private void button2_Click(object sender, EventArgs e)
{
//帽子不是由行为决定，而是由使用方决定，这有可能会出现带着泳帽去打网球的情况
Person p = new Person();
p.MyHat = new SwimmingHat();
p.Play("Swimming");
p.MyHat = new TennisHat();
p.Play("Play Tennis");
}
private void button1_Click(object sender, EventArgs e)
{
Person p = new Person();
p.Play("Swimming");
}
