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Jython is an implementation of the high-level, dynamic, object-oriented
language Python written in 100% Pure Java, and seamlessly integrated with
the Java platform. It thus allows you to run Python on any Java platform.
/*###
#
# Copyright Alan Kennedy.
#
# You may contact the copyright holder at this uri:
#
# http://www.xhaus.com/contact/modjy
#
# The licence under which this code is released is the Apache License v2.0.
#
# The terms and conditions of this license are listed in a file contained
# in the distribution that also contained this file, under the name
# LICENSE.txt.
#
# You may also read a copy of the license at the following web address.
#
# http://modjy.xhaus.com/LICENSE.txt
#
###*/
package com.xhaus.modjy;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.LineNumberReader;
import java.util.Enumeration;
import java.util.Properties;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.python.core.Options;
import org.python.core.Py;
import org.python.core.PyException;
import org.python.core.PyObject;
import org.python.core.PyString;
import org.python.core.PySystemState;
import org.python.core.PyType;
import org.python.util.PythonInterpreter;
public class ModjyJServlet extends HttpServlet {
protected final static String MODJY_PYTHON_CLASSNAME = "modjy_servlet";
protected final static String LIB_PYTHON = "/WEB-INF/lib-python";
protected final static String PTH_FILE_EXTENSION = ".pth";
protected final static String LOAD_SITE_PACKAGES_PARAM = "load_site_packages";
protected final static String PYTHON_HOME_PARAM = "python.home";
protected PythonInterpreter interp;
protected HttpServlet modjyServlet;
/**
* Read configuration
* 1. Both context and servlet parameters are included in the set, so that
* the definition of some parameters (e.g python.*) can be shared between multiple WSGI
* servlets.
* 2. servlet params take precedence over context parameters
*/
protected Properties readConfiguration() {
Properties props = new Properties();
// Context parameters
ServletContext context = getServletContext();
Enumeration e = context.getInitParameterNames();
while (e.hasMoreElements()) {
String name = (String)e.nextElement();
props.put(name, context.getInitParameter(name));
}
// Servlet parameters override context parameters
e = getInitParameterNames();
while (e.hasMoreElements()) {
String name = (String)e.nextElement();
props.put(name, getInitParameter(name));
}
// Check if python home is relative, in which case find it in the servlet context
String pythonHomeString = props.getProperty(PYTHON_HOME_PARAM);
if (pythonHomeString != null) {
File pythonHome = new File(pythonHomeString);
if (!pythonHome.isAbsolute())
pythonHomeString = context.getRealPath(pythonHomeString);
props.setProperty(PYTHON_HOME_PARAM, pythonHomeString);
}
return props;
}
/**
* Initialise the modjy servlet.
* 1. Read the configuration
* 2. Initialise the jython runtime
* 3. Setup, in relation to the J2EE servlet environment
* 4. Create the jython-implemented servlet
* 5. Initialise the jython-implemented servlet
*/
@Override
public void init() throws ServletException {
try {
Properties props = readConfiguration();
// We check for site packages settings before initialising the runtime
// https://hg.python.org/jython/rev/51b28cc2c43d
checkSitePackages(props);
PythonInterpreter.initialize(System.getProperties(), props, new String[0]);
PySystemState systemState = new PySystemState();
interp = new PythonInterpreter(null, systemState);
setupEnvironment(interp, props, systemState);
try {
interp.exec("from modjy.modjy import " + MODJY_PYTHON_CLASSNAME);
} catch (PyException ix) {
throw new ServletException("Unable to import '" + MODJY_PYTHON_CLASSNAME
+ "': maybe you need to set the '" + PYTHON_HOME_PARAM + "' parameter?", ix);
}
PyObject pyServlet = ((PyType)interp.get(MODJY_PYTHON_CLASSNAME)).__call__();
Object temp = pyServlet.__tojava__(HttpServlet.class);
if (temp == Py.NoConversion)
throw new ServletException("Corrupted modjy file: cannot find definition of '"
+ MODJY_PYTHON_CLASSNAME + "' class");
modjyServlet = (HttpServlet)temp;
modjyServlet.init(this);
} catch (PyException pyx) {
throw new ServletException("Exception creating modjy servlet: " + pyx.toString(), pyx);
}
}
/**
* Actually service the incoming request. Simply delegate to the jython servlet.
*
* @param req
* - The incoming HttpServletRequest
* @param resp
* - The outgoing HttpServletResponse
*/
@Override
public void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException,
IOException {
modjyServlet.service(req, resp);
}
/**
* Close down the modjy servlet.
*
*/
@Override
public void destroy( ) {
interp.cleanup();
}
/**
* Setup the modjy environment, i.e.
* 1. Find the location of the modjy.jar file and add it to sys.path
* 2. Process the WEB-INF/lib-python directory, if it exists
*
* @param interp
* - The PythonInterpreter used to service requests
* @param props
* - The properties from which config options are found
* @param systemState
* - The PySystemState corresponding to the interpreter servicing requests
*/
protected void setupEnvironment(PythonInterpreter interp,
Properties props,
PySystemState systemState) throws PyException {
processPythonLib(interp, systemState);
}
/**
* Check if the user has requested to initialise the jython installation "site-packages".
* The value defaults to true, i.e. load site packages
*
* @param props
* - The properties from which config options are found
*/
protected void checkSitePackages(Properties props) throws PyException {
boolean loadSitePackages = true;
String loadSitePackagesParam = props.getProperty(LOAD_SITE_PACKAGES_PARAM);
if (loadSitePackagesParam != null && loadSitePackagesParam.trim().compareTo("0") == 0) {
loadSitePackages = false;
}
Options.importSite = loadSitePackages;
}
/**
* Do all processing in relation to the lib-python subdirectory of WEB-INF
*
* @param interp
* - The PythonInterpreter used to service requests
* @param systemState
* - The PySystemState whose path should be updated
*/
protected void processPythonLib(PythonInterpreter interp, PySystemState systemState) {
// Add the lib-python directory to sys.path
String pythonLibPath = getServletContext().getRealPath(LIB_PYTHON);
if (pythonLibPath == null) {
return;
}
File pythonLib = new File(pythonLibPath);
if (!pythonLib.exists()) {
return;
}
systemState.path.append(new PyString(pythonLibPath));
// Now check for .pth files in lib-python and process each one
String[] libPythonContents = pythonLib.list();
for (String libPythonContent : libPythonContents) {
if (libPythonContent.endsWith(PTH_FILE_EXTENSION)) {
processPthFile(interp, systemState, pythonLibPath, libPythonContent);
}
}
}
/**
* Process an individual file .pth file in the lib-python directory
*
* @param interp
* - The PythonInterpreter which will execute imports
* @param systemState
* - The PySystemState whose path should be updated
* @param pythonLibPath
* - The actual path to the lib-python directory
* @param pthFilename
* - The PySystemState whose path should be updated
*/
protected void processPthFile(PythonInterpreter interp,
PySystemState systemState,
String pythonLibPath,
String pthFilename) {
try {
LineNumberReader lineReader = new LineNumberReader(new FileReader(new File(pythonLibPath,
pthFilename)));
String line;
while ((line = lineReader.readLine()) != null) {
line = line.trim();
if (line.length() == 0) {
continue;
}
if (line.startsWith("#")) {
continue;
}
if (line.startsWith("import")) {
interp.exec(line);
continue;
}
File archiveFile = new File(pythonLibPath, line);
String archiveRealpath = archiveFile.getAbsolutePath();
systemState.path.append(new PyString(archiveRealpath));
}
} catch (IOException iox) {
System.err.println("IOException: " + iox.toString());
}
}
}