策略模式

public interface Wuqi {

	public String useWuqi();
}

public class Jian implements Wuqi{

	@Override
	public String useWuqi() {
		return "用剑";
	}
}

public class Quantou implements Wuqi{

	@Override
	public String useWuqi() {
		return "用拳头";
	}
}

public class Role {
	
	private Wuqi wuqi;
	
	private String roleName;

	public Role(String roleName) {
		this.roleName = roleName;
	}

	public Wuqi getWuqi() {
		return wuqi;
	}

	public void setWuqi(Wuqi wuqi) {
		this.wuqi = wuqi;
	}

	public void fight() {
		System.out.println(this.roleName + "_" + wuqi.useWuqi());
	}
}

public class AppTest {

	public static void main(String[] args) {
		Role king = new Role("国王");
		king.setWuqi(new Jian());
		king.fight();
		king.setWuqi(new Quantou());
		king.fight();
	}
}