Using a java library from python

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You could also use Py4J. There is an example on the frontpage and lots of documentation, but essentially, you just call Java methods from your python code as if they were python methods:

>>> from py4j.java_gateway import JavaGateway
>>> gateway = JavaGateway() # connect to the JVM
>>> java_object = gateway.jvm.mypackage.MyClass() # invoke constructor
>>> other_object = java_object.doThat()
>>> other_object.doThis(1,'abc')
>>> gateway.jvm.java.lang.System.out.println('Hello World!') # call a static method

As opposed to Jython, Py4J runs in the Python VM so it is always "up to date" with the latest version of Python and you can use libraries that do not run well on Jython (e.g., lxml). The communication is done through sockets instead of JNI.

Disclaimer: I am the author of Py4J

Take a look at Jython. It's kind of like JNI, but replace C with Python, i.e. you can call Python from Java and vice versa. It's not totally clear what you're trying to do or why your current approach isn't what you want.

Wrap your Java-Code in a Container (Servlet / EJB).

So you don ́t loose time in the vm-startup and you go the way to more service-oriented.

For the wraping you can use jython (only make sense if you are familiar with python)

Choose a communication-protocoll in which python and java can use:

• json (see www.json.org)
• rmi (Python: JPype)
• REST
• SOAP (only for the brave)

Choose something you or your partners are familliar with!

If you really want to embed your Java app within your Python process, have a look at JPype. It provides access to Java through JNI.

How about using swig: http://www.swig.org/Doc1.3/Java.html ?

Give JCC a try http://pypi.python.org/pypi/JCC/2.1

JCC is a code generator for calling Java directly from CPython. It supports CPython 2.3+, several JREs (Sun JDK 1.4+, Apple JRE 1.4+, and OpenJDK 1.7) on OS X, Linux, Solaris, and Windows. It's produced by the Open Source Application Foundation (OSAF, the people making Chandler) and is released under an Apache-style license.

From the package description:

JCC is a C++ code generator for producing the glue code necessary to call into Java classes from CPython via Java's Native Invocation Interface (JNI).

JCC generates C++ wrapper classes that hide all the gory details of JNI access as well Java memory and object reference management.

JCC generates CPython types that make these C++ classes accessible from a Python interpreter. JCC attempts to make these Python types pythonic by detecting iterators and property accessors. Iterators and mappings may also be declared to JCC.

You can use a library called BridgeService that exposes (for now) Java code as Rest API.

https://github.com/adobe/bridgeService

You can either put your library in the project itself or if it is a project of your, you can add the bridgeService to your project and make it accessible.

For example if you want to send a call to the java class (This example will work if you launch the project as it is following Running a DEMO ):

If you send the following payload with the POST call http://localhost:8080/call:

{
 "callContent": {
 "call1": {
 "class": "com.adobe.campaign.tests.bridge.testdata.one.SimpleStaticMethods",
 "method": "methodAcceptingStringArgument",
 "args": [
 "A Real"
 ]
 }
 }
}

In the example abobe the code will execute the method methodAcceptingStringArgumentin the class com.adobe.campaign.tests.bridge.testdata.one.SimpleStaticMethods.

The return value will be :

{
 "returnValues": {
 "call1": "A Real_Success"
 },
 "callDurations": {
 "call1": 7
 }
}

• java
• python
• jython