语境：
Door 1using System; 2 3namespace Gof.Test.State 4{ 5 public delegate void ChangeHandler(Door door); 6 public class Door 7 { 8 public const int CLOSED = -1; 9 public const int OPENING = -2; 10 public const int OPEN = -3; 11 public const int CLOSING = -4; 12 public const int STAYOPEN = -5; 13 14 public event ChangeHandler Change; 15 private int _state = CLOSED; 16 17 public string Status() 18 { 19 switch(_state) 20 { 21 case OPENING: 22 { 23 return "Opening"; 24 } 25 case OPEN: 26 { 27 return "Open"; 28 } 29 case CLOSING: 30 { 31 return "Closing"; 32 } 33 case STAYOPEN: 34 { 35 return "StayOpen"; 36 } 37 default: 38 { 39 return "Closed"; 40 } 41 } 42 } 43 44 45 public void Touch() 46 { 47 if(_state == CLOSED) 48 { 49 SetState(OPENING); 50 } 51 else if(_state == OPENING || _state == STAYOPEN) 52 { 53 SetState(CLOSING); 54 } 55 else 56 { 57 if(_state == OPEN) 58 { 59 SetState(STAYOPEN); 60 } 61 else if(_state == CLOSING) 62 { 63 SetState(OPENING); 64 } 65 } 66 } 67 68 69 private void SetState(int state) 70 { 71 this._state = state; 72 if(Change != null) 73 { 74 Change(this); 75 } 76 } 77 78 79 public void Complete() 80 { 81 if(_state == OPENING) 82 { 83 SetState(OPEN); 84 } 85 else if(_state == CLOSING) 86 { 87 SetState(CLOSED); 88 } 89 } 90 91 92 public void TimeOut() 93 { 94 if(_state == OPEN) 95 { 96 SetState(CLOSING); 97 } 98 } 99100101 public Door()102 {103 }104 }105} 客户代码 1 Door door = new Door(); 2 door.Change +=new ChangeHandler(StateChange); 3 door.TimeOut(); 4 door.Touch(); 5 door.Touch(); 6 door.Touch(); 7 door.Touch(); 8 door.Touch(); 9 Console.ReadLine();10private static void StateChange(Gof.Test.State.Door door)11 {12 Console.WriteLine("Door state had Changed to "+door.Status());13 } 重构１，用状态模式简化Door类的状态相关代码。 Door2 1using System; 2 3namespace Gof.Test.State 4{ 5 public delegate void ChangeHandler2(Door2 door); 6 public class Door2 7 { 8 public readonly DoorState CLOSED; 9 public readonly DoorState OPENING;10 public readonly DoorState OPEN;11 public readonly DoorState CLOSING;12 public readonly DoorState STAYOPEN;1314 public event ChangeHandler2 Change;15 private DoorState _state;16 public Door2()17 {18 OPEN = new DoorOpen(this);19 CLOSING = new DoorClosing(this);20 CLOSED = new DoorClosed(this);21 OPENING = new DoorOpening(this);22 STAYOPEN = new DoorClosing(this);23 _state = CLOSED;24 }25 public string Status()26 {27 return _state.Status();28 }293031 public void Touch()32 { 33 _state.Touch(); 34 }353637 internal void SetState(DoorState state)38 {39 this._state = state;40 if(Change != null)41 {42 Change(this);43 }44 }454647 public void Complete()48 {49 _state.Touch();50 }515253 public void TimeOut()54 {55 if(_state == OPEN)56 {57 SetState(CLOSING);58 }59 } 60 }61} DoorState 1using System; 2 3namespace Gof.Test.State 4{ 5 public abstract class DoorState 6 { 7 protected Door2 _door; 8 9 public DoorState(Door2 door)10 {11 _door = door;12 }13 public abstract void Touch();14 public virtual void Complete(){}15 public virtual void TimeOut(){}1617 public string Status()18 {19 return this.GetType().Name;20 }21 }22} DoorClosed 1using System; 2 3namespace Gof.Test.State 4{ 5 public class DoorClosed : DoorState 6 { 7 public DoorClosed(Door2 door) : base(door) 8 { 9 }10 public override void Touch()11 {12 _door.SetState(_door.OPENING);13 }1415 }16} DoorClosing 1using System; 2 3namespace Gof.Test.State 4{ 5 public class DoorClosing : DoorState 6 { 7 public DoorClosing(Door2 door) : base(door) 8 { 9 }10 public override void Touch()11 {12 _door.SetState(_door.OPENING);13 }14 public override void Complete()15 {16 _door.SetState(_door.CLOSED);17 } 18 }19} DoorOpen 1using System; 2 3namespace Gof.Test.State 4{ 5 public class DoorOpen:DoorState 6 { 7 public DoorOpen(Door2 door) : base(door) 8 { 9 }10 public override void Touch()11 {12 _door.SetState(_door.STAYOPEN);13 }14 public override void TimeOut()15 {16 _door.SetState(_door.CLOSING);17 }18 }19} DoorOpening 1using System; 2 3namespace Gof.Test.State 4{ 5 public class DoorOpening : DoorState 6 { 7 public DoorOpening(Door2 door) : base(door) 8 { 9 }10 public override void Complete()11 {12 _door.SetState(_door.OPEN);13 }14 public override void Touch()15 {16 _door.SetState(_door.CLOSING);17 } 18 }19} DoorStayOpen 1using System; 2 3namespace Gof.Test.State 4{ 5 public class DoorStayOpen : DoorState 6 { 7 public DoorStayOpen(Door2 door) : base(door) 8 { 9 }10 public override void Touch()11 {12 _door.SetState(_door.CLOSING);13 } 14 }15} 重构２，把状态变成常量，每个状态只给出其下一个状态。 Door2 1using System; 2 3namespace Gof.Test.State 4{ 5 public delegate void ChangeHandler2(Door2 door); 6 public class Door2 7 { 8 public event ChangeHandler2 Change; 9 private DoorState _state;1011 public Door2()12 {13 _state = new DoorClosed();14 }1516 public string Status()17 {18 return State.Status();19 }2021 public void Touch()22 {23 State = _state.Touch(); 24 }2526 public DoorState State27 {28 get29 {30 return _state;31 }32 set 33 {34 _state = value;35 if (Change != null)36 {37 Change(this);38 }39 }40 }4142 public void Complete()43 {44 State = State.Complete();45 }4647 public void TimeOut()48 {49 State = State.TimeOut();50 } 51 }52} DoorState 1using System; 2 3namespace Gof.Test.State 4{ 5 public abstract class DoorState 6 { 7 static DoorState() 8 { 9 CLOSED = new DoorClosed();10 OPENING = new DoorOpening();11 OPEN = new DoorOpen();12 STAYOPEN = new DoorStayOpen();13 CLOSING = new DoorClosing();14 }1516 public static DoorClosed CLOSED;17 public static DoorOpening OPENING;18 public static DoorOpen OPEN;19 public static DoorStayOpen STAYOPEN;20 public static DoorClosing CLOSING;2122 public abstract DoorState Touch();2324 public virtual DoorState Complete(){return this;}2526 public virtual DoorState TimeOut(){return this;}2728 public string Status()29 {30 return this.GetType().Name;31 }32 }33} DoorClosed 1using System; 2 3namespace Gof.Test.State 4{ 5 public class DoorClosed : DoorState 6 { 7 public override DoorState Touch() 8 { 9 return DoorState.OPENING;10 }11 }12} DoorClosing 1using System; 2 3namespace Gof.Test.State 4{ 5 public class DoorClosing : DoorState 6 { 7 public override DoorState Touch() 8 { 9 return DoorState.OPENING;10 }11 public override DoorState Complete()12 {13 return DoorState.CLOSED;14 }15 }16} DoorOpen 1using System; 2 3namespace Gof.Test.State 4{ 5 public class DoorOpen:DoorState 6 { 7 public override DoorState Touch() 8 { 9 return DoorState.STAYOPEN;10 }11 public override DoorState TimeOut()12 {13 return DoorState.CLOSING;14 }15 }16} DoorStayOpen 1using System; 2 3namespace Gof.Test.State 4{ 5 public class DoorStayOpen : DoorState 6 { 7 public override DoorState Touch() 8 { 9 return DoorState.CLOSING;10 }11 }12} DoorOpening 1using System; 2 3namespace Gof.Test.State 4{ 5 public class DoorOpening : DoorState 6 { 7 public override DoorState Complete() 8 { 9 return DoorState.OPEN;10 }11 public override DoorState Touch()12 {13 return DoorState.CLOSING;14 }15 }16} 重构3，把状态变成常量，中间对象做为变量传递。 Door2 1using System; 2 3namespace Gof.Test.State 4{ 5 public delegate void ChangeHandler2(Door2 door); 6 public class Door2 7 { 8 public event ChangeHandler2 Change; 9 private DoorState _state;1011 public Door2()12 {13 _state = new DoorClosed();14 }1516 public string Status()17 {18 return _state.Status();19 }2021 public void Touch()22 {23 _state.Touch(this); 24 }2526 /**//// <summary>27 /// 这个方法其自身不调用，是在状态类里当状态变化时调用，用来激活事件。28 /// </summary>29 /// <param name="state">状态基类</param>30 public void SetState(DoorState state)31 {32 _state = state;33 if (Change != null)34 {35 Change(this);36 }37 }3839 public void Complete()40 {41 _state.Complete(this);42 }4344 public void TimeOut()45 {46 _state.TimeOut(this);47 } 48 }49} DoorState 1using System; 2 3namespace Gof.Test.State 4{ 5 public abstract class DoorState 6 { 7 static DoorState() 8 { 9 CLOSED = new DoorClosed();10 OPENING = new DoorOpening();11 OPEN = new DoorOpen();12 STAYOPEN = new DoorStayOpen();13 CLOSING = new DoorClosing();14 }1516 public static DoorClosed CLOSED;17 public static DoorOpening OPENING;18 public static DoorOpen OPEN;19 public static DoorStayOpen STAYOPEN;20 public static DoorClosing CLOSING;2122 public abstract void Touch(Door2 door);2324 public virtual void Complete(Door2 door){}2526 public virtual void TimeOut(Door2 door){}2728 public string Status()29 {30 return this.GetType().Name;31 }32 }33} DoorClosed 1using System; 2 3namespace Gof.Test.State 4{ 5 public class DoorClosed : DoorState 6 { 7 public override void Touch(Door2 door) 8 { 9 door.SetState(DoorState.OPENING);10 }11 }12}13 DoorClosing 1using System; 2 3namespace Gof.Test.State 4{ 5 public class DoorClosing : DoorState 6 { 7 public override void Touch(Door2 door) 8 { 9 door.SetState(DoorState.OPENING);10 }11 public override void Complete(Door2 door)12 {13 door.SetState(DoorState.CLOSED);14 }15 }16}17 DoorOpen 1using System; 2 3namespace Gof.Test.State 4{ 5 public class DoorOpen:DoorState 6 { 7 public override void Touch(Door2 door) 8 { 9 door.SetState(DoorState.STAYOPEN);10 }11 public override void TimeOut(Door2 door)12 {13 door.SetState(DoorState.CLOSING);14 }15 }16}17 DoorOpening 1using System; 2 3namespace Gof.Test.State 4{ 5 public class DoorOpening : DoorState 6 { 7 public override void Complete(Door2 door) 8 { 9 door.SetState(DoorState.OPEN);10 }11 public override void Touch(Door2 door)12 {13 door.SetState(DoorState.CLOSING);14 }15 }16}17 DoorStayOpen 1using System; 2 3namespace Gof.Test.State 4{ 5 public class DoorStayOpen : DoorState 6 { 7 public override void Touch(Door2 door) 8 { 9 door.SetState(DoorState.CLOSING);10 }11 }12}13转载于:https://www.cnblogs.com/nanshouyong326/archive/2007/01/10/616911.html
