设计模式_状态模式_C#

public class Context
{
private State state;
public State State
{
get { return state; }
set { state = value; }
}
public Context(State state)
{
this.state = state;
}
/// <summary>
///
/// </summary>
public void Request()
{
state.Handler(this);
}
}
/// <summary>
///
/// </summary>
public abstract class State
{
public abstract void Handler(Context text);

}
public class ContextStateA:State
{
public override void Handler(Context text)
{
Console.WriteLine("当前状态是A");
text.State = new ContextStateB();
}
}
public class ContextStateB:State
{
public override void Handler(Context text)
{
Console.WriteLine("当前状态是B");
text.State = new ContextStateA();
}
}

ContextStateA a=new ContextStateA();
Context text=new Context(a);
text.Request();
text.Request();
Console.ReadKey();