Python类中的修饰@classmethod 和@staticmethod【Flask】

来杯Sherry

发布于 2023-05-25 14:00:24

2550

发布于 2023-05-25 14:00:24

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：

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：

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：

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

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原始发表：2020-12-01，如有侵权请联系 cloudcommunity@tencent.com 删除

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