Java InputStream转Python（PY4J）

Question

I'm running Java code in python using PY4J ( http://py4j.sourceforge.net/ ).

My java function returns an InputStream and I would like to manipulate it in my python code:

Java code:

public InputStream getPCAP(key) {
        InputStream inputStream = cyberStore.getPCAP(pcapStringKey);
        return inputStream;
}

Python code:

from py4j.java_gateway import JavaGateway

gateway = JavaGateway()
input_stream = PY4J_GateWay.getPCAP(key); 
...

How can I get the InputStream in python?

Should I convert it to something else in the java code before returning it to python?

Answer 1

I'm guessing you want to read from the input stream.

Java's API lets you read from an InputStream into a byte array. There is no simple way to pass a Pythonic bytearray by reference, yet you can easily add a method which reads from an InputStream and returns a byte array:

public byte[] read(InputStream stream, int count) throws IOException {
    byte[] bytes = new byte[count];
    stream.read(bytes);
    return bytes;
}

Then, in Python you can call this method to read from the InputStream :

gateway = JavaGateway()
input_stream = gateway.getPCAP(key)
data = gateway.read(input_stream, 1000) # reads 1000 bytes from input_stream