（原创）创建非纵深结构的动态内表

       有时我们最终要输出的内表字段并不是固定的，可能随着情况的变化而变化，此时我们就需要用到动态内表。一般来讲，创建动态内表的方式有两种。一种是调用cl_alv_table_create 的create_dynamic_table 方法，这种创建只能适用于最终创建的动态内表是非纵深结构(参考的扁平结构内未嵌套扁平结构)的情况，还有一种是调用类CL_ABAP_STRUCTDESCR和类CL_ABAP_TABLEDESCR的相关方法，可以创建纵深结构的动态内表。

纵深结构示例（扁平结构LVC_S_SCOL内嵌套扁平结构LVC_S_COLO）：

       这次先给出一个创建非纵深结构动态内表的DEMO示例：

输出目标：根据选择屏幕中填入的列名输出ALV，列名之间用逗号分隔。

源代码：

*&---------------------------------------------------------------------*
*& Report Z15540_DYN01
*&---------------------------------------------------------------------*
*&
*&---------------------------------------------------------------------*
REPORT z15540_dyn01.
DATA:gs_layo TYPE lvc_s_layo,
     gs_fcat TYPE lvc_s_fcat,
     gt_fcat TYPE lvc_t_fcat.
DATA:dyn_table TYPE REF TO data,
     dyn_line  TYPE REF TO data.
DATA gt_col TYPE TABLE OF string.
FIELD-SYMBOLS:<fs_table> TYPE STANDARD TABLE.

PARAMETERS p_col TYPE string OBLIGATORY."填入动态创建的列名，以逗号分隔

START-OF-SELECTION.
  PERFORM frm_layo.
  PERFORM frm_fcat.
  PERFORM frm_create_dyn."创建动态内表&&填充数据
  PERFORM frm_alv_dispaly.

*&---------------------------------------------------------------------*
*& Form FRM_LAYO
*&---------------------------------------------------------------------*
*& text
*&---------------------------------------------------------------------*
*& -->  p1        text
*& <--  p2        text
*&---------------------------------------------------------------------*
FORM frm_layo .
  CLEAR gs_layo.
  gs_layo-zebra = 'X'.
  gs_layo-cwidth_opt = 'X'.
ENDFORM.
*&---------------------------------------------------------------------*
*& Form FRM_FCAT
*&---------------------------------------------------------------------*
*& text
*&---------------------------------------------------------------------*
*& -->  p1        text
*& <--  p2        text
*&---------------------------------------------------------------------*
FORM frm_fcat .

  SPLIT p_col AT ',' INTO TABLE gt_col.
  LOOP AT gt_col ASSIGNING FIELD-SYMBOL(<fs_col>).
    gs_fcat-fieldname = <fs_col>.
    gs_fcat-coltext = <fs_col> && '描述' .
    gs_fcat-ref_table = 'MAKT'.
    gs_fcat-ref_field = 'MAKTX'.
    APPEND gs_fcat TO gt_fcat.
    CLEAR gs_fcat.
  ENDLOOP.
ENDFORM.
*&---------------------------------------------------------------------*
*& Form FRM_CREATE_DYN
*&---------------------------------------------------------------------*
*& text
*&---------------------------------------------------------------------*
*& -->  p1        text
*& <--  p2        text
*&---------------------------------------------------------------------*
FORM frm_create_dyn .
  DATA: lv_col TYPE i,
        lv_index(2).
  "创建动态内表
  CALL METHOD cl_alv_table_create=>create_dynamic_table
    EXPORTING
*     i_style_table   =
      it_fieldcatalog = gt_fcat
*     i_length_in_byte          =
    IMPORTING
      ep_table        = dyn_table
*     e_style_fname   =
*  EXCEPTIONS
*     generate_subpool_dir_full = 1
*     others          = 2
    .
  ASSIGN dyn_table->* TO <fs_table>.
  CREATE DATA dyn_line LIKE LINE OF <fs_table>.
  ASSIGN dyn_line->* TO FIELD-SYMBOL(<fs_line>).
  "填充数据
  DESCRIBE TABLE gt_col LINES lv_col.
  DO lv_col TIMES.
    lv_index = sy-index.
    ASSIGN COMPONENT sy-index OF STRUCTURE <fs_line> TO FIELD-SYMBOL(<fs_field>).
    <fs_field> = '填充值' && lv_index .
  ENDDO.
  APPEND <fs_line> TO <fs_table>.
  DO lv_col TIMES.
    lv_index = sy-index.
    ASSIGN COMPONENT sy-index OF STRUCTURE <fs_line> TO <fs_field>.
    <fs_field> = '填充值' && lv_index .
  ENDDO.
  APPEND <fs_line> TO <fs_table>.
  DO lv_col TIMES.
    lv_index = sy-index.
    ASSIGN COMPONENT sy-index OF STRUCTURE <fs_line> TO <fs_field>.
    <fs_field> = '填充值' && lv_index .
  ENDDO.
  APPEND <fs_line> TO <fs_table>.

ENDFORM.
*&---------------------------------------------------------------------*
*& Form FRM_ALV_DISPALY
*&---------------------------------------------------------------------*
*& text
*&---------------------------------------------------------------------*
*& -->  p1        text
*& <--  p2        text
*&---------------------------------------------------------------------*
FORM frm_alv_dispaly .
  "显示ALV
  CALL FUNCTION 'REUSE_ALV_GRID_DISPLAY_LVC'
    EXPORTING
*     I_CALLBACK_PROGRAM = SY-REPID
      is_layout_lvc   = gs_layo
      it_fieldcat_lvc = gt_fcat
    TABLES
      t_outtab        = <fs_table>
    EXCEPTIONS
      program_error   = 1
      OTHERS          = 2.
*if SY-SUBRC <> 0.
*  message id SY-MSGID type SY-MSGTY number SY-MSGNO
*    with SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
*endif.

ENDFORM.