How to access Java classes using Python

I'm glad to introduce you to a Pyjnius project. This is a Python library that can be used on the desktop or Android to access Java classes.

Source code: github.com/kivy/pyjnius

Document: pyjnius.readthedocs.org

There are also some other libraries, such as JPype or Py4j, which are not very good in design and availability. Using Jython is not another option, because we want to use python to develop Android projects.

Now let me tell you how to simply use Pyjnius:

 
 

  
  
>>> from jnius import autoclass  
  
  
>>> Stack = autoclass('java.util.Stack')  
  
  
>>> stack = Stack()  
  
  
>>> stack.push('hello')  
  
  
>>> stack.push('world')  
  
  
>>> stack.pop()  
  
  
'world' 
  
  
>>> stack.pop()  
  
  
'hello' 
 
 

In the above Code, we use the autoclass function to create a type proxy, which corresponds to all the methods and field attributes of the Java. util. Stack class in java.

OK. Maybe you want an Android-related example. Here:

 
 

  
  
from jnius import autoclass  
  
  
from time import sleep  
  
  
   
  
  
MediaRecorder = autoclass('android.media.MediaRecorder')  
  
  
AudioSource = autoclass('android.media.MediaRecorder$AudioSource')  
  
  
OutputFormat = autoclass('android.media.MediaRecorder$OutputFormat')  
  
  
AudioEncoder = autoclass('android.media.MediaRecorder$AudioEncoder')  
  
  
   
  
  
# Record the Microphone with a 3GP recorder  
  
  
mRecorder = MediaRecorder()  
  
  
mRecorder.setAudioSource(AudioSource.MIC)  
  
  
mRecorder.setOutputFormat(OutputFormat.THREE_GPP)  
  
  
mRecorder.setOutputFile('/sdcard/testrecorder.3gp')  
  
  
mRecorder.setAudioEncoder(AudioEncoder.ARM_NB)  
  
  
mRecorder.prepare()  
  
  
   
  
  
# Record 5 seconds  
  
  
mRecorder.start()  
  
  
sleep(5)  
  
  
mRecorder.stop()  
  
  
mRecorder.release() 
 
 

Now, you can get more examples from the document.

We can map Java/Python types, native arrays, and support method overloading. We use Cython + JNI internally, so the minimum consumption performance is.

At the same time, the Python for android library has been completed and can be obtained from github.

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