2.5 隐藏委托关系

【1】源代码

 1 #include <QString>
 2 
 3 class Department;
 4 class Person
 5 {
 6 public:
 7     QString getName()
 8     {
 9         return m_name;
10     }
11     void setName(QString name)
12     {
13         m_name = name;
14     }
15 
16     Department* get_department()
17     {
18         return m_department; // 获取部门对象
19     }
20 
21     void set_department(Department *department)
22     {
23         m_department = department;
24     }
25 
26 private:
27     QString m_name;
28     Department *m_department;
29 };
30 
31 class Department
32 {
33 public:
34     QString getCode()
35     {
36         return m_code;
37     }
38     void setCode(QString code)
39     {
40         m_code = code;
41     }
42     Person get_manager()
43     {
44         return m_manager; // 获取经理人
45     }
46     void set_manager(Person manager)
47     {
48         m_manager = manager;
49     }
50 
51 private:
52     QString m_code;
53     Person m_manager;
54 };
55 
56 int main(int argc, char *argv[])
57 {
58     QCoreApplication a(argc, argv);
59 
60     Person person;
61     QString strName = person.get_department()->get_manager().getName(); // 客户端
62     // 这样的编码对客户暴露了Department的工作原理，于是客户知道:Department用以追踪"经理"这条信息。
63 
64     return a.exec();
65 }

【2】隐藏委托关系

 1 class Person
 2 {
 3 public:
 4     // 如果对客户隐藏Department，可以减少耦合。为了到达预期的目的，在Person中建立一个简单的委托函数。
 5     Person getManager()
 6     {
 7         return m_department->get_manager(); // 隐藏委托类
 8     }
 9 
10     QString getName()
11     {
12         return m_name;
13     }
14     void setName(QString name)
15     {
16         m_name = name;
17     }
18 
19     Department* get_department()
20     {
21         return m_department; // 获取部门对象
22     }
23 
24     void set_department(Department *department)
25     {
26         m_department = department;
27     }
28 
29 private:
30     QString m_name;
31     Department *m_department;
32 };
33 
34 class Department
35 {
36 public:
37     QString getCode()
38     {
39         return m_code;
40     }
41     void setCode(QString code)
42     {
43         m_code = code;
44     }
45     Person get_manager()
46     {
47         return m_manager; // 获取经理人
48     }
49     void set_manager(Person manager)
50     {
51         m_manager = manager;
52     }
53 
54 private:
55     QString m_code;
56     Person m_manager;
57 };
58 
59 int main(int argc, char *argv[])
60 {
61     QCoreApplication a(argc, argv);
62 
63     Person person;
64     QString strName = person.getManager().getName(); // 客户端调用方式
65 
66     return a.exec();
67 }

【3】总结

客户通过一个委托类来调用另一个对象。

在服务类上建立客户所需的所有函数，用以隐藏委托关系。

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