv_file.

  CLOSE DATASET lv_file.
  WRITE: / 'Datei erfolgreich geschrieben'.
ELSE.
  WRITE: / 'Fehler:', lv_message.
ENDIF.

DATA: lv_file TYPE string VALUE '/tmp/input.txt',
      lv_line TYPE string.

OPEN DATASET lv_file FOR INPUT IN TEXT MODE
  ENCODING UTF-8.

IF sy-subrc = 0.
  " Zeilenweise lesen
  DO.
    READ DATASET lv_file INTO lv_line.
    IF sy-subrc <> 0.
      EXIT.  " Ende der Datei
    ENDIF.

    WRITE: / lv_line.
  ENDDO.

  CLOSE DATASET lv_file.
ELSE.
  WRITE: / 'Datei konnte nicht geöffnet werden'.
ENDIF.

DATA: lv_file  TYPE string VALUE '/tmp/data.txt',
      lv_line  TYPE string,
      lt_lines TYPE TABLE OF string.

OPEN DATASET lv_file FOR INPUT IN TEXT MODE ENCODING UTF-8.

IF sy-subrc = 0.
  DO.
    READ DATASET lv_file INTO lv_line.
    IF sy-subrc <> 0.
      EXIT.
    ENDIF.
    APPEND lv_line TO lt_lines.
  ENDDO.

  CLOSE DATASET lv_file.

  " Verarbeitung
  WRITE: / 'Gelesene Zeilen:', lines( lt_lines ).
ENDIF.

DATA: lv_file  TYPE string VALUE '/tmp/export.txt',
      lt_lines TYPE TABLE OF string.

lt_lines = VALUE #(
  ( `Name;Alter;Stadt` )
  ( `Max;30;Berlin` )
  ( `Anna;25;München` )
  ( `Peter;35;Hamburg` )
).

OPEN DATASET lv_file FOR OUTPUT IN TEXT MODE ENCODING UTF-8.

IF sy-subrc = 0.
  LOOP AT lt_lines INTO DATA(lv_line).
    TRANSFER lv_line TO lv_file.
  ENDLOOP.

  CLOSE DATASET lv_file.
  WRITE: / 'Exportiert:', lines( lt_lines ), 'Zeilen'.
ENDIF.

TYPES: BEGIN OF ty_customer,
         name TYPE string,
         age  TYPE i,
         city TYPE string,
       END OF ty_customer.

DATA: lv_file      TYPE string VALUE '/tmp/customers.csv',
      lv_line      TYPE string,
      lt_customers TYPE TABLE OF ty_customer,
      lt_fields    TYPE TABLE OF string.

OPEN DATASET lv_file FOR INPUT IN TEXT MODE ENCODING UTF-8.

IF sy-subrc = 0.
  " Kopfzeile überspringen
  READ DATASET lv_file INTO lv_line.

  " Datenzeilen lesen
  DO.
    READ DATASET lv_file INTO lv_line.
    IF sy-subrc <> 0.
      EXIT.
    ENDIF.

    " Zeile splitten
    SPLIT lv_line AT ';' INTO TABLE lt_fields.

    IF lines( lt_fields ) >= 3.
      APPEND VALUE ty_customer(
        name = lt_fields[ 1 ]
        age  = CONV #( lt_fields[ 2 ] )
        city = lt_fields[ 3 ]
      ) TO lt_customers.
    ENDIF.
  ENDDO.

  CLOSE DATASET lv_file.
ENDIF.

" Ergebnis anzeigen
LOOP AT lt_customers INTO DATA(ls_cust).
  WRITE: / ls_cust-name, ls_cust-age, ls_cust-city.
ENDLOOP.

DATA: lv_file TYPE string VALUE '/tmp/export.csv',
      lv_line TYPE string.

DATA: lt_orders TYPE TABLE OF ty_order.

" Testdaten
lt_orders = VALUE #(
  ( id = 1 customer = 'Müller' amount = '100.50' )
  ( id = 2 customer = 'Schmidt' amount = '250.00' )
  ( id = 3 customer = 'Weber' amount = '75.25' )
).

OPEN DATASET lv_file FOR OUTPUT IN TEXT MODE ENCODING UTF-8.

IF sy-subrc = 0.
  " Header schreiben
  TRANSFER 'ID;Kunde;Betrag' TO lv_file.

  " Datenzeilen
  LOOP AT lt_orders INTO DATA(ls_order).
    lv_line = |{ ls_order-id };{ ls_order-customer };{ ls_order-amount }|.
    TRANSFER lv_line TO lv_file.
  ENDLOOP.

  CLOSE DATASET lv_file.
ENDIF.

DATA: lv_file   TYPE string VALUE '/tmp/image.png',
      lv_data   TYPE xstring,
      lv_buffer TYPE x LENGTH 1024,
      lv_length TYPE i.

OPEN DATASET lv_file FOR INPUT IN BINARY MODE.

IF sy-subrc = 0.
  DO.
    READ DATASET lv_file INTO lv_buffer LENGTH lv_length.
    IF sy-subrc <> 0.
      EXIT.
    ENDIF.

    " Daten anhängen
    CONCATENATE lv_data lv_buffer(lv_length) INTO lv_data IN BYTE MODE.
  ENDDO.

  CLOSE DATASET lv_file.
  WRITE: / 'Gelesen:', xstrlen( lv_data ), 'Bytes'.
ENDIF.

DATA: lv_file TYPE string VALUE '/tmp/output.bin',
      lv_data TYPE xstring.

" Binärdaten (z.B. aus DB oder Verarbeitung)
lv_data = 'A1B2C3D4E5F6'.

OPEN DATASET lv_file FOR OUTPUT IN BINARY MODE.

IF sy-subrc = 0.
  TRANSFER lv_data TO lv_file.
  CLOSE DATASET lv_file.
ENDIF.

DATA: lv_file TYPE string VALUE '/tmp/log.txt',
      lv_line TYPE string.

" Datum/Zeit zum Log hinzufügen
lv_line = |{ sy-datum DATE = ISO } { sy-uzeit TIME = ISO }: Neuer Eintrag|.

OPEN DATASET lv_file FOR APPENDING IN TEXT MODE ENCODING UTF-8.

IF sy-subrc = 0.
  TRANSFER lv_line TO lv_file.
  CLOSE DATASET lv_file.
ENDIF.

DATA: lv_file TYPE string VALUE '/tmp/temp.txt'.

" Prüfen ob Datei existiert (durch Öffnen)
OPEN DATASET lv_file FOR INPUT IN TEXT MODE ENCODING DEFAULT.

IF sy-subrc = 0.
  CLOSE DATASET lv_file.
  WRITE: / 'Datei existiert'.

  " Datei löschen
  DELETE DATASET lv_file.

  IF sy-subrc = 0.
    WRITE: / 'Datei gelöscht'.
  ENDIF.
ELSE.
  WRITE: / 'Datei existiert nicht'.
ENDIF.

DATA: lv_dir      TYPE string VALUE '/tmp/',
      lt_files    TYPE TABLE OF string,
      lv_filename TYPE string.

" Verzeichnis öffnen
CALL FUNCTION 'EPS_GET_DIRECTORY_LISTING'
  EXPORTING
    dir_name               = CONV eps2path( lv_dir )
  TABLES
    dir_list               = lt_files
  EXCEPTIONS
    invalid_eps_subdir     = 1
    sapgparam_failed       = 2
    build_directory_failed = 3
    no_authorization       = 4
    read_directory_failed  = 5
    too_many_read_errors   = 6
    empty_directory_list   = 7
    OTHERS                 = 8.

IF sy-subrc = 0.
  LOOP AT lt_files INTO lv_filename.
    WRITE: / lv_filename.
  ENDLOOP.
ENDIF.

DATA: lv_file    TYPE string VALUE '/nonexistent/path/file.txt',
      lv_message TYPE string.

OPEN DATASET lv_file FOR INPUT IN TEXT MODE
  ENCODING UTF-8
  MESSAGE lv_message.

IF sy-subrc <> 0.
  WRITE: / 'Fehler beim Öffnen:'.
  WRITE: / lv_message.
  WRITE: / 'Return Code:', sy-subrc.
ENDIF.

" Unix-Zeilenumbruch (LF)
OPEN DATASET lv_file FOR OUTPUT IN TEXT MODE
  ENCODING UTF-8
  WITH UNIX LINEFEED.

" Windows-Zeilenumbruch (CRLF)
OPEN DATASET lv_file FOR OUTPUT IN TEXT MODE
  ENCODING UTF-8
  WITH WINDOWS LINEFEED.

" Automatisch (abhängig vom Server)
OPEN DATASET lv_file FOR OUTPUT IN TEXT MODE
  ENCODING UTF-8
  WITH NATIVE LINEFEED.

" Smart: Schreiben wie Native, Lesen erkennt automatisch
OPEN DATASET lv_file FOR INPUT IN TEXT MODE
  ENCODING UTF-8
  WITH SMART LINEFEED.

DATA: lv_file TYPE string VALUE '/tmp/data.bin',
      lv_data TYPE x LENGTH 100,
      lv_pos  TYPE i.

OPEN DATASET lv_file FOR UPDATE IN BINARY MODE.

IF sy-subrc = 0.
  " Position ermitteln
  GET DATASET lv_file POSITION lv_pos.
  WRITE: / 'Aktuelle Position:', lv_pos.

  " An Position springen
  SET DATASET lv_file POSITION 100.

  " Lesen ab Position 100
  READ DATASET lv_file INTO lv_data.

  CLOSE DATASET lv_file.
ENDIF.

CONSTANTS: c_buffer_size TYPE i VALUE 8192.

DATA: lv_file   TYPE string VALUE '/tmp/large_file.txt',
      lv_buffer TYPE string,
      lv_count  TYPE i.

OPEN DATASET lv_file FOR INPUT IN TEXT MODE ENCODING UTF-8.

IF sy-subrc = 0.
  DO.
    READ DATASET lv_file INTO lv_buffer.
    IF sy-subrc <> 0.
      EXIT.
    ENDIF.

    lv_count = lv_count + 1.

    " Verarbeitung ohne Speichern aller Zeilen
    " process_line( lv_buffer ).

    " Fortschritt anzeigen (alle 10000 Zeilen)
    IF lv_count MOD 10000 = 0.
      WRITE: / 'Verarbeitet:', lv_count, 'Zeilen'.
    ENDIF.
  ENDDO.

  CLOSE DATASET lv_file.
  WRITE: / 'Gesamt:', lv_count, 'Zeilen'.
ENDIF.

DATA: lv_temp_file TYPE string,
      lv_guid      TYPE sysuuid_c32.

" Eindeutigen Dateinamen generieren
lv_guid = cl_system_uuid=>create_uuid_c32_static( ).
lv_temp_file = |/tmp/temp_{ lv_guid }.txt|.

" Temporäre Datei verwenden
OPEN DATASET lv_temp_file FOR OUTPUT IN TEXT MODE ENCODING UTF-8.
TRANSFER 'Temporäre Daten' TO lv_temp_file.
CLOSE DATASET lv_temp_file.

" ... Verarbeitung ...

" Aufräumen
DELETE DATASET lv_temp_file.

" In ABAP Cloud: FILE-Interface nicht verfügbar
" Stattdessen: CL_ABAP_FILE_UTILITIES oder XCO

" Beispiel mit XCO (Cloud)
DATA(lo_file) = xco_cp=>file( '/tmp/test.txt' ).

" Prüfen ob existiert
IF lo_file->exists( ).
  " Lesen
  DATA(lv_content) = lo_file->read( )->as_string( ).
ENDIF.