感觉就是策略模式强化版,但是绝非简单的通过状态来管理行为之间的逻辑关系,而是把行为当作状态,简单的说在什么状态下决定执行什么行为是有效的,同时改变下一行为(状态),还有一点是所有代码中没有IF,让当前行为决定做那些事情是有效的.
书上是这么说的:允许对象在内部状态改变是改变他的行为,对象看起来好像是修改了它的类.
以下以冰箱里面有一头鹿怎样把大象放进冰箱的状态关系为例说明:
- 打开冰箱
- 把鹿拿出冰箱
- 把大象塞进去
- 把冰箱门关上
Code
#region 接口
/// <summary>
/// 动物接口
/// </summary>
public interface IAnimal
{
String Name { get; }
}
/// <summary>
/// 行为接口
/// </summary>
public interface IAction
{
void AddAnimal(IAnimal animal);
void RemoveAnimal(IAnimal animal);
void OpenIceBox();
void ClosedIceBox();
}
/// <summary>
/// 冰箱状态
/// </summary>
public interface IIceBox
{
IAction Status { get; set; }
IAnimal Animal { get; set; }
IAction OpenIcebox { get; set; }
IAction InsertAnimal { get; set; }
IAction DeleteAnimal { get; set; }
IAction CloseIcebox { get; set; }
}
#endregion
#region Status
/// <summary>
/// 打开冰箱
/// </summary>
public class OpenIcebox : IAction
{
IIceBox icebox;
public OpenIcebox(IIceBox icebox)
{
this.icebox = icebox;
}
#region IAction Members
public void AddAnimal(IAnimal animal)
{
Console.WriteLine("请先打开冰箱!");
}
public void RemoveAnimal(IAnimal animal)
{
Console.WriteLine("请先打开冰箱!");
}
public void OpenIceBox()
{
Console.WriteLine("我打开了冰箱!");
icebox.Status = icebox.DeleteAnimal;
}
public void ClosedIceBox()
{
Console.WriteLine("冰箱还没打开呢!");
}
#endregion
}
/// <summary>
/// 放入动物
/// </summary>
public class InsertAnimal : IAction
{
IIceBox icebox;
public InsertAnimal(IIceBox icebox)
{
this.icebox = icebox;
}
#region IAction Members
public void AddAnimal(IAnimal animal)
{
Console.WriteLine(string.Format("把{0}塞入了冰箱!", animal.Name));
icebox.Animal = animal;
icebox.Status = icebox.CloseIcebox;
}
public void RemoveAnimal(IAnimal animal)
{
Console.WriteLine("冰箱里面没动物啊!");
}
public void OpenIceBox()
{
Console.WriteLine("冰箱已经打开了,不能重复打开!");
}
public void ClosedIceBox()
{
Console.WriteLine("还没放动物呢!!");
}
#endregion
}
/// <summary>
/// 拿出动物
/// </summary>
public class DeleteAnimal : IAction
{
IIceBox icebox;
public DeleteAnimal(IIceBox icebox)
{
this.icebox = icebox;
}
#region IAction Members
public void AddAnimal(IAnimal animal)
{
Console.WriteLine("冰箱里面有动物了啊!!");
}
public void RemoveAnimal(IAnimal animal)
{
Console.WriteLine(string.Format("移除动物{0}", animal.Name));
icebox.Animal = null;
icebox.Status = icebox.InsertAnimal;
}
public void OpenIceBox()
{
Console.WriteLine("冰箱已经打开了,不能重复打开!");
}
public void ClosedIceBox()
{
Console.WriteLine("还没有移除动物呢");
}
#endregion
}
/// <summary>
/// 关闭冰箱
/// </summary>
public class CloseIcebox : IAction
{
IIceBox icebox;
public CloseIcebox(IIceBox icebox)
{
this.icebox = icebox;
}
#region IAction Members
public void AddAnimal(IAnimal animal)
{
Console.WriteLine("冰箱已经塞了动物了!!");
}
public void RemoveAnimal(IAnimal animal)
{
Console.WriteLine("现在应该关门了");
}
public void OpenIceBox()
{
Console.WriteLine("门是开着的,不能重复打开");
}
public void ClosedIceBox()
{
Console.WriteLine("关上了冰箱门");
icebox.Status = icebox.OpenIcebox;
}
#endregion
}
#endregion
#region 实体
public class Elephant : IAnimal
{
#region IAnimal Members
public string Name
{
get { return "大象"; }
}
#endregion
}
public class Deer : IAnimal
{
#region IAnimal Members
public string Name
{
get { return "中国麋鹿"; }
}
#endregion
}
public class IceBox : IIceBox
{
IAction openIcebox;
public IAction OpenIcebox
{
get { return openIcebox; }
set { openIcebox = value; }
}
IAction insertAnimal;
public IAction InsertAnimal
{
get { return insertAnimal; }
set { insertAnimal = value; }
}
IAction deleteAnimal;
public IAction DeleteAnimal
{
get { return deleteAnimal; }
set { deleteAnimal = value; }
}
IAction closeIcebox;
public IAction CloseIcebox
{
get { return closeIcebox; }
set { closeIcebox = value; }
}
IAction status;
IceBox icebox;
IAnimal animal;
public IceBox()
{
openIcebox = new OpenIcebox(this);
insertAnimal = new InsertAnimal(this);
deleteAnimal = new DeleteAnimal(this);
closeIcebox = new CloseIcebox(this);
status = openIcebox;
animal = new Deer();
}
#region IIceBox Members
public IceBox Status
{
get { return icebox; }
set { icebox = value; }
}
public IAnimal Animal
{
get { return animal; }
set { animal = value; }
}
IAction IIceBox.Status
{
get
{ return status; }
set
{ status = value; }
}
#endregion
public void Open()
{
status.OpenIceBox();
}
public void Remove(IAnimal animal)
{
status.RemoveAnimal(animal);
}
public void Add(IAnimal animal)
{
status.AddAnimal(animal);
}
public void Close()
{
status.ClosedIceBox();
}
}
#endregion
class Program
{
static void Main(string[] args)
{
Elephant e_1 = new Elephant();
Deer d_1 = new Deer();
IceBox icebox = new IceBox();
icebox.Open();
Console.WriteLine("----------尝试错误第二次的打开门-----------");
icebox.Open();
icebox.Remove(d_1);
Console.WriteLine("----------尝试错误再移除大象-----------");
icebox.Remove(d_1);
icebox.Add(e_1);
Console.WriteLine("----------尝试错误再添加一头大象-----------");
icebox.Add(e_1);
icebox.Close();
Console.WriteLine("----------再关一次门-----------");
icebox.Close();
Console.WriteLine("----------关门放大象试试-----------");
icebox.Add(e_1);
Console.Read();
}
}
