Py4J：JVM中不存在Java

Question

我正在学习使用Py4J在python中使用Java对象。我开始尝试下面提到的一个简单示例

from py4j.java_gateway import JavaGateway
gateway = JavaGateway() 
gateway.gateway_parameters.port = 4040
gateway.jvm.java.lang.System.out.println('Hello World!')

这导致了以下错误

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/ultrausr/Downloads/spark/python/lib/py4j-0.10.7-src.zip/py4j/java_gateway.py", line 1659, in __getattr__
py4j.protocol.Py4JError: java does not exist in the JVM

如何在JVM中加载java或任何其他Java包？