interpreterservlet.java

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/* InterpreterServlet.java

{{IS_NOTE
	Purpose:
		
	Description:
		
	History:
		Mon Sep  5 17:06:34     2005, Created by tomyeh
}}IS_NOTE

Copyright (C) 2005 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.dsp;

import java.io.File;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.URL;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServlet;

import org.zkoss.lang.D;
import org.zkoss.lang.Exceptions;
import org.zkoss.util.logging.Log;
import org.zkoss.util.resource.ResourceCache;
import org.zkoss.util.resource.Locator;
import org.zkoss.io.Files;

import org.zkoss.web.servlet.Charsets;
import org.zkoss.web.servlet.http.Https;
import org.zkoss.web.util.resource.ResourceCaches;
import org.zkoss.web.util.resource.ResourceLoader;
import org.zkoss.web.util.resource.ServletContextLocator;

/**
 * The servlet used to interpret the DSP file (Potix Dynamic Script Page).
 *
 * <p>Initial parameters:
 * <dl>
 * <dt>charset</dt>
 * <dd>The default character set if not specified in the DSP page.
 * Default: UTF-8.</dd>
 * </dl>
 *
 * @author tomyeh
 */
public class InterpreterServlet extends HttpServlet {
	private static final Log log = Log.lookup(InterpreterServlet.class);
	private ServletContext _ctx;
	private String _charset = "UTF-8";

	public void init(ServletConfig config) throws ServletException {
		//super.init(config);
			//Note callback super to avoid saving config

		_ctx = config.getServletContext();

		final String cs = config.getInitParameter("charset");
		if (cs != null)
			_charset = cs.length() > 0 ? cs: null;
	}
	public ServletContext getServletContext() {
		return _ctx;
	}

	//-- super --//
	protected
	void doGet(HttpServletRequest request, HttpServletResponse response)
	throws ServletException, IOException {
		final String path = Https.getThisServletPath(request);
		if (D.ON && log.debugable()) log.debug("Get "+path);

		final Object old = Charsets.setup(request, response, _charset);
		try {
			final Interpretation cnt = (Interpretation)
				ResourceCaches.get(getCache(_ctx), _ctx, path, null);
			if (cnt == null) {
				if (Https.isIncluded(request)) log.error("Not found: "+path);
					//It might be eaten, so log the error
				response.sendError(HttpServletResponse.SC_NOT_FOUND);
				return;
			}
			cnt.interpret(
				new ServletDSPContext(_ctx, request, response, null));
		} finally {
			Charsets.cleanup(request, old);
		}
	}
	protected
	void doPost(HttpServletRequest request, HttpServletResponse response)
	throws ServletException, IOException {
		doGet(request, response);
	}

	private static final String ATTR_PAGE_CACHE = "org.zkoss.web.servlet.dsp.PageCache";
	private static final ResourceCache getCache(ServletContext ctx) {
		ResourceCache cache = (ResourceCache)ctx.getAttribute(ATTR_PAGE_CACHE);
		if (cache == null) {
			synchronized (InterpreterServlet.class) {
				cache = (ResourceCache)ctx.getAttribute(ATTR_PAGE_CACHE);
				if (cache == null) {
					cache = new ResourceCache(new MyLoader(ctx), 29);
					cache.setMaxSize(500).setLifetime(60*60*1000); //1hr
					ctx.setAttribute(ATTR_PAGE_CACHE, cache);
				}
			}
		}
		return cache;
	}
	private static class MyLoader extends ResourceLoader {
		private final Locator _locator;
		private MyLoader(ServletContext ctx) {
			_locator = new ServletContextLocator(ctx);
		}
		//-- super --//
		protected Object parse(String path, File file, Object extra)
		throws Exception {
			try {
				return parse0(new FileInputStream(file),
					Interpreter.getContentType(file.getName()));
			} catch (Exception ex) {
				if (log.debugable())
					log.realCauseBriefly("Failed to parse "+file, ex);
				else
					log.error("Failed to parse "+file+"\nCause: "+Exceptions.getMessage(ex)
						+"\n"+Exceptions.getFirstStackTrace(ex));
				return null; //as non-existent
			}
		}
		protected Object parse(String path, URL url, Object extra)
		throws Exception {
			try {
				return parse0(url.openStream(),
					Interpreter.getContentType(url.getPath()));
			} catch (Exception ex) {
				if (log.debugable())
					log.realCauseBriefly("Failed to parse "+url, ex);
				else
					log.error("Failed to parse "+url+"\nCause: "+Exceptions.getMessage(ex));
				return null; //as non-existent
			}
		}
		private Object parse0(InputStream is, String ctype) throws Exception {
			if (is == null) return null;

			final String content =
				Files.readAll(new InputStreamReader(is, "UTF-8"))
				.toString();
			return new Interpreter().parse(content, ctype, null, _locator);
		}
	}
}