source: pythonadapter/src/main/java/geniusweb/pythonadapter/PythonPartyAdapter.java

package geniusweb.pythonadapter;

import org.python.core.Py;
import org.python.core.PyObject;
import org.python.core.PySystemState;
import org.python.util.PythonInterpreter;

import geniusweb.actions.Action;
import geniusweb.connection.ConnectionEnd;
import geniusweb.inform.Inform;
import geniusweb.party.Capabilities;
import geniusweb.party.DefaultParty;
import geniusweb.party.Party;
import tudelft.utilities.listener.Listener;

/**
 * An adapter that allows you to put a python-based Party into a jar file and
 * use it with Genius2. This adapter supports the jython dialect. The reason
 * this adapter is needed is that you can not directly use the .py file in java,
 * we have to load a python interpreter and connect it to your file. *
 * <h2>Usage</h2>
 * 
 * <ul>
 * <li>Place an implementation of this class (PythonPartyAdapter) inside your
 * jar.
 * <li>Implement {@link #getPythonClass()} so that it returns the proper name of
 * your implementation.
 * <li>Point to this implementation as the mainclass in the META-INF file. Check
 * the RandomPyParty example on how to do this from Maven.
 * <li>Ensure your Python file(s) get in the root of the jar. Eg, put them in
 * resources/ or similar inside your maven project if you use maven.
 * <li>Add more dependencies as needed, eg to access the Bid class or for
 * deserializing.
 * <li>Make sure you use the jar-with-dependencies in the parties server, as
 * that includes jython.
 * </ul>
 * 
 * <h2>Working principle</h2>
 * 
 * The created jar file contains a full python interpreter plus some glue code.
 * The glue code runs your party inside the python interpreter and routes the
 * calls through the Geniuseb java structures.
 */
public abstract class PythonPartyAdapter implements Party, Listener<Inform> {

        private final PythonInterpreter interpreter = new PythonInterpreter();
        private final DefaultParty pyparty;

        public PythonPartyAdapter() {
                /**
                 * Normally Party does not have a constructor. However this is a special
                 * case where we need to initialize Python and connect the python class.
                 */
                interpreter.exec("import sys");
                addPath("");
                System.out.println("code is at " + getClass().getProtectionDomain()
                                .getCodeSource().getLocation().getPath());
                // point to sources. Should include all dependencies.
                // should work both in Eclipse and when using the compiled jar.
                addPath(getClass().getProtectionDomain().getCodeSource().getLocation()
                                .getPath());
                PySystemState state = new PySystemState();
                PyObject importer = state.getBuiltins()
                                .__getitem__(Py.newString("__import__"));
                PyObject module = importer.__call__(Py.newString(getPythonClass()));
                PyObject klass = module.__getattr__(getPythonClass());
                pyparty = (DefaultParty) klass.__call__()
                                .__tojava__(DefaultParty.class);
        }

        /**
         * @return the class/modulename of both your python module filename (eg,
         *         X.py) and your python class (eg class X) inside that file that
         *         implements {@link DefaultParty}. This file must be in the root of
         *         the jar file/working directory. The name is without an extension.
         */
        abstract public String getPythonClass();

        @Override
        public Capabilities getCapabilities() {
                return pyparty.getCapabilities();
        }

        @Override
        public String getDescription() {
                return pyparty.getDescription();
        }

        @Override
        public void notifyChange(Inform data) {
                pyparty.notifyChange(data);
        }

        @Override
        public void disconnect() {
                pyparty.disconnect();
        }

        @Override
        public void terminate() {
                pyparty.terminate();
        }

        @Override
        public void connect(ConnectionEnd<Inform, Action> connection) {
                pyparty.connect(connection);
        }

        private void addPath(String relpath) {
                String path = System.getProperty("user.dir") + "/" + relpath + "/";

                System.out.println("adding python path " + path);
                interpreter.exec("sys.path.insert(0, '" + path + "')");

        }

}