在flask中，经常会为了代码美观将过程封装成类，去引用这个文件， 用例子来看区别（注意看fetch_one方法的调用）
@classmethod：
代码语言：javascript复制class SQLHelper:
@staticmethod
def open():
conn = pymysql.connect(host='127.0.0.1',port=3306, user='root',passwd='123456',db='flask')
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
print('连接成功')
return cursor, conn
@staticmethod
def close(cursor,conn):
conn.commit()
cursor.close()
conn.close()
@classmethod
def fetch_one(cls, sql, args):
cursor, conn = cls.open()
cursor.execute(sql, args)
obj = cursor.fetchone()
cls.close(cursor, conn)
return obj
@classmethod
def fetch_all(cls, sql, args):
cursor, conn = cls.open()
cursor.execute(sql, args)
obj = cursor.fetchall()
cls.close(cursor, conn)
return obj
if __name__ == '__main__':
sql = "select * from users where user=%s and pwd =%s"
# s = SQLHelper()
obj = SQLHelper.fetch_one(sql, ['cold','123456'])
print(obj)@staticmethod：
代码语言：javascript复制class SQLHelper:
@staticmethod
def open():
conn = pymysql.connect(host='127.0.0.1',port=3306, user='root',passwd='123456',db='flask')
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
print('连接成功')
return cursor, conn
@staticmethod
def close(cursor,conn):
conn.commit()
cursor.close()
conn.close()
@staticmethod
def fetch_one( sql, args):
cursor, conn = SQLHelper.open()
cursor.execute(sql, args)
obj = cursor.fetchone()
SQLHelper.close(cursor, conn)
return obj
@staticmethod
def fetch_all( sql, args):
cursor, conn = SQLHelper.open()
cursor.execute(sql, args)
obj = cursor.fetchall()
SQLHelper.close(cursor, conn)
return obj
if __name__ == '__main__':
sql = "select * from users where user=%s and pwd =%s"
# s = SQLHelper()
obj = SQLHelper.fetch_one(sql, ['cold','123456'])
print(obj)可以看到，以上这两种都不用实例化
常规的：
代码语言：javascript复制class SQLHelper:
@staticmethod
def open(self):
conn = pymysql.connect(host='127.0.0.1',port=3306, user='root',passwd='123456',db='flask')
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
print('连接成功')
return cursor, conn
def close(self,cursor,conn):
conn.commit()
cursor.close()
conn.close()
def fetch_one( self,sql, args):
cursor, conn = self.open()
cursor.execute(sql, args)
obj = cursor.fetchone()
self.close(cursor, conn)
return obj
def fetch_all( self,sql, args):
cursor, conn = self.open()
cursor.execute(sql, args)
obj = cursor.fetchall()
self.close(cursor, conn)
return obj
if __name__ == '__main__':
sql = "select * from users where user=%s and pwd =%s"
s = SQLHelper()
obj = s.fetch_one(sql, ['cold','123456'])
print(obj)cls:传递的是类本身，self传递的是类的实例（即，对象），加了修饰以后，可以直接将类实例化
