1. 意圖：定義一系列的算法，把他們封裝起來，並且可以相互替換；
2. Strategy:策略;定義公共算法的抽象接口
abstract class Strategy
{
public abstract void AlgorithmInterface();
}
3. ConcreteStrategy:實現Strategy的接口
/// <summary>
/// A 'ConcreteStrategy' class
/// </summary>
class ConcreteStrategyA : Strategy
{
public override void AlgorithmInterface()
{
Console.WriteLine(
"Called ConcreteStrategyA.AlgorithmInterface()");
}
}
/// <summary>
/// A 'ConcreteStrategy' class
/// </summary>
class ConcreteStrategyB : Strategy
{
public override void AlgorithmInterface()
{
Console.WriteLine(
"Called ConcreteStrategyB.AlgorithmInterface()");
}
}
/// <summary>
/// A 'ConcreteStrategy' class
/// </summary>
class ConcreteStrategyC : Strategy
{
public override void AlgorithmInterface()
{
Console.WriteLine(
"Called ConcreteStrategyC.AlgorithmInterface()");
}
}
4. Context:維護一個ConcreteStrategy的引用
class Context
{
private Strategy _strategy;
// Constructor
public Context(Strategy strategy)
{
this._strategy = strategy;
}
public void ContextInterface()
{
_strategy.AlgorithmInterface();
}
}
4.Client
Context context;
// Three contexts following different strategies
context = new Context(new ConcreteStrategyA());
context.ContextInterface();
context = new Context(new ConcreteStrategyB());
context.ContextInterface();
context = new Context(new ConcreteStrategyC());
context.ContextInterface();