add Strategy Pattern

DesignPattern/README.md

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+Design pattern samples from [Head First Design Patterns](http://www.amazon.com/Head-First-Design-Patterns-Freeman/dp/0596007124)

DesignPattern/StartegyPattern/README.md

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+策略模式
+========
+
+**设计原则一：**找出应用中可能需要变化指出，把他们独立出来，不要和不需要变化的代码混在一起。
+
+**设计原则二：**针对接口编程，而不是针对实现编程。(利用多态)
+
+**设计原则三：**多用组合，少用继承。
+
+
+鸭子类继承Duck，飞行行为实现FlyBehavior接口，呱呱叫行为实现QuackBehavior接口。

DesignPattern/StartegyPattern/src/Duck.java

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+package StrategyPattern;
+
+public abstract class Duck {
+
+	QuackBehavior quackBehavior;
+	FlyBehavior flyBehavior;
+
+	public Duck() {
+
+	}
+
+	public abstract void display();
+
+	public void performQuack() {
+		quackBehavior.quack();
+	}
+
+	public void performmFly() {
+		flyBehavior.fly();
+	}
+
+	public void setFlyBehavior(FlyBehavior flyBehavior) {
+		this.flyBehavior = flyBehavior;
+	}
+
+	public void setQuackBehavior(QuackBehavior quackBehavior) {
+		this.quackBehavior = quackBehavior;
+	}
+
+	public void swim() {
+		System.out.println("All ducks float, even decoys!");
+	}
+
+}

DesignPattern/StartegyPattern/src/FlyBehavior.java

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+package StrategyPattern;
+
+public interface FlyBehavior {
+
+	public void fly();
+
+}

DesignPattern/StartegyPattern/src/FlyNoWay.java

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+package StrategyPattern;
+
+public class FlyNoWay implements FlyBehavior {
+
+	public void fly() {
+		System.out.println("I can't fly!!!");
+	}
+
+}

DesignPattern/StartegyPattern/src/FlyRocketPowered.java

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+package StrategyPattern;
+
+public class FlyRocketPowered implements FlyBehavior {
+
+	public void fly() {
+		System.out.println("I'm flying with a rocket!!!");
+	}
+
+}

DesignPattern/StartegyPattern/src/FlyWithWings.java

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+package StrategyPattern;
+
+public class FlyWithWings implements FlyBehavior {
+
+	public void fly() {
+		System.out.println("I'm flying!!!");
+	}
+
+}

DesignPattern/StartegyPattern/src/MallardDuck.java

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+package StrategyPattern;
+
+public class MallardDuck extends Duck {
+
+	public MallardDuck() {
+		quackBehavior = new Quack();
+		flyBehavior = new FlyWithWings();
+	}
+
+	public void display() {
+		System.out.println("I'm a real Mallard duck");
+	}
+
+}

DesignPattern/StartegyPattern/src/MiniDuckSimulator.java

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+package StrategyPattern;
+
+public class MiniDuckSimulator {
+
+	public static void main(String[] args) {
+		Duck mallard = new MallardDuck();
+		mallard.performQuack();
+		mallard.performmFly();
+
+		Duck model = new ModelDuck();
+		model.performmFly();
+		model.setFlyBehavior(new FlyRocketPowered());
+		model.performmFly();
+	}
+
+}

DesignPattern/StartegyPattern/src/ModelDuck.java

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+package StrategyPattern;
+
+public class ModelDuck extends Duck {
+
+	public ModelDuck() {
+		flyBehavior = new FlyNoWay();
+		quackBehavior = new Quack();
+	}
+
+	public void display() {
+		System.out.println("I'm a model duck!!!");
+	}
+
+}

DesignPattern/StartegyPattern/src/MuteQuack.java

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+package StrategyPattern;
+
+public class MuteQuack implements QuackBehavior {
+
+	public void quack() {
+		System.out.println("<< Silence >>");
+	}
+
+}

DesignPattern/StartegyPattern/src/Quack.java

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+package StrategyPattern;
+
+public class Quack implements QuackBehavior {
+
+	public void quack() {
+		System.out.println("Quack!!!");
+	}
+
+}

DesignPattern/StartegyPattern/src/QuackBehavior.java

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+package StrategyPattern;
+
+public interface QuackBehavior {
+
+	public void quack();
+
+}

DesignPattern/StartegyPattern/src/Squeak.java

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+package StrategyPattern;
+
+public class Squeak implements QuackBehavior {
+
+	public void quack() {
+		System.out.println("Squeak!!!");
+	}
+
+}