Packaging

For Packaging we use PyInstaller and with these simple steps we will create a simple executable containing PyJNIus that prints the path of currently used Java. These steps assume you have a supported version of Python for PyJNIus and PyInstaller available together with Java installed (necessary for running the application).

main.py

from jnius import autoclass

if __name__ == '__main__':
    print(autoclass('java.lang.System').getProperty('java.home'))

This will be our main.py file. You can now call PyInstaller to create a basic .spec file which contains basic instructions for PyInstaller with:

pyinstaller main.py

main.spec

The created .spec file might look like this:

# -*- mode: python -*-

block_cipher = None


a = Analysis(
    ['main.py'],
    pathex=['<some path to main.py folder>'],
    binaries=None,
    datas=None,
    hiddenimports=[],
    hookspath=[],
    runtime_hooks=[],
    excludes=[],
    win_no_prefer_redirects=False,
    win_private_assemblies=False,
    cipher=block_cipher
)

pyz = PYZ(
    a.pure,
    a.zipped_data,
    cipher=block_cipher
)

exe = EXE(
    pyz,
    a.scripts,
    exclude_binaries=True,
    name='main',
    debug=False,
    strip=False,
    upx=True,
    console=True
)

coll = COLLECT(
    exe,
    a.binaries,
    a.zipfiles,
    a.datas,
    strip=False,
    upx=True,
    name='main'
)

Notice the Analysis section, it contains details for what Python related files to collect e.g. the main.py file. For PyJNIus to work you need to include the jnius_config module to the hiddenimports list, otherwise you will get a ImportError: No module named jnius_config:

...

a = Analysis(
    ['main.py'],
    pathex=['<some path to main.py folder>'],
    binaries=None,
    datas=None,
    hiddenimports=['jnius_config'],
    hookspath=[],
    runtime_hooks=[],
    excludes=[],
    win_no_prefer_redirects=False,
    win_private_assemblies=False,
    cipher=block_cipher
)

...

After the .spec file is ready, in our case it’s by default called by the name of the .py file, we need to direct PyInstaller to use that file:

pyinstaller main.spec

This will create a folder with all required .dll and .pyd or .so shared libraries and other necessary files for our application and for Python itself.

Running

We have the application ready, but the “problem” is PyJNIus doesn’t detect any installed Java on your computer (yet). Therefore if you try to run the application, it’ll crash with a ImportError: DLL load failed: .... For this simple example if you can see jnius.jnius.pyd or jnius.jnius.so in the final folder with main.exe (or just main), the error indicates that the application could not find Java Virtual Machine.

The Java Virtual Machine is in simple terms said another necessary shared library your application needs to load (jvm.dll or libjvm.so).

On Windows this file might be in a folder similar to this:

C:\Program Files\Java\jdk1.7.0_79\jre\bin\server

and you need to include the folder to the system PATH environment variable with this command:

set PATH=%PATH%;C:\\Program Files\\Java\\jdk1.7.0_79\\jre\\bin\\server

After the jvm.dll or libjvm.so becomes available, you can safely try to run your application:

main.exe

and you should get an output similar to this:

C:\Program Files\Java\jdk1.7.0_79\jre