Hey there! Let's break down how to get your Python module imports working smoothly with Jython in your Java code. I notice you're already modifying PySystemState, but let's refine that approach and cover critical details you might be missing.

First, a Critical Compatibility Note #

Jython's latest stable release (as of 2024) is 2.7.x, which only supports Python 2.7-compatible modules. The CPython 3.6 paths you're adding (C:/Program Files/Python/Python36/...) won't work for most modules—Jython can't run Python 3.x-specific code or modules that rely on CPython's C extensions. Stick to Python 2.7-compatible modules or pure-Python libraries for best results.

Step-by-Step Path Configuration #

1. Correctly Set sys.path in Your Java Code #

Instead of pointing to CPython's installation directory, focus on directories containing your custom Python modules or Jython-compatible third-party libraries. Here's a cleaned-up version of your code:

import org.python.util.PythonInterpreter;
import org.python.core.*;

public class Master {
    public static void main(String[] args) {
        PythonInterpreter interpreter = new PythonInterpreter();
        PySystemState sys = Py.getSystemState();
        
        // Add directories containing your Python modules
        // Replace these paths with your actual module locations
        sys.path.append(new PyString("C:/your-custom-python-modules"));
        sys.path.append(new PyString("C:/jython-installation/Lib/site-packages")); // Jython's own site-packages
        
        // Test an import to verify
        interpreter.exec("try:\n    import your_module\n    print('Import successful!')\nexcept ImportError as e:\n    print('Import failed:', e)");
    }
}

2. Use Jython's pip for Third-Party Modules #

Never use CPython's pip to install modules for Jython—this will lead to compatibility issues. Instead, use Jython's built-in package manager:

1. Open a command prompt
2. Run jython -m pip install <module-name> (e.g., jython -m pip install requests==2.27.1—pick a Python 2.7-compatible version)
3. Installed modules will automatically be added to Jython's site-packages directory, which is already in sys.path—no need to manually append it.

3. Environment Variable Alternative #

If you don't want to hardcode paths in Java, set the PYTHONPATH system environment variable:

• On Windows: Add a new system variable named PYTHONPATH with values like C:/your-custom-python-modules;C:/jython-installation/Lib/site-packages
• Jython will automatically load all paths from PYTHONPATH on startup, so you can skip modifying sys.path in code.

Troubleshooting Tips #

• Verify your path list: Add interpreter.exec("import sys; print(sys.path)") to your code to confirm your target directories are included.
• Check for C extensions: Modules like numpy or pandas that rely on CPython's C code won't work in Jython—look for pure-Python alternatives.
• Case sensitivity: Windows file paths are case-insensitive, but Python module names are not. Ensure your import statement matches the module's filename exactly (e.g., import MyModule requires MyModule.py).

内容的提问来源于stack exchange，提问作者neverwinter