def insertDomain(self, domain, indegree=0, outdegree=0):
		'''增加一个域名'''
		cur = self.conn.cursor()
		cur.execute("INSERT INTO Domains VALUES (NULL,?,?,?)", (domain, indegree, outdegree))
		# 写入到文件中
		self.conn.commit()
def setRT(self, r, t):
        self.r = r
        self.t = t
        x = self.r * math.cos(self.t)
        y = self.r * math.sin(self.t)
        self.Tail.Eq(self.p1)
        self.Head.setPoint(self.Tail.x + x,self.Tail.y + y)