設計模式(16)---原型模式

時間 2019-12-10

標籤設計模式原型简体版

原文原文鏈接

1、定義ide

原型模式：用原型實例指定建立對象的種類，而且經過拷貝這些原型建立新的對象。函數

解釋：有一個設計很是複雜的對象，若是須要獲得多個這樣對象的時候，能夠先建立一個原型對象，而後使用原型對象clone出新的對象，從而實現減小內存消耗和類實例複用的目的。性能

2、UML類圖及基本代碼this

基本代碼：spa

abstract class Prototype
    {
        private string id;
        public string ID
        {
            get { return id; }
        }

        public Prototype(string id)
        {
            this.id = id;
        }

        public abstract Prototype Clone();
    }

    class ConcretePrototype : Prototype
    {
        public ConcretePrototype(string id)
            : base(id)
        { }

        public override Prototype Clone()
        {
            return (Prototype)this.MemberwiseClone();
        }
    }

客戶端調用：設計

ConcretePrototype cp1 = new ConcretePrototype("a");
            ConcretePrototype cp2 = (ConcretePrototype)cp1.Clone();

3、具體實例code

編寫一個簡歷，包含姓名、性別、年齡、工做經歷等，而後複製多份進行顯示。對象

實例代碼及運行結果：blog

class Program
    {
        static void Main(string[] args)
        {
            Resume resume1 = new Resume("tom");
            resume1.SetPersonInfo("man", "17");
            resume1.SetWorkExperience("1980-1990", "xx company");

            Resume resume2 = (Resume)resume1.Clone();
            resume2.SetWorkExperience("1990-2000", "yy company");

            Resume resume3 = (Resume)resume1.Clone();
            resume3.SetPersonInfo("man", "19");

            resume1.Display();
            resume2.Display();
            resume3.Display();

            Console.Read();
        }
    }

    class Resume : ICloneable
    {
        private string name;
        private string sex;
        private string age;
        private string timeArea;
        private string company;

        public Resume(string name)
        {
            this.name = name;
        }

        public void SetPersonInfo(string sex, string age)
        {
            this.sex = sex;
            this.age = age;
        }

        public void SetWorkExperience(string timeArea, string company)
        {
            this.timeArea = timeArea;
            this.company = company;
        }

        public void Display()
        {
            Console.WriteLine("{0} {1} {2}", name, sex, age);
            Console.WriteLine("workexperience:{0} {1}", timeArea, company);
        }

        public object Clone()
        {
            return (object)this.MemberwiseClone();
        }
    }

View Code

實例延伸：接口

上述實例總MemberwiseClone（）方法是：若是字段是值類型，則對該字段執行逐位複製，若是字段是引用類型，則複製引用，但不復制引用的對象。這稱之爲淺拷貝，被複制對象的全部變量都含有與原來對象相同的值，而全部的對其餘對象的引用都仍然指向原來的對象。接下來，將工做經歷單獨拿出來做爲一個類在簡歷類中引用。以下：

class Program
    {
        static void Main(string[] args)
        {
            Resume resume1 = new Resume("tom");
            resume1.SetPersonInfo("man", "17");
            resume1.SetWorkExperience("1980-1990", "xx company");

            Resume resume2 = (Resume)resume1.Clone();
            resume2.SetWorkExperience("1990-2000", "yy company");

            Resume resume3 = (Resume)resume1.Clone();
            resume1.SetWorkExperience("2000-2010", "zz company");

            resume1.Display();
            resume2.Display();
            resume3.Display();

            Console.Read();
        }
    }

    class WorkExperience
    {
        private string timeArea;
        public string TimeArea
        {
            get { return timeArea; }
            set { timeArea = value; }
        }

        private string company;
        public string Company
        {
            get { return company; }
            set { company = value; }
        }
    }

    class Resume : ICloneable
    {
        private string name;
        private string sex;
        private string age;

        private WorkExperience work;

        public Resume(string name)
        {
            this.name = name;
            work = new WorkExperience();
        }

        public void SetPersonInfo(string sex, string age)
        {
            this.sex = sex;
            this.age = age;
        }

        public void SetWorkExperience(string timeArea, string company)
        {
            work.TimeArea = timeArea;
            work.Company = company;
        }

        public void Display()
        {
            Console.WriteLine("{0} {1} {2}", name, sex, age);
            Console.WriteLine("workexperience:{0} {1}", work.TimeArea, work.Company);
        }

        public object Clone()
        {
            return (object)this.MemberwiseClone();
        }
    }

View Code

結果以下：

分析：工做經歷是有3段，但運行結果只顯示一段。因而可知淺拷貝對於類中引用對象的複製並不成功。

4、概念講解

淺拷貝：當對象的字段值被拷貝時，字段引用的對象不會被拷貝。例如，若是一個對象有一個指向字符串的字段，而且咱們對該對象作了一個淺拷貝，那麼這兩個對象將引用同一個字符串。

深拷貝：對對象實例中字段引用的對象也進行拷貝，若是一個對象有一個指向字符串的字段，而且咱們對該對象進行了深拷貝的話，那麼咱們將建立一個對象和一個新的字符串，新的對象將引用新的字符串。

也就是說，執行深拷貝建立的新對象和原來對象不會共享任何東西，改變一個對象對另一個對象沒有任何影響，而執行淺拷貝建立的新對象與原來對象共享成員，改變一個對象，另一個對象的成員也會改變。

5、實例改進

一樣是上述的實例，對於有引用字段的，本例使用深拷貝，代碼以下：

class Program
    {
        static void Main(string[] args)
        {
            Resume resume1 = new Resume("tom");
            resume1.SetPersonInfo("man", "17");
            resume1.SetWorkExperience("1980-1990", "xx company");

            Resume resume2 = (Resume)resume1.Clone();
            resume2.SetWorkExperience("1990-2000", "yy company");

            Resume resume3 = (Resume)resume1.Clone();
            resume1.SetWorkExperience("2000-2010", "zz company");

            resume1.Display();
            resume2.Display();
            resume3.Display();

            Console.Read();
        }
    }

    class WorkExperience:ICloneable //實現ICloneable接口
    {
        private string timeArea;
        public string TimeArea
        {
            get { return timeArea; }
            set { timeArea = value; }
        }

        private string company;
        public string Company
        {
            get { return company; }
            set { company = value; }
        }

        public object Clone()
        {
            return (object)this.MemberwiseClone();
        }
    }

    class Resume : ICloneable
    {
        private string name;
        private string sex;
        private string age;

        private WorkExperience work;

        public Resume(string name)
        {
            this.name = name;
            work = new WorkExperience();
        }

        private Resume(WorkExperience work)
        {
            this.work = (WorkExperience)work.Clone();//提供Clone方法調用的私有構造函數，以便克隆工做經歷的數據
        }

        public void SetPersonInfo(string sex, string age)
        {
            this.sex = sex;
            this.age = age;
        }

        public void SetWorkExperience(string timeArea, string company)
        {
            work.TimeArea = timeArea;
            work.Company = company;
        }

        public void Display()
        {
            Console.WriteLine("{0} {1} {2}", name, sex, age);
            Console.WriteLine("workexperience:{0} {1}", work.TimeArea, work.Company);
        }

        public object Clone()
        {
            Resume obj = new Resume(this.work);//調用私有構造方法，讓工做經歷克隆完成，而後在給這個簡歷對象的相關字段賦值，最終返回一個深拷貝的對象 
            obj.name = this.name;
            obj.sex = this.sex;
            obj.age = this.age;
            return obj;
        }
    }