def robotsrulesetOfDomain(self, domain):
		'''检查domain是否在数据库中,
			否 --> (False, None)
			是 --> (True, 数据库中存储的robots.txt内容)
		'''
		exist = False
		cur = self.conn.cursor()
		# 是否存在
		cur.execute("SELECT 1 FROM Domains WHERE domain=?", (domain,))
		if cur.fetchone() :
			exist = True
		# 存在的话,结果是什么
		cur.execute("SELECT rules FROM Domains,Rulesets "
			"WHERE domain=? AND Domains.did=Rulesets.did"
			,(domain,) )
		ruleset = cur.fetchone()
		return (exist, ruleset)
def __init__(self, container):
		self.x = container.x+randint(1, floor(container.w/3))
		self.y = container.y+randint(1, floor(container.h/3))
		self.w = container.w-(self.x-container.x)
		self.h = container.h-(self.y-container.y)
		self.w -= randint(0,floor(self.w/3))
		self.h -= randint(0,floor(self.w/3))
		self.environment = int(min(4,10*(container.distance_from_center/MAP_WIDTH)+random()*2-1))
		roll = random()*0.9+(2*container.distance_from_center/MAP_WIDTH)*0.1
		self.biome = next(n for n,b in enumerate(self.biomes_CDF) if roll<b)