jsploaderservlet.java

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/* JspLoaderServlet.java

{{IS_NOTE
	Purpose:
		
	Description:
		
	History:
		Tue Nov 12 17:49:51  2002, Created by andrewho
		Nov 15 11:20 2002, Modified by tomyeh
}}IS_NOTE

Copyright (C) 2002 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
	This program is distributed under GPL Version 2.0 in the hope that
	it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.web.servlet.jsp;

import java.util.Iterator;
import java.util.Map;
import java.io.IOException;

import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.zkoss.lang.D;
import org.zkoss.lang.Classes;
import org.zkoss.util.CacheMap;
import org.zkoss.util.logging.Log;
import org.zkoss.util.WaitLock;

import org.zkoss.web.servlet.http.Https;

/**
 * JspLoaderServlet Load the compiled JSP pages.
 * @author andrewho
 */
public final class JspLoaderServlet extends HttpServlet {
	private static final Log log = Log.lookup(JspLoaderServlet.class);
	
	/** The jsp page associated with the compiled jsp page class. */
	private final Map _jspServlets = new JspCache();

	//--Constructor--
	public JspLoaderServlet() {
	}
    
	/**Get the compiled jsp servlet class.
	 * @param servletPath The servet path.
	 * @return Servlet The compiled jsp servlet class.
	 */
	public final Servlet getJspServlet(final String servletPath) 
	throws ServletException {
		WaitLock lock = null;
		for (;;) {
			final Object o;
			synchronized (_jspServlets) {	
				o = _jspServlets.get(servletPath);
				if (o == null)
					_jspServlets.put(servletPath, lock = new WaitLock()); //lock it
			}

			if (o instanceof Servlet)
				return (Servlet)o;
			if (o == null)
				break; //go to load the page

			//wait because some one is creating the servlet
			if (!((WaitLock)o).waitUntilUnlock(5*60*1000))
				log.warning("Take too long to wait loading JSP: "+servletPath
					+"\nTry to load this page again automatically...");
		} //for(;;)

		try {
			//get the class name
			final String className = Jsps.mapJspToJavaName(servletPath);
			if (D.ON && log.finerable())
				log.finer("Loading jsp: " + className + " path=" + servletPath);

			//Initial the class
			//final long time = System.currentTimeMillis();
			final Servlet servlet = (Servlet)
					Classes.newInstanceByThread(className);
			//log.info(className+" loaded in "+(System.currentTimeMillis()-time+500)/1000+" seconds.");
			servlet.init( getServletConfig() );	//just init it

			//add to map
			synchronized (_jspServlets) {
				_jspServlets.put(servletPath, servlet);
			}

			//if (D.ON && log.finerable()) log.finer("jsp loaded: " + className);
			return servlet;
		} catch (Throwable ex) {
			synchronized (_jspServlets) {
				_jspServlets.remove(servletPath);
			}
			if (ex instanceof RuntimeException)
				throw (RuntimeException)ex;
			if (ex instanceof Error)
				throw (Error)ex;
			if (ex instanceof ServletException)
				throw (ServletException)ex;
			throw new ServletException(ex);
		} finally {
			lock.unlock(); //unlock (always unlock to avoid deadlock)
		}
	}

	//-- HttpServlet --//
	protected void service(HttpServletRequest hreq, HttpServletResponse hres)
	throws IOException, ServletException {
		getJspServlet(Https.getThisServletPath(hreq)).service(hreq, hres);
	}

	public void destroy() {
		synchronized (_jspServlets) {
			for (Iterator it = _jspServlets.values().iterator(); it.hasNext();) {
				final Object val = it.next();
				if (val instanceof Servlet)
					((Servlet)val).destroy();
			}
			_jspServlets.clear();
		}
	}
	private static class JspCache extends CacheMap {
		JspCache() {
			setMaxSize(500);
			setLifetime(60*60*1000); //1hr
		}
		//-- super --//
		protected void onExpunge(Value v) {
			final Object val = v.getValue();
			if (val instanceof Servlet)
				((Servlet)val).destroy();
		}
	}
}