abap object-oriented－－基本定义语句

这一节我们来看一下abap oo的定义语句，包括类，方法，事件，属性，接口。

1． 定义类

******************************************
* Definition part
******************************************
CLASS xxx DEFINITION.
*------------------------------
* Public section
*------------------------------
  PUBLIC SECTION.
    TYPES:
    DATA: 
*   Static data
    CLASS-DATA:
*   Methods
    METHODS:
*     Using the constructor to initialize parameters
       constructor    IMPORTING xxx type yyy,              
*     Method with parameters
      mm1 IMPORTING iii   TYPE ttt.
*     Method without parameters
      mm2.
*   Static methods
    CLASS-METHODS:      
*---------------------------------------------------*
* Protected section. Also accessible by subclasses
*---------------------------------------------------
  PROTECTED SECTION.
*---------------------------------------------------
* Private section. Not accessible by subclasses
*---------------------------------------------------
  PRIVATE SECTION.
ENDCLASS.
******************************************
* Implementation part
******************************************
CLASS lcl_airplane IMPLEMENTATION.
  METHOD constructor.
  ENDMETHOD.
  METHOD mm1.
  ENDMETHOD.
  METHOD mm2.
  ENDMETHOD.
ENDCLASS.

2． 定义继承

CLASS xxx DEFINITION INHERITING FROM yyy.

3． 定义接口

INTERFACE lif_document
  DATA:          author type ref to lcl_author.
  METHODS:  print,
            display.
ENDINTERFACE.
CLASS lcl_text_document DEFINITION.
   PUBLIC SECTION.
      INTERFACES lif_document.
      METHODS     display.
ENDCLASS.
CLASS lcl_text_document IMPLEMENTTION.
  METHOD lif_document~print.
  ENDMETHOD.
  METHOD lif_document~display
  ENDMETHOD.
  METHOD display.
  ENDMETHOD.
ENDCLASS.
REPORT zzz.
  DATA: text_doc TYPE REF TO lcl_document.
  Start-of-selection.
    CREATE OBJECT text_doc.
    CALL METHOD text_doc->lif_document~print.
    CALL METHOD text_doc->lif_document~display.
CALL METHOD text_doc->display.

4． 事件

CLASS <classname> DEFINITION.
  EVENTS: <event> EXPORTING VALUE (<ex_par>) TYPE type.
CLASS <classname> IMPLEMENTATION.
  METHOD <m>:
    RAISE EVENT <event> EXPORTING <ex_par> = <act_par>.
Handling events:
CLASS <classname> DEFINITION.
  METHODS: <on_event> FOR <event> OF {<classname> ! <interface> }
IMPORTING <imp_par1>...<imp_parN> SENDER.
Setting handler  
SET HANDLER <ref_handle> <on_event> FOR {<ref_sender> ! FOR ALL INSTANCES}
           [ACTIVATION <var>]