{"id":269,"date":"2021-06-09T10:02:28","date_gmt":"2021-06-09T02:02:28","guid":{"rendered":"https:\/\/swordofmorning.com\/?p=269"},"modified":"2025-10-09T13:56:05","modified_gmt":"2025-10-09T05:56:05","slug":"design-pattern-01-design-principles-of-class","status":"publish","type":"post","link":"https:\/\/swordofmorning.com\/index.php\/2021\/06\/09\/design-pattern-01-design-principles-of-class\/","title":{"rendered":"\u8bbe\u8ba1\u6a21\u5f0f 01 \u7c7b\u7684\u8bbe\u8ba1\u539f\u5219"},"content":{"rendered":"

<\/div><\/p>\n

\u4e00\u3001\u8ba9\u7c7b\u5c3d\u53ef\u80fd\u5c0f<\/h2>\n

  \u5bf9\u5355\u4e2a\u7c7b\u6211\u4eec\u5efa\u8bae\u5176\u884c\u6570\u4e0d\u8d85\u8fc750\u884c\uff0c\u4f46\u8fd9\u662f\u4e00\u79cd\u4e0d\u4e25\u8c28\u7684\u6807\u51c6\uff0c\u6211\u4eec\u5c06\u91c7\u7528\u804c\u8d23\u7684\u9879\u6570\u6765\u5ea6\u91cf\u4e00\u4e2a\u7c7b\u7684\u5927\u5c0f\u3002\u4e0b\u9762\u5c06\u63d0\u5230\u4e00\u4e9b\u539f\u5219\u3002<\/p>\n

\u4e8c\u3001\u5355\u4e00\u804c\u8d23\u539f\u5219\uff08SRP\uff09<\/h2>\n

  \u5355\u4e00\u804c\u8d23\u539f\u5219\uff08Single Responsibility Principle\uff09\u89c4\u5b9a\uff0c\u6bcf\u4e2a\u8f6f\u4ef6\u5355\u5143\uff0c\u5176\u4e2d\u5305\u62ec\u7ec4\u4ef6\u3001\u7c7b\u548c\u822a\u6bcd\u662f\uff0c\u5e94\u8be5\u53ea\u6709\u4e00\u4e2a\u5355\u4e00\u4e14\u660e\u786e\u5b9a\u4e49\u7684\u804c\u8d23\u3002<\/p>\n

\u4e09\u3001\u5f00\u95ed\u539f\u5219\uff08OCP\uff09<\/h2>\n

  \u5f00\u95ed\u539f\u5219\uff08Open Closed Principle\uff09\u6307\u51fa\u8f6f\u4ef6\u5b9e\u4f53\uff08\u6a21\u5757\u3001\u7c7b\u3001\u51fd\u6570\u7b49\uff09\u5bf9\u6269\u5c55\u5e94\u8be5\u662f\u5f00\u653e\u7684\uff0c\u4f46\u662f\u5bf9\u4fee\u6539\u5e94\u8be5\u662f\u5c01\u95ed\u7684\u3002\u5c06\u9700\u8981\u6269\u5c55\u7684\u4ee3\u7801\u62bd\u8c61\u51fa\u6765\uff0c\u901a\u8fc7\u6269\u5c55\u6765\u589e\u52a0\u65b0\u7684\u529f\u80fd\uff0c\u800c\u4e0d\u4fee\u6539\u539f\u6709\u7684\u4ee3\u7801\u3002\u5f00\u95ed\u539f\u5219\u5177\u4f53\u7684\u5b9e\u8df5\u6709\u4e24\u79cd\u53ef\u80fd\uff0c\u5176\u4e2d\u4e00\u79cd\u662f\u5c06\u53d8\u5316\u4f9d\u8d56\u6210\u63a5\u53e3\uff1b\u53e6\u4e00\u79cd\uff0c\u5c06\u53d8\u5316\u62bd\u8c61\u6210\u65b9\u6cd5\uff0c\u5177\u4f53\u4ea4\u7ed9\u5b50\u7c7b\u3002<\/p>\n

\u56db\u3001\u91cc\u6c0f\u66ff\u6362\u539f\u5219\uff08LSP\uff09<\/h2>\n

  \u91cc\u6c0f\u66ff\u6362\u539f\u5219\uff08Liskov Substitution Principle\uff09\u7684\u7b80\u5355\u8868\u8ff0\uff1a\u5b50\u7c7b\u4e0d\u80fd\u79fb\u9664\u7236\u7c7b\u5df2\u7ecf\u5b9e\u73b0\u7684\u529f\u80fd\uff0c\u5b50\u7c7b\u5904\u7406\u7684\u95ee\u9898\u5e94\u8be5\u6bd4\u7236\u7c7b\u7684\u5e7f\uff0c\u5982\u679c\u9047\u5230\u9700\u8981\u79fb\u9664\u7236\u7c7b\u90e8\u5206\u529f\u80fd\u7684\u65f6\u5019\uff0c\u5c1d\u8bd5\u4f7f\u7528\u7ec4\u5408\u7684\u65b9\u5f0f\u5c06\u7236\u7c7b\u4f5c\u4e3a\u5b50\u7c7b\u7684\u6210\u5458\u6765\u4f7f\u7528\u3002<\/p>\n

4.1 \u5b9e\u4f8b<\/h3>\n

  \u8003\u8651\u4e0b\u9762\u4e00\u79cd\u60c5\u51b5\uff1a\u6211\u4eec\u6709\u4e00\u4e2a\u77e9\u5f62\u7c7bRect\uff0c\u73b0\u5728\u6211\u4eec\u60f3\u8981\u5b9e\u73b0\u6b63\u65b9\u5f62\u7c7bSqu\u3002<\/p>\n

class Rect\n{\nprivate:\n    int x, y;\npublic:\n    \/\/ \u6784\u9020\u51fd\u6570\n    Rect(const int& p_x = 3, const int& p_y = 5)\n    {\n        x = p_x;\n        y = p_y;\n    }\n\n    \/\/ \u8bbe\u7f6e\u9ad8\n    void setHeight(int p_y)\n    {\n        y = p_y;\n    }\n\n    \/\/ \u8bbe\u7f6e\u5bbd\n    void setWidth(int p_x)\n    {\n        x = p_x;\n    }\n\n    \/\/ \u53d6\u5f97\u9762\u79ef\n    int GetArea()\n    {\n        return x * y;\n    }\n};<\/code><\/pre>\n
4.2 \u4e0d\u597d\u7684\u5b9e\u73b0<\/h2>\n
  \u5982\u679c\u6211\u4eec\u8981\u4f7f\u7528\u7ee7\u627f\u7684\u65b9\u5f0f\u6765\u5b9e\u73b0Squ\uff0c\u5c06\u662f\u5982\u4e0b\u65b9\u5f0f\uff08\u4f46\u7ee7\u627f\u662f\u4e0d\u597d\u7684\u65b9\u5f0f<\/strong>\uff09\u3002\u8fd9\u91cc\u6211\u4eec\u9700\u8981\u4f7f\u7528virtual\u5c06setWidth()\u548csetHeight()\u58f0\u660e\u4e3a\u865a\u51fd\u6570\uff0c\u4e4b\u540e\u5728Squ\u4e2d\u8986\u5199\u57fa\u51fd\u6570\uff1a<\/p>\n
class Squ :public Rect\n{\npublic:\n    Squ(const int& p_e = 3) :Rect{ p_e, p_e } {};\n\n    virtual void setHeight(int p_e) override\n    {\n        Rect::setHeight(p_e);\n        Rect::setWidth(p_e);\n    }\n\n    virtual void setWidth(int p_e) override\n    {\n        Rect::setHeight(p_e);\n        Rect::setWidth(p_e);\n    }\n\n    void setEdge(int p_e)\n    {\n        Rect::setHeight(p_e);\n        Rect::setWidth(p_e);\n    }\n};<\/code><\/pre>\n
  \u8fd9\u91cc\u4f7f\u7528\u865a\u51fd\u6570\u662f\u4e0d\u597d\u7684\uff0c\u5b83\u8bd5\u56fe\u201c\u79fb\u9664\u201d\u57fa\u7c7b\u7684\u65b9\u6cd5\u3002\u800c\u4f7f\u7528\u5e38\u89c4\u7684\u7ee7\u627f\uff08\u4e0d\u9002\u7528virtual\uff09\uff0c\u5219\u57fa\u7c7b\u7684\u65b9\u6cd5\u4e5f\u88ab\u7ee7\u627f\u5230\u5b50\u7c7b\u4e2d\uff0c\u867d\u7136\u8fd9\u4e9b\u65b9\u6cd5\u4e0d\u4f1a\u88ab\u4f7f\u7528\u3002<\/p>\n
4.3 \u597d\u7684\u5b9e\u73b0<\/h3>\n
class Squ\n{\nprivate:\n    Rect impl;\npublic:\n    Squ(const int& p_e = 3)\n    {\n        impl = Rect(p_e, p_e);\n    }\n\n    void setEdge(int p_e)\n    {\n        impl.setHeight(p_e);\n        impl.setWidth(p_e);\n    }\n\n    int GetArea()\n    {\n        return impl.GetArea();\n    }\n};<\/code><\/pre>\n
  \u8fd9\u91cc\u5c06\u7236\u7c7b\u4f5c\u4e3a\u5b50\u7c7b\u7684\u6210\u5458\u6765\u4f7f\u7528\uff0c\u907f\u514d\u4e86\u7ee7\u627f\u5e26\u6765\u7684\u4e00\u7cfb\u5217\u95ee\u9898\u3002\u8fd9\u4fbf\u662f\u91cc\u6c0f\u66ff\u6362\u539f\u5219\u7684\u7b80\u5355\u5b9e\u4f8b\u3002<\/p>\n
\u4e94\u3001\u63a5\u53e3\u9694\u79bb\u539f\u5219\uff08ISP\uff09<\/h2>\n
  \u63a5\u53e3\u9694\u79bb\u539f\u5219\uff08Interface Segregation Principe\uff09\u6307\u51fa\u63a5\u53e3\u4e0d\u5e94\u8be5\u5305\u542b\u90a3\u4e9b\u4e0e\u5b9e\u73b0\u7c7b\u65e0\u5173\u7684\u6210\u5458\u51fd\u6570\uff0c\u6216\u8005\u8fd9\u4e9b\u7c7b\u4e0d\u80fd\u4ee5\u6709\u610f\u4e49\u7684\u65b9\u5f0f\u5b9e\u73b0\u3002\u6211\u4eec\u5e94\u8be5\u5c06\u5bbd\u63a5\u53e3\u5206\u89e3\u6210\u66f4\u5c0f\u4e14\u9ad8\u5185\u805a\u7684\u63a5\u53e3\u3002\u751f\u6210\u7684\u5c0f\u63a5\u53e3\u4e5f\u79f0\u4e3a\u89d2\u8272\u63a5\u53e3\u3002<\/p>\n
5.1 \u5b9e\u4f8b<\/h3>\n
  \u8003\u8651\u4e0b\u9762\u4e00\u4e2a\u4f8b\u5b50\uff0c\u6211\u4eec\u6709\u4e00\u4e2aBird\u7c7b\u3001\u6211\u4eec\u60f3\u5b9e\u73b0Sparrow\u7c7b\u548cPenguin\u7c7b\u3002<\/p>\n
class Bird\n{\npublic:\n    virtual void eat();\n\n    virtual void run();\n\n    virtual void fly();\n};\n\nclass Sparrow :public Bird\n{\npublic:\n    virtual void eat() override;\n\n    virtual void run() override;\n\n    virtual void fly() override;\n};\n\nclass Punguin :public Bird\n{\npublic:\n    virtual void eat() override;\n\n    virtual void run() override;\n\n    virtual void fly() override;\n    \/\/ ?\n};<\/code><\/pre>\n
  \u5bf9\u4e8e\u4e0a\u8ff0\u60c5\u51b5\uff0c\u4f01\u9e45\u662f\u4e0d\u4f1a\u98de\u7684\uff0c\u4e3a\u4e86\u5e94\u5bf9\u8fd9\u79cd\u60c5\u51b5\uff0c\u6211\u4eec\u9700\u8981\u62c6\u5206\u4ed6\u4eec\u7684\u63a5\u53e3\uff1a<\/p>\n
5.2 \u62c6\u5206\u63a5\u53e3\u540e<\/h2>\n
class Lifeform\n{\npublic:\n    virtual void eat() = 0;\n    virtual void run() = 0;\n};\n\nclass Flyable\n{\npublic:\n    virtual void fly() = 0;\n};\n\nclass Sparrow : public Lifeform, public Flyable\n{\n    \/\/ do sth\n};\n\nclass Penguin : public Lifeform\n{\n    \/\/ do sth\n};<\/code><\/pre>\n
\u516d\u3001\u65e0\u5faa\u73af\u4f9d\u8d56\u539f\u5219<\/h2>\n
  \u8003\u8651\u4e0b\u9762\u4e00\u4e2a\u60c5\u51b5\uff0c\u6211\u4eec\u9700\u8981\u5b9e\u73b0\u4e00\u4e2a\u8d2d\u7269\u7cfb\u7edf\uff0c\u6709Customer\u548cAccount\u4e24\u4e2a\u7c7b\uff1a<\/p>\n
6.1 \u5b9e\u4f8b<\/h3>\n
\/\/ Customer.h\nclass Customer\n{\nprivate:\n    Account customerAccount;\n};\n\n\/\/ Account.h\nclass Account\n{\nprivate:\n    Customer owner;\n};<\/code><\/pre>\n
  \u8fd9\u6837\u662f\u65e0\u6cd5\u901a\u8fc7\u7f16\u8bd1\u7684\uff0c\u4f46\u662f\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u524d\u7f6e\u58f0\u660e\u7684\u65b9\u5f0f\u4f7f\u5b83\u901a\u8fc7\u7f16\u8bd1\u3002\u8fd9\u91cc\u524d\u7f6e\u7684\u662f\u6807\u8bc6\u7b26\u7684\u58f0\u660e\uff0c\u4f46\u662f\u4e0d\u5b9a\u4e49\u8be5\u6807\u8bc6\u7b26\u7684\u5b8c\u6574\u7ed3\u6784\uff0c\u8fd9\u4e9b\u7c7b\u578b\u6709\u65f6\u5019\u53c8\u88ab\u79f0\u4e3a\u4e0d\u5b8c\u6574\u7c7b\u578b\u3002\u56e0\u6b64\uff0c\u53ea\u80fd\u58f0\u660e\u5b83\u4eec\u7684\u6307\u9488\u6216\u5f15\u7528\uff0c\u800c\u4e0d\u80fd\u7528\u4e8e\u5b9e\u4f8b\u5316\u7684\u6210\u5458\u53d8\u91cf\uff0c\u56e0\u4e3a\u7f16\u8bd1\u5668\u5bf9\u5176\u5927\u5c0f\u4e00\u65e0\u6240\u77e5\u3002<\/p>\n
6.2 \u4f7f\u7528\u524d\u7f6e\u58f0\u660e<\/h3>\n
\/\/ Account.h\n#pragma once\n\nclass Customer;\n\nclass Account\n{\nprivate:\n    Customer* owner;\npublic:\n    Account() { \/* do nothing *\/ }\n\n    void setOwner(Customer* p_owner)\n    {\n        owner = p_owner;\n    }\n};\n\n\/\/ Customer.h\n#pragma once\n\nclass Account;\n\nclass Customer\n{\nprivate:\n    Account* customerAccount;\npublic:\n    Customer() { \/* do nothing *\/ }\n\n    void setAccount(Account* p_Account)\n    {\n        customerAccount = p_Account;\n    }\n};\n\n\/\/ main.cpp\n#include <iostream>\n#include "Account.h"\n#include "Customer.h"\n\nint main()\n{\n    Account* acc = new Account{ };\n    Customer* cus = new Customer{ };\n    acc->setOwner(cus);\n    cus->setAccount(acc);\n\n    return 0;\n}<\/code><\/pre>\n
  \u8fd9\u6837\u867d\u7136\u89e3\u51b3\u4e86\u7f16\u8bd1\u7684\u95ee\u9898\uff0c\u4f46\u662f\u5bfc\u5165\u4e86\u5faa\u73af\u4f9d\u8d56\uff0c\u5f53Account\u5b9e\u4f8b\u88ab\u5220\u9664\u7684\u65f6\u5019\uff0cCustomer\u4e2d\u7684Account\u4ecd\u7136\u5b58\u5728\uff0c\u5e76\u4e14\u6307\u5411\u88ab\u5220\u9664\u7684Account\u3002\u8fd9\u5c06\u5bfc\u81f4\u4e0d\u786e\u5b9a\u72b6\u6001\u3002\u4e0b\u9762\u6211\u4eec\u5c06\u4ecb\u7ecd\u6253\u7834\u5faa\u73af\u4f9d\u8d56\u7684\u65b9\u6cd5\u3002<\/p>\n
\u4e03\u3001\u4f9d\u8d56\u8f6c\u7f6e\u539f\u5219\uff08DIP\uff09<\/h2>\n
7.1 Cus-Acc\u6848\u4f8b\u7684\u4f9d\u8d56\u8f6c\u7f6e<\/h3>\n
  \u4e0b\u9762\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u4e00\u4e2a\u63a5\u53e3\u7c7b\u6765\u6253\u7834\u7c7b\u4e0a\u7684\u5faa\u73af\u4f9d\u8d56\uff1a
\n
\"\u56fe1\"
\u56fe1\uff1a\u4f7f\u7528\u63a5\u53e3\u7c7b<\/figcaption><\/figure>
\n