策略模式

IStrategy.java

public interface IStrategy {

	public void operate();
	
}

BackDoor.java

/**
 * 乔国老开后门
 */
public class BackDoor implements IStrategy {

	@Override
	public void operate() {
		System.out.println("找乔国老帮忙，让吴国太给孙权施加压力");
	}

}

GivenGreenLight.java

/**
 * 吴国太开绿灯
 */
public class GivenGreenLight implements IStrategy {

	@Override
	public void operate() {
		System.out.println("求吴国太开绿灯，放行！");
	}

}

BlockEnemy.java

/**
 * 孙夫人断后
 */
public class BlockEnemy implements IStrategy {

	@Override
	public void operate() {
		System.out.println("孙夫人断后，挡住追兵");
	}

}

Context.java

/**
 * 锦囊
 */
public class Context {

	
	private IStrategy strategy;
	
	public Context(IStrategy strategy) {
		this.strategy = strategy;
	}
	
	public void operate() {
		this.strategy.operate();
	}
	
}

ZhaoYun.java

public class ZhaoYun {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		Context context;
		//刚刚到吴国的时候拆一个
		System.out.println("---刚刚到吴国的时候拆第一个---");
		context = new Context(new BackDoor()); //拿到妙计
		context.operate(); //拆开执行
		System.out.println("\n\n\n\n\n\n");
		
		System.out.println("---刘备乐不思蜀了，拆第二个了---");
		context = new Context(new GivenGreenLight()); //拿到妙计
		context.operate(); //执行了第二个锦囊
		System.out.println("\n\n\n\n\n\n");
		
		System.out.println("---孙权的小兵追来了，咋办？拆第三个---");
		context = new Context(new BlockEnemy());
		context.operate();
		System.out.println("\n\n\n\n\n");
		
	}

}