Hello World, How are we?

package org.python.util; import java.io.*; import java.util.*; import javax.servlet.*; import javax.servlet.http.*; import org.python.core.*; /** * This servlet is used to re-serve JPython servlets. It stores * bytecode for JPython servlets and re-uses it if the underlying .py * file has not changed. *

* Many people have been involved with this class: *

Chris Gokey *
David Syer *
Finn Bock *

* If somebody is missing from this list, let us know. *

* * e.g. http://localhost:8080/test/hello.py *

 *
 * from javax.servlet.http import HttpServlet
 * class hello(HttpServlet):
 *     def doGet(self, req, res):
 *         res.setContentType("text/html");
 *         out = res.getOutputStream()
 *         print >>out, ""
 *         print >>out, "Hello World, How are we?"
 *         print >>out, "Hello World, how are we?"
 *         print >>out, ""
 *         print >>out, ""
 *         out.close()
 *         return
 *

* * in web.xml for the PyServlet context: *

 * <web-app>
 *     <servlet>
 *         <servlet-name>PyServlet</servlet-name>
 *         <servlet-class>org.python.util.PyServlet</servlet-class>
 *         <init-param>
 *             <param-name>python.home</param-name>
 *             <param-value>/usr/home/jython-2.1</param-value>
 *         </init-param>
 *     </servlet>
 *     <servlet-mapping>
 *         <servlet-name>PyServlet</servlet-name>
 *         <url-pattern>*.py</url-pattern>
 *     </servlet-mapping>
 * </web-app>
 *
 *

*/ public class PyServlet extends HttpServlet { private PythonInterpreter interp; private Hashtable cache = new Hashtable(); private String rootPath; public void init() { rootPath = getServletContext().getRealPath("/"); if (!rootPath.endsWith(File.separator)) rootPath += File.separator; 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)); } // Config parameters e = getInitParameterNames(); while (e.hasMoreElements()) { String name = (String) e.nextElement(); props.put(name, getInitParameter(name)); } if (props.getProperty("python.home") == null && System.getProperty("python.home") == null) { props.put("python.home", rootPath + "WEB-INF" + File.separator + "lib"); } PythonInterpreter.initialize(System.getProperties(), props, new String[0]); reset(); PySystemState sys = Py.getSystemState(); sys.add_package("javax.servlet"); sys.add_package("javax.servlet.http"); sys.add_package("javax.servlet.jsp"); sys.add_package("javax.servlet.jsp.tagext"); sys.add_classdir(rootPath + "WEB-INF" + File.separator + "classes"); sys.add_extdir(rootPath + "WEB-INF" + File.separator + "lib", true); } /** * Implementation of the HttpServlet main method. * @param req the request parameter. * @param res the response parameter. * @exception ServletException * @exception IOException */ public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException { req.setAttribute("pyservlet", this); String spath = (String)req.getAttribute( "javax.servlet.include.servlet_path"); if (spath == null) { spath = ((HttpServletRequest) req).getServletPath(); if (spath == null || spath.length() == 0) { // Servlet 2.1 puts the path of an extension-matched // servlet in PathInfo. spath = ((HttpServletRequest) req).getPathInfo(); } } String rpath = getServletContext().getRealPath(spath); interp.set("__file__", rpath); HttpServlet servlet = getServlet(rpath); if (servlet != null) servlet.service(req, res); else throw new ServletException("No python servlet found at:" + spath); } public void reset() { destroyCache(); interp = new PythonInterpreter(null, new PySystemState()); cache.clear(); PySystemState sys = Py.getSystemState(); sys.path.append(new PyString(rootPath)); String modulesDir = rootPath + "WEB-INF" + File.separator + "jython"; sys.path.append(new PyString(modulesDir)); } private synchronized HttpServlet getServlet(String path) throws ServletException, IOException { CacheEntry entry = (CacheEntry) cache.get(path); if (entry == null) return loadServlet(path); File file = new File(path); if (file.lastModified() > entry.date) return loadServlet(path); return entry.servlet; } private HttpServlet loadServlet(String path) throws ServletException, IOException { HttpServlet servlet = null; File file = new File(path); // Extract servlet name from path (strip ".../" and ".py") int start = path.lastIndexOf(File.separator); if (start < 0) start = 0; else start++; int end = path.lastIndexOf('.'); if ((end < 0) || (end <= start)) end = path.length(); String name = path.substring(start, end); try { interp.execfile(path); PyObject cls = interp.get(name); if (cls == null) throw new ServletException("No callable (class or function) "+ "named " + name + " in " + path); PyObject pyServlet = cls.__call__(); Object o = pyServlet.__tojava__(HttpServlet.class); if (o == Py.NoConversion) throw new ServletException("The value from " + name + "must extend HttpServlet"); servlet = (HttpServlet)o; servlet.init(getServletConfig()); } catch (PyException e) { throw new ServletException("Could not create "+ "Jython servlet" + e.toString()); } CacheEntry entry = new CacheEntry(servlet, file.lastModified()); cache.put(path, entry); return servlet; } public void destroy() { destroyCache(); } private void destroyCache() { for (Enumeration e = cache.elements(); e.hasMoreElements(); ) { CacheEntry entry = (CacheEntry) e.nextElement(); entry.servlet.destroy(); } } } class CacheEntry { public long date; public HttpServlet servlet; CacheEntry(HttpServlet servlet, long date) { this.servlet= servlet; this.date = date; } }