CSharp: Strategy Pattern in donet core 3

 

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/// <summary>   /// 车辆行为模型   /// Abstract Behavior   /// 策略模式 Strategy Pattern   /// geovindu, Geovin Du edit   ///   /// </summary>   public abstract class VehicleBehavior   {         /// <summary>       /// 关于我       /// </summary>       /// <param name="vehicle">输入车名称</param>       public abstract void AboutMe(string vehicle);   }   /// <summary>   /// Floating capability   /// 移动的能力   /// </summary>   class FloatBehavior : VehicleBehavior   {         /// <summary>       /// 关于我       /// </summary>       /// <param name="vehicle">输入车名称</param>       public override void AboutMe(string vehicle)       {           Console.WriteLine($"我的 {vehicle} 现在能移动.");       }   }   /// <summary>   /// Flying capability   /// 飞行能力   /// </summary>   class FlyBehavior : VehicleBehavior   {       /// <summary>       /// 关于我       /// </summary>       /// <param name="vehicle">输入车名称</param>       public override void AboutMe(string vehicle)       {           Console.WriteLine($"我的 {vehicle} 现在能飞.");       }   }   /// <summary>   /// Initial behavior.Cannot do anything special.   /// </summary>   class InitialBehavior : VehicleBehavior   {       /// <summary>       /// 关于我       /// </summary>       /// <param name="vehicle">输入车名称</param>       public override void AboutMe(string vehicle)       {           Console.WriteLine($"我的 {vehicle} 刚产生.它不能做特别的事情.");       }   }   /// <summary>   /// Context class-Vehicle   /// 车对象类   /// </summary>   public class Vehicle   {       /// <summary>       ///       /// </summary>       VehicleBehavior behavior;       /// <summary>       /// 类型       /// </summary>       string vehicleType;         /// <summary>       /// 构造对象       /// </summary>       /// <param name="vehicleType">输入类型</param>       public Vehicle(string vehicleType)       {           this.vehicleType = vehicleType;           //Setting the initial behavior           this.behavior = new InitialBehavior();       }       /*        * It's your choice. You may prefer to use a setter        * method instead of using a constructor.        * You can call this method whenever we want        * to change the "vehicle behavior" on the fly.        */       /// <summary>       /// 设置       /// </summary>       /// <param name="behavior"></param>       public void SetVehicleBehavior(VehicleBehavior behavior)       {           this.behavior = behavior;       }       /*        This method will help us to delegate the behavior to        the object referenced by vehicle.You do not know about        the object type, but you simply know that this object can        tell something about it, i.e. "AboutMe()" method       */       /// <summary>       /// 显示       /// </summary>       public void DisplayAboutMe()       {           behavior.AboutMe(vehicleType);       }   }

　　

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/// <summary>  /// 策略模式 Strategy Pattern  /// geovindu, Geovin Du edit  /// </summary>  public enum OutputFormat  {      Markdown,      Html  }  /// <summary>  ///  /// </summary>  public interface IListStrategy  {        /// <summary>      ///      /// </summary>      /// <param name="sb"></param>      void Start(StringBuilder sb);      /// <summary>      ///      /// </summary>      /// <param name="sb"></param>      void End(StringBuilder sb);      /// <summary>      ///      /// </summary>      /// <param name="sb"></param>      /// <param name="item"></param>      void AddListItem(StringBuilder sb, string item);  }  /// <summary>  ///  /// </summary>  public class MarkdownListStrategy : IListStrategy  {        /// <summary>      ///      /// </summary>      /// <param name="sb"></param>      public void Start(StringBuilder sb)      {          // markdown doesn't require a list preamble      }      /// <summary>      ///      /// </summary>      /// <param name="sb"></param>      public void End(StringBuilder sb)      {        }      /// <summary>      ///      /// </summary>      /// <param name="sb"></param>      /// <param name="item"></param>      public void AddListItem(StringBuilder sb, string item)      {          sb.AppendLine($" * {item}");      }  }  /// <summary>  ///  /// </summary>  public class HtmlListStrategy : IListStrategy  {        /// <summary>      ///      /// </summary>      /// <param name="sb"></param>      public void Start(StringBuilder sb) => sb.AppendLine("<ul>");      /// <summary>      ///      /// </summary>      /// <param name="sb"></param>      public void End(StringBuilder sb) => sb.AppendLine("</ul>");      /// <summary>      ///      /// </summary>      /// <param name="sb"></param>      /// <param name="item"></param>      public void AddListItem(StringBuilder sb, string item)      {          sb.AppendLine($"  <li>{item}</li>");      }  }  /// <summary>  ///  /// </summary>  public class TextProcessor  {      /// <summary>      ///      /// </summary>      private StringBuilder sb = new StringBuilder();      /// <summary>      ///      /// </summary>      private IListStrategy listStrategy;      /// <summary>      ///      /// </summary>      /// <param name="format"></param>      /// <exception cref="ArgumentOutOfRangeException"></exception>      public void SetOutputFormat(OutputFormat format)      {          switch (format)          {              case OutputFormat.Markdown:                  listStrategy = new MarkdownListStrategy();                  break;              case OutputFormat.Html:                  listStrategy = new HtmlListStrategy();                  break;              default:                  throw new ArgumentOutOfRangeException(nameof(format), format, null);          }      }      /// <summary>      ///      /// </summary>      /// <param name="items"></param>      public void AppendList(IEnumerable<string> items)      {          listStrategy.Start(sb);          foreach (var item in items)              listStrategy.AddListItem(sb, item);          listStrategy.End(sb);      }      /// <summary>      ///      /// </summary>      /// <returns></returns>      public StringBuilder Clear()      {          return sb.Clear();      }      /// <summary>      ///      /// </summary>      /// <returns></returns>      public override string ToString() => sb.ToString();      }

　　

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/// <summary>   /// 策略模式 Strategy Pattern   /// geovindu, Geovin Du edit   /// </summary>   class Person : IEquatable<Person>, IComparable<Person>   {       /// <summary>       ///       /// </summary>       public int Id;       /// <summary>       ///       /// </summary>       public string Name;       /// <summary>       ///       /// </summary>       public int Age;       /// <summary>       ///       /// </summary>       /// <param name="other"></param>       /// <returns></returns>       public int CompareTo(Person other)       {           if (ReferenceEquals(this, other)) return 0;           if (ReferenceEquals(null, other)) return 1;           return Id.CompareTo(other.Id);       }       /// <summary>       ///       /// </summary>       /// <param name="id"></param>       /// <param name="name"></param>       /// <param name="age"></param>       public Person(int id, string name, int age)       {           Id = id;           Name = name;           Age = age;       }       /// <summary>       ///       /// </summary>       /// <param name="other"></param>       /// <returns></returns>       public bool Equals(Person other)       {           if (ReferenceEquals(null, other)) return false;           if (ReferenceEquals(this, other)) return true;           return Id == other.Id;       }       /// <summary>       ///       /// </summary>       /// <param name="obj"></param>       /// <returns></returns>       public override bool Equals(object obj)       {           if (ReferenceEquals(null, obj)) return false;           if (ReferenceEquals(this, obj)) return true;           if (obj.GetType() != this.GetType()) return false;           return Equals((Person)obj);       }       /// <summary>       ///       /// </summary>       /// <returns></returns>       public override int GetHashCode()       {           return Id;       }       /// <summary>       ///       /// </summary>       /// <returns></returns>       public override string ToString()       {           return $"序号（{nameof(Id)}）:{Id}；姓名（{nameof(Name)}）:{Name}；年岁（{nameof(Age)}）:{Age}";       }       /// <summary>       ///       /// </summary>       /// <param name="left"></param>       /// <param name="right"></param>       /// <returns></returns>       public static bool operator ==(Person left, Person right)       {           return Equals(left, right);       }       /// <summary>       ///       /// </summary>       /// <param name="left"></param>       /// <param name="right"></param>       /// <returns></returns>       public static bool operator !=(Person left, Person right)       {           return !Equals(left, right);       }       /// <summary>       ///       /// </summary>       private sealed class NameRelationalComparer : IComparer<Person>       {             /// <summary>           ///           /// </summary>           /// <param name="x"></param>           /// <param name="y"></param>           /// <returns></returns>           public int Compare(Person x, Person y)           {               if (ReferenceEquals(x, y)) return 0;               if (ReferenceEquals(null, y)) return 1;               if (ReferenceEquals(null, x)) return -1;               return string.Compare(x.Name, y.Name,                 StringComparison.Ordinal);           }       }         /// <summary>       /// 名字排序       /// </summary>       public static IComparer<Person> NameComparer { get; }         = new NameRelationalComparer();   }

　　

调用：

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//策略模式     Console.WriteLine("***策略模式 Strategy Pattern Demo.***\n");     Vehicle context = new Vehicle("Aeroplane(飞机）");     context.DisplayAboutMe();     Console.WriteLine("Setting  flying capability（设置飞行能力） to vehicle.");     context.SetVehicleBehavior(new FlyBehavior());     context.DisplayAboutMe();          Console.WriteLine("Changing the vehicle behavior（改为移动能力） again.");     context.SetVehicleBehavior(new FloatBehavior());     context.DisplayAboutMe();       //     var tp = new TextProcessor();     tp.SetOutputFormat(OutputFormat.Markdown);     tp.AppendList(new[] { "foo", "bar", "baz" });     Console.WriteLine(tp);       tp.Clear();     tp.SetOutputFormat(OutputFormat.Html);     tp.AppendList(new[] { "foo", "bar", "baz" });     Console.WriteLine(tp);       //     var people = new List<Person>();       // equality == != and comparison < = >       people.Add(new Person(1, "geovindu", 25));     people.Add(new Person(2, "涂聚文", 28));     people.Add(new Person(3, "江山", 38));     people.Add(new Person(4, "李玉", 18));     people.Add(new Person(5, "张清", 20));     people.Sort(); // meaningless by default     foreach (Person p in people)     {         Console.WriteLine("第1次ID排序:" + p.ToString());     }     Console.WriteLine("***.***\n");     // sort by name with a lambda     //名字排序     people.Sort((x, y) => x.Name.CompareTo(y.Name));       foreach (Person p in people)     {         Console.WriteLine("第2次名字排序:" + p.ToString());     }     Console.WriteLine("***.***\n");     //     people.Sort(Person.NameComparer);       foreach(Person p in people)     {         Console.WriteLine("第3次名字排序"+p.ToString());     }     Console.WriteLine("***.***\n");     people.Sort((x, y) => x.Age.CompareTo(y.Age));       foreach (Person p in people)     {         Console.WriteLine("第4次年龄排序" + p.ToString());     }         Console.ReadKey(); }

　　

输出：

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***策略模式 Strategy Pattern Demo.***   我的 Aeroplane(飞机） 刚产生.它不能做特别的事情. Setting  flying capability（设置飞行能力） to vehicle. 我的 Aeroplane(飞机） 现在能飞. Changing the vehicle behavior（改为移动能力） again. 我的 Aeroplane(飞机） 现在能移动.  * foo  * bar  * baz   <ul>   <li>foo</li>   <li>bar</li>   <li>baz</li> </ul>   第1次ID排序:序号（Id）:1；姓名（Name）:geovindu；年岁（Age）:25 第1次ID排序:序号（Id）:2；姓名（Name）:涂聚文；年岁（Age）:28 第1次ID排序:序号（Id）:3；姓名（Name）:江山；年岁（Age）:38 第1次ID排序:序号（Id）:4；姓名（Name）:李玉；年岁（Age）:18 第1次ID排序:序号（Id）:5；姓名（Name）:张清；年岁（Age）:20 ***.***   第2次名字排序:序号（Id）:1；姓名（Name）:geovindu；年岁（Age）:25 第2次名字排序:序号（Id）:3；姓名（Name）:江山；年岁（Age）:38 第2次名字排序:序号（Id）:4；姓名（Name）:李玉；年岁（Age）:18 第2次名字排序:序号（Id）:2；姓名（Name）:涂聚文；年岁（Age）:28 第2次名字排序:序号（Id）:5；姓名（Name）:张清；年岁（Age）:20 ***.***   第3次名字排序序号（Id）:1；姓名（Name）:geovindu；年岁（Age）:25 第3次名字排序序号（Id）:5；姓名（Name）:张清；年岁（Age）:20 第3次名字排序序号（Id）:4；姓名（Name）:李玉；年岁（Age）:18 第3次名字排序序号（Id）:3；姓名（Name）:江山；年岁（Age）:38 第3次名字排序序号（Id）:2；姓名（Name）:涂聚文；年岁（Age）:28 ***.***   第4次年龄排序序号（Id）:4；姓名（Name）:李玉；年岁（Age）:18 第4次年龄排序序号（Id）:5；姓名（Name）:张清；年岁（Age）:20 第4次年龄排序序号（Id）:1；姓名（Name）:geovindu；年岁（Age）:25 第4次年龄排序序号（Id）:2；姓名（Name）:涂聚文；年岁（Age）:28 第4次年龄排序序号（Id）:3；姓名（Name）:江山；年岁（Age）:38