我有一个Docker容器，用vs代码运行，用pyspark连接到本地机器上的postgres数据库：

from pyspark.sql import SparkSession
spark = SparkSession \
    .builder \
    .appName("Python Spark SQL basic example") \
    .config("spark.jars", "/opt/spark/jars/postgresql-42.2.5.jar") \
    .getOrCreate()
    
df = spark.read \
    .format("jdbc") \
    .option("url", "jdbc:postgresql://host.docker.internal:5432/postgres") \
    .option("dbtable", "chicago_crime") \
    .option("user", "postgres") \
    .option("password", "postgres") \
    .option("driver", "org.postgresql.Driver") \
    .load()
type(df)

输出：**pyspark.sql. Dataframe . Dataframe **
工作原理的示例代码：

df.printSchema()
df.select('ogc_fid').show() #(Raises a Py4JJavaError sometimes)

不起作用的示例代码：

df.show(1) # Py4JJavaError and ConnectionRefusedError: [Errno 111] Connection refused
Output exceeds the size limit. Open the full output data in a text editor
---------------------------------------------------------------------------
Py4JJavaError                             Traceback (most recent call last)
    [... skipping hidden 1 frame]
Cell In[2], line 1
----> 1 df.show(1)
File /usr/local/lib/python3.9/site-packages/pyspark/sql/dataframe.py:606, in DataFrame.show(self, n, truncate, vertical)
    605 if isinstance(truncate, bool) and truncate:
--> 606     print(self._jdf.showString(n, 20, vertical))
    607 else:
File /usr/local/lib/python3.9/site-packages/py4j/java_gateway.py:1321, in JavaMember.__call__(self, *args)
   1320 answer = self.gateway_client.send_command(command)
-> 1321 return_value = get_return_value(
   1322     answer, self.gateway_client, self.target_id, self.name)
   1324 for temp_arg in temp_args:
File /usr/local/lib/python3.9/site-packages/pyspark/sql/utils.py:190, in capture_sql_exception.<locals>.deco(*a, **kw)
    189 try:
--> 190     return f(*a, **kw)
    191 except Py4JJavaError as e:
File /usr/local/lib/python3.9/site-packages/py4j/protocol.py:326, in get_return_value(answer, gateway_client, target_id, name)
    325 if answer[1] == REFERENCE_TYPE:
...
--> 438 self.socket.connect((self.java_address, self.java_port))
    439 self.stream = self.socket.makefile("rb")
    440 self.is_connected = True
ConnectionRefusedError: [Errno 111] Connection refused

有人知道这个Py4JJavaError是什么吗？以及如何克服它？