ABAP 面向对象
ABAP 面向对象
目录
- ABAP 面向对象
- 类-CLASS
-
- EXPORTING和IMPORTING
-
- 执行结果
- 接收decelerate方法返回的变量r1
-
- 方法1
- 执行结果
- 继承
-
- 基类的定义和实现
- 子类的定义和实现
-
- 主程序调用
- 构造函数constructor
-
-
- 执行效果
-
- 重写和super关键字
-
- OPTIONAL 和 DEFAULT
-
- OPTIONAL
- DEFAULT
- car类的定义和实现
- 运行结果
-
- 不传值时
- 传值时
- 完整程序
- 接口-INTERFACE
-
- 接口定义
-
- 报错
- 实现接口方法
- 调用接口方法
- 运行效果
- 通过接口访问成员
-
- 完整程序
- 接口引用间赋值
-
- 报错
- object类型不能赋值成接口类型
-
- ?= 类、接口等类型的向下类型转换
- 事件
-
- 声明事件
- 触发事件
- 接收事件
- 注册事件
- 示例
-
- 运行效果
类-CLASS
EXPORTING和IMPORTING
创建程序
程序名：ZTEST_CLASS02_LHY
事务代码：SE38
输入程序名：ZTEST_CLASS02_LHY，点击“创建”按钮：
输入标题，选择标题，点击“创建”：
点击“本地对象”按钮：
编写程序履历
*&---------------------------------------------------------------------*
*& Report ZTEST_CLASS_02_LHY
*&---------------------------------------------------------------------*
*& 类型：Report
*& 创建人：LiuHongyu
*& 创建时间：2024.1.22
*& 描述：面对对象学习测试
************************************************************************
* Changed History
*------------- ------------- --------------- ---------------
* 版本 修改人 修改时间 修改描述
*------------- ------------- --------------- ---------------
* N LiuHongyu 2024.1.22 创建
*------------- ------------- --------------- ---------------
************************************************************************
*&---------------------------------------------------------------------*
编写代码
类的定义和实现
1）定义一个car类
2）show_speed方法是用于展示speed
3）accelerrate方法有传入参数i，传出参数out_speed。
*---------------------------------------------------------------------*
* 类定义
*---------------------------------------------------------------------*
CLASS car DEFINITION.
PUBLIC SECTION.
DATA: speed TYPE i,
weight TYPE i.
METHODS:show_speed,
accelerate IMPORTING i TYPE i EXPORTING out_speed TYPE i.
ENDCLASS.
*---------------------------------------------------------------------*
* 类的实现部分
*---------------------------------------------------------------------*
CLASS car IMPLEMENTATION.
METHOD accelerate.
speed = speed + i.
out_speed = speed.
ENDMETHOD.
METHOD show_speed.
cl_demo_output=>display( speed ).
ENDMETHOD.
ENDCLASS.
完整程序
REPORT ztest_class_02_lhy.
*---------------------------------------------------------------------*
* 类定义
*---------------------------------------------------------------------*
CLASS car DEFINITION.
PUBLIC SECTION.
DATA: speed TYPE i,
weight TYPE i.
METHODS:show_speed,
accelerate IMPORTING i TYPE i EXPORTING out_speed TYPE i.
ENDCLASS.
*---------------------------------------------------------------------*
* 类的实现部分
*---------------------------------------------------------------------*
CLASS car IMPLEMENTATION.
METHOD accelerate.
speed = speed + i.
out_speed = speed.
ENDMETHOD.
METHOD show_speed.
cl_demo_output=>display( speed ).
ENDMETHOD.
ENDCLASS.
DATA obj TYPE REF TO car. "定义对象
START-OF-SELECTION.
DATA s TYPE i.
DATA outspeed TYPE i.
s = 1.
CREATE OBJECT obj. "创建对象
CALL METHOD obj->accelerate
EXPORTING i = s
IMPORTING out_speed = outspeed.
cl_demo_output=>write( outspeed ).
"WRITE:'speed:', speed.
CALL METHOD obj->show_speed( ).
创建对象obj，类型是参考car类，调用accelerate方法，传入参数s，用outspeed接受方法传出的out_speed的值。方法定义时用的是IMPORTING，调用时使用EXPORTING，定义使用EXPORTING，调用时使用IMPORTING。
执行结果
RETURNING与RECEIVING
如果省略CALL METHOD，则一定要加上括号形式；如果通过CALL METHOD来调用，则括号可加可不加
RECEIVING：用来接收METHODS /CLASS-METHODS 中RETURNING选项返回的值
*&---------------------------------------------------------------------*
*& Report ZTEST_CLASS_02_LHY
*&---------------------------------------------------------------------*
*& 类型：Report
*& 创建人：LiuHongyu
*& 创建时间：2024.1.22
*& 描述：面对对象学习测试
************************************************************************
* Changed History
*------------- ------------- --------------- ---------------
* 版本 修改人 修改时间 修改描述
*------------- ------------- --------------- ---------------
* N LiuHongyu 2024.1.22 创建
*------------- ------------- --------------- ---------------
************************************************************************
*&---------------------------------------------------------------------*
REPORT ztest_class_02_lhy.
*---------------------------------------------------------------------*
* 类定义
*---------------------------------------------------------------------*
CLASS car DEFINITION.
PUBLIC SECTION.
DATA: speed TYPE i,
weight TYPE i.
METHODS:show_speed,
accelerate IMPORTING i TYPE i EXPORTING out_speed TYPE i,
decelerate IMPORTING i TYPE i
EXPORTING out_speed TYPE i
CHANGING de_speed TYPE i
RETURNING VALUE(r1) TYPE i.
ENDCLASS.
*---------------------------------------------------------------------*
* 类的实现部分
*---------------------------------------------------------------------*
CLASS car IMPLEMENTATION.
METHOD accelerate.
speed = speed + i.
out_speed = speed.
ENDMETHOD.
METHOD decelerate .
speed = speed - i.
out_speed = speed.
speed = speed - de_speed.
de_speed = de_speed + 1.
r1 = out_speed.
ENDMETHOD.
METHOD show_speed.
cl_demo_output=>display( speed ).
ENDMETHOD.
ENDCLASS.
DATA obj TYPE REF TO car. "定义对象
START-OF-SELECTION.
DATA s TYPE i.
DATA: de_i TYPE i,
de_out_speed TYPE i,
de_de_speed TYPE i,
de_r1 TYPE i.
DATA outspeed TYPE i.
de_i = 1.
de_de_speed = 7.
s = 10.
CREATE OBJECT obj. "创建对象
CALL METHOD obj->accelerate
EXPORTING i = s
IMPORTING out_speed = outspeed.
cl_demo_output=>write( '调用accelerate加速方法：' ).
cl_demo_output=>write( outspeed ). "10
"WRITE:'speed:', speed.
CALL METHOD obj->show_speed( ). "10
cl_demo_output=>write( '调用decelerate减速方法：' ).
* CALL METHOD obj->decelerate
* EXPORTING i = de_i
* IMPORTING out_speed = de_out_speed
* CHANGING de_speed = de_de_speed "CHANGING：既可以传入 也可以传出
* RECEIVING r1 = de_r1. "RECEIVING：接收
de_r1 = obj->decelerate(
EXPORTING i = de_i
IMPORTING out_speed = de_out_speed
CHANGING de_speed = de_de_speed ). "CHANGING：既可以传入 也可以传出
"RECEIVING r1 = de_r1. "RECEIVING：接收
cl_demo_output=>write( de_out_speed ). "9
cl_demo_output=>write( de_de_speed ). "8
cl_demo_output=>write( de_r1 ). "9
obj->show_speed( ).
接收decelerate方法返回的变量r1
方法1
de_r1接收decelerate方法的值：
de_r1 = obj->decelerate(
EXPORTING i = de_i
IMPORTING out_speed = de_out_speed
CHANGING de_speed = de_de_speed ). "CHANGING：既可以传入 也可以传出
方法2
使用CALL METHOD来调用decelerate方法，将dei传入方法，deout_speed接收，用r1来接收RETURNING的值：
CALL METHOD obj->decelerate
EXPORTING i = de_i
IMPORTING out_speed = de_out_speed
CHANGING de_speed = de_de_speed "CHANGING：既可以传入 也可以传出
RECEIVING r1 = de_r1. "RECEIVING：接收
执行结果
继承
基类的定义和实现
* 基类
CLASS base DEFINITION.
PUBLIC SECTION.
DATA: length TYPE i, "长
width TYPE i, "宽
high TYPE i, "高
area TYPE p DECIMALS 2, "面积
volumes TYPE p DECIMALS 2. "体积
METHODS: calculate_area IMPORTING l TYPE i w TYPE i h TYPE i
EXPORTING a TYPE p.
PRIVATE SECTION.
DATA: p_area TYPE p DECIMALS 2.
ENDCLASS.
* 基类实现
CLASS base IMPLEMENTATION.
METHOD calculate_area.
length = l.
width = w.
high = h.
area = ( length * width ) / 2.
p_area = area.
a = area.
cl_demo_output=>write( area ).
ENDMETHOD.
ENDCLASS.
子类的定义和实现
子类自己定义和实现了chcalculatearea方法，子类不能访问基类的私有变量，并重写了基类的calculate_area方法，重写要加上REDEFINITION关键字：
* 子类
CLASS child DEFINITION INHERITING FROM base.
PUBLIC SECTION.
CLASS-DATA: cl_child_area TYPE p DECIMALS 2.
METHODS:
calculate_area REDEFINITION, "REDEFINITION重写方法
ch_calculate_area IMPORTING l TYPE i w TYPE i h TYPE i
EXPORTING a TYPE p.
ENDCLASS.
CLASS child IMPLEMENTATION.
METHOD calculate_area."重写父类的方法
length = l.
width = w.
high = h.
area = ( length * width ) / 100.
cl_child_area = area.
"p_area = area.
a = area.
cl_demo_output=>write( area ).
ENDMETHOD.
METHOD ch_calculate_area.
length = l.
width = w.
high = h.
area = ( length * width ) / 5.
cl_child_area = area.
"p_area = area.
a = area.
cl_demo_output=>write( cl_child_area ).
ENDMETHOD.
ENDCLASS.
主程序调用
START-OF-SELECTION.
*&---------------------------Variable----------------------------------*
DATA: length TYPE i,
width TYPE i,
high TYPE i,
area TYPE p DECIMALS 2.
DATA base_obj TYPE REF TO base.
DATA ch_obj TYPE REF TO child.
CREATE OBJECT base_obj.
CREATE OBJECT ch_obj.
length = 9.
width = 3.
high = 6.
*&---------------------------Logic----------------------------------*
CALL METHOD base_obj->calculate_area "调用calculate_area方法
EXPORTING l = length
w = width
h = high
IMPORTING a = area.
WRITE:/, 'area:',area.
CALL METHOD ch_obj->ch_calculate_area "调用子类的方法
EXPORTING l = length
w = width
h = high
IMPORTING a = area.
WRITE:/, 'child_area:',area.
CALL METHOD ch_obj->calculate_area "调用父类的方法
EXPORTING l = length
w = width
h = high
IMPORTING a = area.
cl_demo_output=>display( ).
WRITE:/, 'child_area:',area.
执行效果
write打印：
，
构造函数constructor
定义构造函数constructor：
REPORT ztest_class_02_lhy.
*---------------------------------------------------------------------*
* car类定义
*---------------------------------------------------------------------*
CLASS car DEFINITION.
PUBLIC SECTION.
DATA: speed TYPE i,
weight TYPE i.
METHODS:show_speed,
accelerate IMPORTING i TYPE i EXPORTING out_speed TYPE i,
decelerate IMPORTING i TYPE i
EXPORTING out_speed TYPE i
CHANGING de_speed TYPE i
RETURNING VALUE(r1) TYPE i,
constructor. "构造函数
ENDCLASS.
*---------------------------------------------------------------------*
* car类的实现部分
*---------------------------------------------------------------------*
CLASS car IMPLEMENTATION.
METHOD accelerate.
speed = speed + i.
out_speed = speed.
ENDMETHOD.
METHOD decelerate .
speed = speed - i.
out_speed = speed.
speed = speed - de_speed.
de_speed = de_speed + 1.
r1 = out_speed.
ENDMETHOD.
METHOD show_speed.
cl_demo_output=>display( speed ).
ENDMETHOD.
METHOD constructor.
cl_demo_output=>display('constructor triggered').
ENDMETHOD.
ENDCLASS.
主程序
创建car类对象obj，调用accelerate方法，调用show_speed方法。
DATA obj TYPE REF TO car. "定义对象
START-OF-SELECTION.
DATA s TYPE i.
DATA: de_i TYPE i,
de_out_speed TYPE i,
de_de_speed TYPE i,
de_r1 TYPE i.
DATA outspeed TYPE i.
de_i = 1.
de_de_speed = 7.
s = 10.
CREATE OBJECT obj. "创建对象
CALL METHOD obj->accelerate
EXPORTING i = s
IMPORTING out_speed = outspeed.
cl_demo_output=>write( '调用accelerate加速方法：' ).
cl_demo_output=>write( outspeed ). "10
"WRITE:'speed:', speed.
CALL METHOD obj->show_speed( ). "10
执行效果
执行完之后，弹出两个弹窗
第一个：
第二个：
重写和super关键字
* 基类
CLASS base DEFINITION.
PUBLIC SECTION.
DATA: length TYPE i, "长
width TYPE i, "宽
high TYPE i, "高
area TYPE p DECIMALS 2, "面积
volumes TYPE p DECIMALS 2. "体积
METHODS: calculate_area IMPORTING l TYPE i w TYPE i h TYPE i
EXPORTING a TYPE p.
PRIVATE SECTION.
DATA: p_area TYPE p DECIMALS 2.
ENDCLASS.
* 基类实现
CLASS base IMPLEMENTATION.
METHOD calculate_area.
length = l.
width = w.
high = h.
area = ( length * width ) / 2.
p_area = area.
a = area.
cl_demo_output=>write( area ).
ENDMETHOD.
ENDCLASS.
* 子类
CLASS child DEFINITION INHERITING FROM base.
PUBLIC SECTION.
CLASS-DATA: cl_child_area TYPE p DECIMALS 2.
METHODS:
calculate_area REDEFINITION, "REDEFINITION重写方法
ch_calculate_area IMPORTING l TYPE i w TYPE i h TYPE i
EXPORTING a TYPE p.
ENDCLASS.
CLASS child IMPLEMENTATION.
METHOD calculate_area."重写父类的方法
CALL METHOD super->calculate_area "使用super调用父类的方法
EXPORTING
l = length
w = width
h = high
IMPORTING
a = area.
cl_demo_output=>write( '重写父类的方法后，通过super调用父类的方法获取的area:' ).
cl_demo_output=>write( area ).
* length = l.
* width = w.
* high = h.
* area = ( length * width ) / 100.
* cl_child_area = area.
* "p_area = area.
* a = area.
* cl_demo_output=>write( area ).
ENDMETHOD.
METHOD ch_calculate_area.
length = l.
width = w.
high = h.
area = ( length * width ) / 5.
cl_child_area = area.
"p_area = area.
a = area.
cl_demo_output=>write( cl_child_area ).
ENDMETHOD.
ENDCLASS.
主程序
DATA obj TYPE REF TO car. "定义对象
START-OF-SELECTION.
*&---------------------------Variable----------------------------------*
DATA: length TYPE i,
width TYPE i,
high TYPE i,
area TYPE p DECIMALS 2.
DATA base_obj TYPE REF TO base.
DATA ch_obj TYPE REF TO child.
CREATE OBJECT base_obj.
CREATE OBJECT ch_obj.
length = 9.
width = 3.
high = 6.
*&---------------------------Logic----------------------------------*
CALL METHOD base_obj->calculate_area "调用calculate_area方法
EXPORTING l = length
w = width
h = high
IMPORTING a = area.
WRITE:/, 'area:',area.
CALL METHOD ch_obj->ch_calculate_area "调用子类的方法
EXPORTING l = length
w = width
h = high
IMPORTING a = area.
WRITE:/, 'child_area:',area.
CALL METHOD ch_obj->calculate_area "调用父类的方法
EXPORTING l = length
w = width
h = high
IMPORTING a = area.
cl_demo_output=>display( ).
WRITE:/, 'child_area:',area.
完整程序*&---------------------------------------------------------------------*
*& Report ZTEST_CLASS_02_LHY
*&---------------------------------------------------------------------*
*& 类型：Report
*& 创建人：LiuHongyu
*& 创建时间：2024.1.22
*& 描述：面对对象学习测试
************************************************************************
* Changed History
*------------- ------------- --------------- ---------------
* 版本 修改人 修改时间 修改描述
*------------- ------------- --------------- ---------------
* N LiuHongyu 2024.1.22 创建
*------------- ------------- --------------- ---------------
************************************************************************
*&---------------------------------------------------------------------*
REPORT ztest_class_02_lhy.
*---------------------------------------------------------------------*
* car类定义
*---------------------------------------------------------------------*
CLASS car DEFINITION.
PUBLIC SECTION.
DATA: speed TYPE i,
weight TYPE i.
METHODS:show_speed,
accelerate IMPORTING i TYPE i EXPORTING out_speed TYPE i,
decelerate IMPORTING i TYPE i
EXPORTING out_speed TYPE i
CHANGING de_speed TYPE i
RETURNING VALUE(r1) TYPE i,
constructor. "构造函数
ENDCLASS.
*---------------------------------------------------------------------*
* car类的实现部分
*---------------------------------------------------------------------*
CLASS car IMPLEMENTATION.
METHOD accelerate.
speed = speed + i.
out_speed = speed.
ENDMETHOD.
METHOD decelerate .
speed = speed - i.
out_speed = speed.
speed = speed - de_speed.
de_speed = de_speed + 1.
r1 = out_speed.
ENDMETHOD.
METHOD show_speed.
cl_demo_output=>display( speed ).
ENDMETHOD.
METHOD constructor.
cl_demo_output=>display('Constructor Triggered').
ENDMETHOD.
ENDCLASS.
* 基类
CLASS base DEFINITION.
PUBLIC SECTION.
DATA: length TYPE i, "长
width TYPE i, "宽
high TYPE i, "高
area TYPE p DECIMALS 2, "面积
volumes TYPE p DECIMALS 2. "体积
METHODS: calculate_area IMPORTING l TYPE i w TYPE i h TYPE i
EXPORTING a TYPE p.
PRIVATE SECTION.
DATA: p_area TYPE p DECIMALS 2.
ENDCLASS.
* 基类实现
CLASS base IMPLEMENTATION.
METHOD calculate_area.
length = l.
width = w.
high = h.
area = ( length * width ) / 2.
p_area = area.
a = area.
cl_demo_output=>write( area ).
ENDMETHOD.
ENDCLASS.
* 子类
CLASS child DEFINITION INHERITING FROM base.
PUBLIC SECTION.
CLASS-DATA: cl_child_area TYPE p DECIMALS 2.
METHODS:
calculate_area REDEFINITION, "REDEFINITION重写方法
ch_calculate_area IMPORTING l TYPE i w TYPE i h TYPE i
EXPORTING a TYPE p.
ENDCLASS.
CLASS child IMPLEMENTATION.
METHOD calculate_area."重写父类的方法
CALL METHOD super->calculate_area "使用super调用父类的方法
EXPORTING
l = length
w = width
h = high
IMPORTING
a = area.
cl_demo_output=>write( '重写父类的方法后，通过super调用父类的方法获取的area:' ).
cl_demo_output=>write( area ).
* length = l.
* width = w.
* high = h.
* area = ( length * width ) / 100.
* cl_child_area = area.
* "p_area = area.
* a = area.
* cl_demo_output=>write( area ).
ENDMETHOD.
METHOD ch_calculate_area.
length = l.
width = w.
high = h.
area = ( length * width ) / 5.
cl_child_area = area.
"p_area = area.
a = area.
cl_demo_output=>write( cl_child_area ).
ENDMETHOD.
ENDCLASS.
DATA obj TYPE REF TO car. "定义对象
START-OF-SELECTION.
*&---------------------------Variable----------------------------------*
DATA: length TYPE i,
width TYPE i,
high TYPE i,
area TYPE p DECIMALS 2.
DATA base_obj TYPE REF TO base.
DATA ch_obj TYPE REF TO child.
CREATE OBJECT base_obj.
CREATE OBJECT ch_obj.
length = 9.
width = 3.
high = 6.
*&---------------------------Logic----------------------------------*
CALL METHOD base_obj->calculate_area "调用calculate_area方法
EXPORTING l = length
w = width
h = high
IMPORTING a = area.
WRITE:/, 'area:',area.
CALL METHOD ch_obj->ch_calculate_area "调用子类的方法
EXPORTING l = length
w = width
h = high
IMPORTING a = area.
WRITE:/, 'child_area:',area.
CALL METHOD ch_obj->calculate_area "调用父类的方法
EXPORTING l = length
w = width
h = high
IMPORTING a = area.
cl_demo_output=>display( ).
WRITE:/, 'child_area:',area.
* DATA s TYPE i.
* DATA: de_i TYPE i,
* de_out_speed TYPE i,
* de_de_speed TYPE i,
* de_r1 TYPE i.
* DATA outspeed TYPE i.
* de_i = 1.
* de_de_speed = 7.
* s = 10.
* CREATE OBJECT obj. "创建对象
* CALL METHOD obj->accelerate
* EXPORTING i = s
* IMPORTING out_speed = outspeed.
* cl_demo_output=>write( '调用accelerate加速方法：' ).
* cl_demo_output=>write( outspeed ). "10
* "WRITE:'speed:', speed.
* CALL METHOD obj->show_speed( ). "10
* cl_demo_output=>write( '调用decelerate减速方法：' ).
** CALL METHOD obj->decelerate
** EXPORTING i = de_i
** IMPORTING out_speed = de_out_speed
** CHANGING de_speed = de_de_speed "CHANGING：既可以传入 也可以传出
** RECEIVING r1 = de_r1. "RECEIVING：接收
* de_r1 = obj->decelerate(
* EXPORTING i = de_i
* IMPORTING out_speed = de_out_speed
* CHANGING de_speed = de_de_speed ). "CHANGING：既可以传入 也可以传出
* "RECEIVING r1 = de_r1. "RECEIVING：接收
* cl_demo_output=>write( de_out_speed ). "9
* cl_demo_output=>write( de_de_speed ). "8
* cl_demo_output=>write( de_r1 ). "9
* obj->show_speed( ).
OPTIONAL 和 DEFAULT
OPTIONAL
OPTIONAL：表示参数是可选的，在调用时是可选择是否传参的，你可以传递参数，也可以不传递参数。
DEFAULT
DEFAULT：表示参数的有默认值的，是否传递参数也是可选的，你可以不传递参数，此时的默认值是定义时的默认值。如果传递参数，那么就使用你传入的值。
程序名：ZTESTCLASS03_LHY
如果使用DEFAULT，需要设置默认值：
设置为1：
car类的定义和实现
*&---------------------------------------------------------------------*
*& Report ZTEST_CLASS_03_LHY
*&---------------------------------------------------------------------*
*&
*&---------------------------------------------------------------------*
REPORT ztest_class_03_lhy.
*---------------------------------------------------------------------*
* car类定义
*---------------------------------------------------------------------*
CLASS car DEFINITION.
PUBLIC SECTION.
DATA: speed TYPE i,
weight TYPE i.
METHODS: fun1 IMPORTING a TYPE i OPTIONAL,
fun2 IMPORTING b TYPE i DEFAULT 1.
endclass.
*---------------------------------------------------------------------*
* car类的实现部分
*---------------------------------------------------------------------*
CLASS car IMPLEMENTATION.
METHOD fun1.
speed = a.
cl_demo_output=>write( speed ).
ENDMETHOD.
METHOD fun2.
weight = b.
cl_demo_output=>write( weight ).
ENDMETHOD.
ENDCLASS.
不传值时的主程序
START-OF-SELECTION.
DATA a TYPE REF TO car.
CREATE OBJECT a.
CALL METHOD a->fun1.
CALL METHOD a->fun2.
cl_demo_output=>display( ).
传值时的主程序
START-OF-SELECTION.
DATA a TYPE REF TO car.
CREATE OBJECT a.
CALL METHOD a->fun1 EXPORTING a = 1000.
CALL METHOD a->fun2 EXPORTING b = 3.
cl_demo_output=>display( ).
运行结果
不传值时
不向方法fun1和fun2传值，效果如下：
传值时
向fun1传递参数1000，向fun2传递3时，效果如下：
完整程序
*&---------------------------------------------------------------------*
*& Report ZTEST_CLASS_03_LHY
*&---------------------------------------------------------------------*
*&
*&---------------------------------------------------------------------*
REPORT ztest_class_03_lhy.
*---------------------------------------------------------------------*
* car类定义
*---------------------------------------------------------------------*
CLASS car DEFINITION.
PUBLIC SECTION.
DATA: speed TYPE i,
weight TYPE i.
METHODS: fun1 IMPORTING a TYPE i OPTIONAL,
fun2 IMPORTING b TYPE i DEFAULT 1.
endclass.
*---------------------------------------------------------------------*
* car类的实现部分
*---------------------------------------------------------------------*
CLASS car IMPLEMENTATION.
METHOD fun1.
speed = a.
cl_demo_output=>write( speed ).
ENDMETHOD.
METHOD fun2.
weight = b.
cl_demo_output=>write( weight ).
ENDMETHOD.
ENDCLASS.
START-OF-SELECTION.
DATA a TYPE REF TO car.
CREATE OBJECT a.
CALL METHOD a->fun1 EXPORTING a = 1000.
CALL METHOD a->fun2 EXPORTING b = 3.
* CALL METHOD a->fun1.
* CALL METHOD a->fun2.
cl_demo_output=>display( ).
接口-INTERFACE
接口定义
接口保证这些类外部看起来具有一致性标准化的接口, 又可以在不同的类内部使用不同的实现方法。
在接口定义内部可以声明的成员与类中的成员相同, 但无需注明具体的可见性, 因为具体类中实现的所有接口组件均为公有成员. 同时, 接口定义中也只包含成员声明部分, 而具体的实现也将在具体类中进行.
*---------------------------------------------------------------------*
* r_run接口的定义
*---------------------------------------------------------------------*
INTERFACE i_run.
"INTERFACE内的都是公共的，不用刻意说明限制范围：PUBLIC / PROTECT / PRIVATE
DATA speed TYPE i.
CLASS-DATA cl_speed TYPE i.
METHODS: acc1 IMPORTING a TYPE i.
ENDINTERFACE.
报错
acc1没有被识别到，因为没有加上i_run1~：来指明接口
实现接口方法
加上i_run~接口：
调用接口方法
通过类访问接口方法
使用a->i_runacc1来调用实现的接口的方法，需要使用对象->接口名方法名：
*&---------------------------------------------------------------------*
*& Report ZTEST_CLASS_03_LHY
*&---------------------------------------------------------------------*
*&
*&---------------------------------------------------------------------*
REPORT ztest_class_03_lhy.
*---------------------------------------------------------------------*
* r_run接口的定义
*---------------------------------------------------------------------*
INTERFACE i_run.
"INTERFACE内的都是公共的，不用刻意说明限制范围：PUBLIC / PROTECT / PRIVATE
DATA speed TYPE i.
CLASS-DATA cl_speed TYPE i.
METHODS: acc1 IMPORTING a TYPE i.
ENDINTERFACE.
*---------------------------------------------------------------------*
* car类定义
*---------------------------------------------------------------------*
CLASS car DEFINITION.
PUBLIC SECTION.
DATA: speed TYPE i,
weight TYPE i.
METHODS: fun1 IMPORTING a TYPE i OPTIONAL,
fun2 IMPORTING b TYPE i DEFAULT 1.
INTERFACES i_run.
ENDCLASS.
*---------------------------------------------------------------------*
* car类的实现部分
*---------------------------------------------------------------------*
CLASS car IMPLEMENTATION.
METHOD fun1.
speed = a.
cl_demo_output=>write( speed ).
ENDMETHOD.
METHOD fun2.
weight = b.
cl_demo_output=>write( weight ).
ENDMETHOD.
METHOD i_run~acc1.
speed = speed * a.
cl_demo_output=>write( speed ).
ENDMETHOD.
ENDCLASS.
START-OF-SELECTION.
DATA a TYPE REF TO car.
CREATE OBJECT a.
CALL METHOD a->fun1 EXPORTING a = 1000.
CALL METHOD a->fun2 EXPORTING b = 3.
CALL METHOD a->i_run~acc1 EXPORTING a = 3. "a->i_run~acc1，需要使用对象->接口名~方法名
* CALL METHOD a->fun1.
* CALL METHOD a->fun2.
cl_demo_output=>display( ).
运行效果
第一个是调用fun1方法得到的speed，第二个是调用fun2方法得到的weight，第三个调用acc1方法得到的speed：
CALL METHOD a->i_run~acc1 EXPORTING a = 3. "a->i_run~acc1，需要使用对象->接口名~方法名
通过接口访问成员
CALL METHOD intf->acc1 EXPORTING a = 8.
完整程序
*&---------------------------------------------------------------------*
*& Report ZTEST_CLASS_03_LHY
*&---------------------------------------------------------------------*
*&
*&---------------------------------------------------------------------*
REPORT ztest_class_03_lhy.
*----------------------------------------------------------------------*
* r_run接口的定义
*---------------------------------------------------------------------*
INTERFACE i_run.
"INTERFACE内的都是公共的，不用刻意说明限制范围：PUBLIC / PROTECT / PRIVATE
DATA speed TYPE i.
CLASS-DATA cl_speed TYPE i.
METHODS: acc1 IMPORTING a TYPE i.
ENDINTERFACE.
*---------------------------------------------------------------------*
* car类定义
*---------------------------------------------------------------------*
CLASS car DEFINITION.
PUBLIC SECTION.
DATA: speed TYPE i,
weight TYPE i.
METHODS: fun1 IMPORTING a TYPE i OPTIONAL,
fun2 IMPORTING b TYPE i DEFAULT 1.
INTERFACES i_run.
ENDCLASS.
*---------------------------------------------------------------------*
* car类的实现部分
*---------------------------------------------------------------------*
CLASS car IMPLEMENTATION.
METHOD fun1.
speed = a.
cl_demo_output=>write( speed ).
ENDMETHOD.
METHOD fun2.
weight = b.
cl_demo_output=>write( weight ).
ENDMETHOD.
METHOD i_run~acc1.
speed = speed * a.
cl_demo_output=>write( speed ).
ENDMETHOD.
ENDCLASS.
START-OF-SELECTION.
DATA a TYPE REF TO car.
DATA intf TYPE REF TO i_run."intf接口对象
CREATE OBJECT intf TYPE car. "通过挂靠在类上来
CREATE OBJECT a.
CALL METHOD intf->acc1 EXPORTING a = 8.
CALL METHOD a->fun1 EXPORTING a = 1000.
CALL METHOD a->fun2 EXPORTING b = 3.
CALL METHOD a->i_run~acc1 EXPORTING a = 3. "a->i_run~acc1，需要使用对象->接口名~方法名
* CALL METHOD a->fun1.
* CALL METHOD a->fun2.
cl_demo_output=>display( ).
运行效果
第一个SPEED是通过intf接口变量调用acc1方法输出的：
接口引用间赋值
接口类型不能赋值给非object类的类
START-OF-SELECTION.
DATA a TYPE REF TO car.
DATA intf TYPE REF TO i_run."intf接口对象
DATA myc1 TYPE REF TO object."类object是所有类的父类，且不需实例（create OBJECT会报错)
CREATE OBJECT intf TYPE car. "通过挂靠在类上
CREATE OBJECT a.
"a = intf.
intf = a.
myc1 = intf. "接口可以赋值给object类的对象
CALL METHOD intf->acc1 EXPORTING a = 8.
CALL METHOD a->fun1 EXPORTING a = 1000.
CALL METHOD a->fun2 EXPORTING b = 3.
CALL METHOD a->i_run~acc1 EXPORTING a = 3. "a->i_run~acc1，需要使用对象->接口名~方法名
* 类赋值给接口
intf = a."正常
intf = myc1.
报错
接口类型不能赋值给非object类的类，只能赋值给object类型的：
例如：
START-OF-SELECTION.
DATA a TYPE REF TO car.
DATA intf TYPE REF TO i_run."intf接口对象
DATA intf2 TYPE REF TO i_run.
DATA myc1 TYPE REF TO object."类object是所有类的父类，且不需实例（create OBJECT会报错)
CREATE OBJECT intf TYPE car. "通过挂靠在类上来
CREATE OBJECT intf2 TYPE car.
CREATE OBJECT a.
"a = intf.
intf = a.
myc1 = intf. "接口可以赋值给object类的对象
object类型不能赋值成接口类型
转换成car类型是不会报错的：
START-OF-SELECTION.
DATA a TYPE REF TO car.
DATA intf TYPE REF TO i_run."intf接口对象
DATA myc1 TYPE REF TO object."类object是所有类的父类，且不需实例（create OBJECT会报错)
CREATE OBJECT intf TYPE car. "通过挂靠在类上
CREATE OBJECT a.
"a = intf.
intf = a.
myc1 = intf. "接口可以赋值给object类的对象
CALL METHOD intf->acc1 EXPORTING a = 8.
CALL METHOD a->fun1 EXPORTING a = 1000.
CALL METHOD a->fun2 EXPORTING b = 3.
CALL METHOD a->i_run~acc1 EXPORTING a = 3. "a->i_run~acc1，需要使用对象->接口名~方法名
* 类赋值给接口
intf = a."正常
intf = myc1.
intf = myc1.会报错。object类型的对象不能赋值给i_run接口类型，需要使用 ?= 强制转换符进行转换。
?= 类、接口等类型的向下类型转换
一、概念
向上转型是指将子类的实例赋值给父类类型的变量。 向下转型是指将父类的实例赋值给子类类型的变量。
二、向上转型
1、向上转型后父类的引用所指向的属性是父类的属性。 2、如果子类重写了父类的方法，那么父类引用指向的或者调用的方法是子类的方法，这个叫动态绑定（实现多态）。 3、父类引用不能调用子类自己的方法。 4、向上转型会丢失子类的新增方法，同时会保留子类重写的方法。
三、向下转型
1、编译时需要强制类型转换，father前面的必须添加（Son）。 2、运行时会出现java.lang.ClassCastException错误，可使用instanceof来避免出错此类错误。 3、向下转型可以得到子类的所有方法（包含父类的方法）。
?= 和 =
?= 向下类型转换（Down Cast ）
= 向上类型转换（Up Cast ）
1、向上、向下中的上下，可以理解成父类和子类。
2、向上转型（up-cast 或者 narrowing cast）指子类型引用实例化父类型对象，这样父类引用指向子类引用。这样之后父类的引用是访问不了子类的变量和方法的。用narrowing理解好点。
3、向下转型（down-cast 或者 widening cast） 父类型的引用来实例化子类型对象。这样之后子类型可以访问子类型所有方法，具体后面讲到。必须用 ?= 或者move…?to… (cast operator)
• 向上转型是把子类引用实例化父类对象。
• 向下转型是把父类引用实例化子类对象。
因为父亲有的，儿子肯定也有。所以可以直接转型。
loson = lofather.(向上)
但是儿子有的，父亲不一定有。所以需要强制转型。
lofather ?= loson.(向下)
事件
参考文章
https://blog.csdn.net/m0_61425806/article/details/128902242
• 用于捕获某类对象状态的改变来触发事件的方法，并进行处理。
• 事件是没有继承关系的类之间可以互相调用彼此方法的特殊方法。
• 当需要关联两个互不关联的类时，需要通过定义事件来实现
声明事件
事件可以在类或接口的声名部分进行声明.
定义：可以在类或接口中进行声明：
EVENTS|CLASS-EVENTS evt
EXPORTING … VALUE(p1)TYPE type|LIKE f [OPTIONAL|DEFAULT g] …
例：
EVENTS mod_10 EXPORTING VALUE(p_data) TYPE i.
实例事件中包含一个隐含参数SENDER，该参数的类型为触发时间的类或接口对象引用。
触发事件
非静态事件只能在非静态方法中触发，而不能在静态方法中触发；而静态事件即可在静态也可在非静态方法中进行触发，或者反过来说：实例方法既可触发静态事件，也可触发非静态事件，但静态方法就只能触发静态事件。
RAISE EVENT mod_10 EXPORTING p_data = t_data."触发事件
接收事件
事件需要通过方法捕获事件并进行处理, 必须首先为该事件定义一个事件处理方法, 然后在运行时为该事件进行注册。
METHODS write_data FOR EVENT mod_10 OF cl_data IMPORTING p_data."接收事件
注册事件
要使事件处理方法能够对事件进行响应，必须在运行时为相关事件注册该方法：
SET HANDLER cl_handl->write_data FOR cl_event."注册事件，才可以进行两个类之间的变量传值
对于实例事件, 在进行处理之前必须在注册语句中使用附加项 FOR 指定希望注册到的对象.
可以指定一个单独的对象作为事件触发者。
SET HANDLER ... hi ... FOR ref.
或者使用 FOR ALL INSTANCES 附加项为处理器注册所有可以触发该事件的实例；
SET HANDLER ... hi ... FOR ALL INSTANCES.
该注册过程可以作用于目前尚未被创建的实例。
SET HANDLER ... hi ...
对于静态事件, 则不能使用 FOR 附加项；
示例
程序名：ZTESTCLASS03_LHY
*---------------------------------------------------------------------*
* cl_data类定义
*---------------------------------------------------------------------*
CLASS cl_data DEFINITION.
PUBLIC SECTION. "公有
METHODS add_data.
EVENTS mod_10 EXPORTING VALUE(p_data) TYPE i."定义事件
PRIVATE SECTION. "私有
DATA t_data TYPE i.
ENDCLASS.
*---------------------------------------------------------------------*
* cl_data类实现
*---------------------------------------------------------------------*
CLASS cl_data IMPLEMENTATION.
METHOD add_data.
DATA gv_data TYPE i.
t_data = t_data + 1.
gv_data = t_data MOD 10."取余
IF gv_data = 0."如果余数等于0
RAISE EVENT mod_10 EXPORTING p_data = t_data."触发事件
ENDIF.
ENDMETHOD.
ENDCLASS.
*---------------------------------------------------------------------*
* lcl_handler类定义
*---------------------------------------------------------------------*
CLASS lcl_handler DEFINITION.
PUBLIC SECTION.
METHODS write_data FOR EVENT mod_10 OF cl_data IMPORTING p_data."接收事件
ENDCLASS.
*---------------------------------------------------------------------*
* lcl_handler类实现
*---------------------------------------------------------------------*
CLASS lcl_handler IMPLEMENTATION.
METHOD write_data.
WRITE:/ p_data.
ENDMETHOD.
ENDCLASS.
DATA cl_event TYPE REF TO cl_data."创建对象
DATA cl_handl TYPE REF TO lcl_handler. "创建对象
START-OF-SELECTION.
CREATE OBJECT cl_handl."实例化
CREATE OBJECT cl_event. "实例化
SET HANDLER cl_handl->write_data FOR cl_event."注册事件，才可以进行两个类之间的变量传值
DO 50 TIMES.
CALL METHOD cl_event->add_data.
ENDDO.
运行效果
