ABAP Operaciones de archivo: OPEN DATASET, READ, TRANSFER

OPEN DATASET <nombrearchivo>
  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 <mensaje> ].

READ DATASET <nombrearchivo> INTO <datos> [ LENGTH <longitud> ].
TRANSFER <datos> TO <nombrearchivo> [ LENGTH <longitud> ].

CLOSE DATASET <nombrearchivo>.
DELETE DATASET <nombrearchivo>.

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

" Abrir archivo para escritura
OPEN DATASET lv_file FOR OUTPUT IN TEXT MODE
  ENCODING UTF-8
  MESSAGE lv_message.

IF sy-subrc = 0.
  " Escribir lineas
  TRANSFER 'Linea 1: Hola Mundo' TO lv_file.
  TRANSFER 'Linea 2: ABAP es genial' TO lv_file.
  TRANSFER 'Linea 3: Fin del archivo' TO lv_file.

  CLOSE DATASET lv_file.
  WRITE: / 'Archivo escrito exitosamente'.
ELSE.
  WRITE: / 'Error:', 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.
  " Leer linea por linea
  DO.
    READ DATASET lv_file INTO lv_line.
    IF sy-subrc <> 0.
      EXIT.  " Fin del archivo
    ENDIF.

    WRITE: / lv_line.
  ENDDO.

  CLOSE DATASET lv_file.
ELSE.
  WRITE: / 'No se pudo abrir el archivo'.
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.

  " Procesamiento
  WRITE: / 'Lineas leidas:', lines( lt_lines ).
ENDIF.

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

lt_lines = VALUE #(
  ( `Nombre;Edad;Ciudad` )
  ( `Juan;30;Madrid` )
  ( `Ana;25;Barcelona` )
  ( `Pedro;35;Valencia` )
).

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: / 'Exportadas:', lines( lt_lines ), 'lineas'.
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.
  " Saltar linea de cabecera
  READ DATASET lv_file INTO lv_line.

  " Leer lineas de datos
  DO.
    READ DATASET lv_file INTO lv_line.
    IF sy-subrc <> 0.
      EXIT.
    ENDIF.

    " Dividir linea
    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.

" Mostrar resultados
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.

" Datos de prueba
lt_orders = VALUE #(
  ( id = 1 customer = 'Garcia' amount = '100.50' )
  ( id = 2 customer = 'Lopez' amount = '250.00' )
  ( id = 3 customer = 'Martinez' amount = '75.25' )
).

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

IF sy-subrc = 0.
  " Escribir cabecera
  TRANSFER 'ID;Cliente;Monto' TO lv_file.

  " Lineas de datos
  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.

    " Concatenar datos
    CONCATENATE lv_data lv_buffer(lv_length) INTO lv_data IN BYTE MODE.
  ENDDO.

  CLOSE DATASET lv_file.
  WRITE: / 'Leidos:', xstrlen( lv_data ), 'bytes'.
ENDIF.

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

" Datos binarios (por ej. de BD o procesamiento)
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.

" Agregar fecha/hora al log
lv_line = |{ sy-datum DATE = ISO } { sy-uzeit TIME = ISO }: Nueva entrada|.

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'.

" Verificar si el archivo existe (abriendo)
OPEN DATASET lv_file FOR INPUT IN TEXT MODE ENCODING DEFAULT.

IF sy-subrc = 0.
  CLOSE DATASET lv_file.
  WRITE: / 'Archivo existe'.

  " Eliminar archivo
  DELETE DATASET lv_file.

  IF sy-subrc = 0.
    WRITE: / 'Archivo eliminado'.
  ENDIF.
ELSE.
  WRITE: / 'Archivo no existe'.
ENDIF.

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

" Abrir directorio
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: / 'Error al abrir:'.
  WRITE: / lv_message.
  WRITE: / 'Codigo de retorno:', sy-subrc.
ENDIF.

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

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

" Automatico (dependiente del servidor)
OPEN DATASET lv_file FOR OUTPUT IN TEXT MODE
  ENCODING UTF-8
  WITH NATIVE LINEFEED.

" Smart: Escribe como Native, Lectura detecta automaticamente
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.
  " Obtener posicion
  GET DATASET lv_file POSITION lv_pos.
  WRITE: / 'Posicion actual:', lv_pos.

  " Saltar a posicion
  SET DATASET lv_file POSITION 100.

  " Leer desde posicion 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.

    " Procesamiento sin guardar todas las lineas
    " process_line( lv_buffer ).

    " Mostrar progreso (cada 10000 lineas)
    IF lv_count MOD 10000 = 0.
      WRITE: / 'Procesadas:', lv_count, 'lineas'.
    ENDIF.
  ENDDO.

  CLOSE DATASET lv_file.
  WRITE: / 'Total:', lv_count, 'lineas'.
ENDIF.

DATA: lv_temp_file TYPE string,
      lv_guid      TYPE sysuuid_c32.

" Generar nombre de archivo unico
lv_guid = cl_system_uuid=>create_uuid_c32_static( ).
lv_temp_file = |/tmp/temp_{ lv_guid }.txt|.

" Usar archivo temporal
OPEN DATASET lv_temp_file FOR OUTPUT IN TEXT MODE ENCODING UTF-8.
TRANSFER 'Datos temporales' TO lv_temp_file.
CLOSE DATASET lv_temp_file.

" ... Procesamiento ...

" Limpiar
DELETE DATASET lv_temp_file.

" En ABAP Cloud: Interfaz FILE no disponible
" En su lugar: CL_ABAP_FILE_UTILITIES o XCO

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

" Verificar si existe
IF lo_file->exists( ).
  " Leer
  DATA(lv_content) = lo_file->read( )->as_string( ).
ENDIF.