如果我不能使用SparkContext，如何创建DataFrame？

from pyspark.sql import SparkSession

spark = SparkSession.builder \
    .appName("DataFrame Creation") \
    .getOrCreate()

df = spark.read.csv("path/to/file.csv", header=True, inferSchema=True)

df = spark.read.json("path/to/file.json")

df = spark.read.format("jdbc") \
    .option("url", "jdbc:mysql://localhost:3306/db_name") \
    .option("dbtable", "table_name") \
    .option("user", "username") \
    .option("password", "password") \
    .load()

rdd = spark.sparkContext.parallelize([(1, "Alice"), (2, "Bob"), (3, "Charlie")])
df = spark.createDataFrame(rdd, ["id", "name"])