Headfirst设计模式的C++实现——命令模式(Command)

先看如果不用命令模式的实现：

light.h

 1 #ifndef _LIGHT_H_
 2 #define _LIGHT_H
 3 
 4 #include <iostream>
 5 
 6 class LIGHT {
 7 public:
 8     void on() { std::cout << "light is on" << std::endl; }
 9     void off() { std::cout << "light is off" << std::endl; }
10 };
11 
12 #endif

tv.h

 1 #ifndef _TV_H_
 2 #define _TV_H_
 3 
 4 #include <iostream>
 5 
 6 class TV {
 7 public:
 8     void open() { std::cout << "TV is opened" << std::endl; }
 9     void close() { std::cout << "TV is closed" << std::endl; }
10 };
11 #endif

remote.h

 1 #ifndef _REMOTE_H_
 2 #define _REMOTE_H_
 3 
 4 #include <string>
 5 #include <iostream>
 6 #include "tv.h"
 7 #include "light.h"
 8 
 9 class REMOTE {
10 public:
11     void set(int slot, const std::string& device) {
12         if ( slot < MAX_SLOT_NUM ) {
13             all_device[slot] = device;
14         }
15     }
16 
17     void press_on_button(int slot) {
18         if ( slot >= MAX_SLOT_NUM ) {
19             return;    
20         }
21         if ( all_device[slot] == "" ) {
22             std::cout << "slot " << slot << " is empty" << std::endl;
23         }
24         else {
25             if ( "TV" == all_device[slot] ) {
26                 TV tv;
27                 tv.open();
28             }
29             else if ( "LIGHT" == all_device[slot] ) {
30                 LIGHT light;
31                 light.on();
32             }
33             else {
34                 std::cout << "invalid type" << std::endl;
35             }
36         }
37     }
38 
39     void press_off_button(int slot) {
40         if ( slot >= MAX_SLOT_NUM ) {
41             return;    
42         }
43         if ( all_device[slot] == "" ) {
44             std::cout << "slot " << slot << " is empty" << std::endl;
45         }
46         else {
47             if ( "TV" == all_device[slot] ) {
48                 TV tv;
49                 tv.close();
50             }
51             else if ( "LIGHT" == all_device[slot] ) {
52                 LIGHT light;
53                 light.off();
54             }
55             else {
56                 std::cout << "invalid type" << std::endl;
57             }
58 
59         }
60     }
61 private:
62     const static int MAX_SLOT_NUM = 7;
63     std::string all_device[MAX_SLOT_NUM];
64 };
65 
66 #endif

main.cpp

1 #include "remote.h"
2 int main() {
3     REMOTE remote;
4     remote.set(0, "TV");
5     remote.set(1, "LIGHT");
6     remote.press_on_button(0);
7     remote.press_off_button(1);
8     remote.press_on_button(2);    
9 }

再看看使用命令模式的实现

light.h和tv.h不变

command.h

1 #ifndef _COMMAND_H_
2 #define _COMMAND_H_
3 
4 class COMMAND {
5 public:
6     virtual void execute() = 0;
7 };
8 
9 #endif

light_on_command.h

 1 #ifndef _LIGHT_ON_COMMAND_H_
 2 #define _LIGHT_ON_COMMAND_H_
 3 
 4 #include "command.h"
 5 #include "light.h"
 6 
 7 class LIGHT_ON_COMMAND : public COMMAND {
 8 private:
 9     LIGHT &light;
10 public:
11     LIGHT_ON_COMMAND( LIGHT &_light ) : light(_light) {}
12     void execute() { light.on(); }
13 };
14 
15 #endif

light_off_command.h

 1 #ifndef _LIGHT_OFF_COMMAND_H_
 2 #define _LIGHT_OFF_COMMAND_H_
 3 
 4 #include "command.h"
 5 #include "light.h"
 6 
 7 class LIGHT_OFF_COMMAND : public COMMAND {
 8 private:
 9     LIGHT &light;
10 public:
11     LIGHT_OFF_COMMAND( LIGHT &_light ) : light(_light) {}
12     void execute() { light.off(); }
13 };
14 
15 #endif

tv_on_command.h

 1 #ifndef _TV_ON_COMMAND_H_
 2 #define _Tv_ON_COMMAND_H_
 3 
 4 #include "command.h"
 5 #include "tv.h"
 6 
 7 class TV_ON_COMMAND : public COMMAND {
 8 private:
 9     TV &tv;
10 public:
11     TV_ON_COMMAND( TV&_tv) : tv(_tv) {}
12     void execute() { tv.open(); }
13 };
14 
15 #endif

tv_off_command.h

 1 #ifndef _TV_OFF_COMMAND_H_
 2 #define _TV_OFF_COMMAND_H_
 3 
 4 #include "command.h"
 5 #include "tv.h"
 6 
 7 class TV_OFF_COMMAND : public COMMAND {
 8 private:
 9     TV &tv;
10 public:
11     TV_OFF_COMMAND( TV&_tv) : tv(_tv) {}
12     void execute() { tv.close(); }
13 };
14 
15 #endif

remote.h

 1 #ifndef _REMOTE_H_
 2 #define _REMOTE_H_
 3 
 4 #include "command.h"
 5 #include <iostream>
 6 
 7 class REMOTE {
 8 public:
 9     REMOTE() {
10         for ( int i = 0; i < MAX_SLOT_NUM; i++ ) {
11             on_commands[i] = NULL;
12             off_commands[i] = NULL;
13         }
14     }
15 
16     void set(int slot, COMMAND& on_command, COMMAND& off_command) {
17         if ( slot < MAX_SLOT_NUM ) {
18             on_commands[slot] = &on_command;
19             off_commands[slot] = &off_command;
20         }
21     }
22 
23     void press_on_button(int slot) {
24         if ( slot < MAX_SLOT_NUM ) {
25             if ( NULL != on_commands[slot] ) {
26                 on_commands[slot]->execute();
27             }
28             else {
29                 std::cout << "slot " << slot << " is empty" << std::endl;
30             }
31         }
32     }
33 
34     void press_off_button(int slot) {
35         if ( slot < MAX_SLOT_NUM ) {
36             if ( NULL != off_commands[slot] ) {
37                 off_commands[slot]->execute();
38             }
39             else {
40                 std::cout << "slot " << slot << " is empty" << std::endl;
41             }
42         }
43     }
44 private:
45     const static int MAX_SLOT_NUM = 7;
46     COMMAND *on_commands[MAX_SLOT_NUM];
47     COMMAND *off_commands[MAX_SLOT_NUM];
48 };
49 
50 #endif

main.cpp

 1 #include "remote.h"
 2 #include "tv_on_command.h"
 3 #include "tv_off_command.h"
 4 #include "light_on_command.h"
 5 #include "light_off_command.h"
 6 
 7 int main() {
 8     REMOTE remote;
 9 
10     TV tv;
11     TV_ON_COMMAND tv_on_command(tv);
12     TV_OFF_COMMAND tv_off_command(tv);
13     remote.set(0, tv_on_command, tv_off_command);
14 
15     LIGHT light;
16     LIGHT_ON_COMMAND light_on_command(light);
17     LIGHT_OFF_COMMAND light_off_command(light);
18     remote.set(1, light_on_command, light_off_command);
19 
20     remote.press_on_button(0);
21     remote.press_off_button(1);
22     remote.press_on_button(2);    
23 }

 

posted @ 2016-04-27 22:42  Ren.Yu  阅读(588)  评论(0)  编辑  收藏  举报