HtmlResourceHandler.java
/*
** Module : HtmlResourceHandler.java
** Abstract : delivers main page to AJAX clients
**
** Copyright (c) 2013-2023, Golden Code Development Corporation.
**
** -#- -I- --Date-- ----------------------Description--------------------------
** 001 MAG 20131105 First version based on jetty 9.1
** 002 MAG 20140206 Set Cache-Control header.
** 003 SBI 20180405 Changed to use template key and value provider.
** 004 SBI 20191120 Changed to specify UTF-8 encoding to read html templates.
** 005 GBB 20230512 Logging methods replaced by CentralLogger/ConversionStatus.
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 of the
** License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
**
** Additional terms under GNU Affero GPL version 3 section 7:
**
** Under Section 7 of the GNU Affero GPL version 3, the following additional
** terms apply to the works covered under the License. These additional terms
** are non-permissive additional terms allowed under Section 7 of the GNU
** Affero GPL version 3 and may not be removed by you.
**
** 0. Attribution Requirement.
**
** You must preserve all legal notices or author attributions in the covered
** work or Appropriate Legal Notices displayed by works containing the covered
** work. You may not remove from the covered work any author or developer
** credit already included within the covered work.
**
** 1. No License To Use Trademarks.
**
** This license does not grant any license or rights to use the trademarks
** Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
** of Golden Code Development Corporation. You are not authorized to use the
** name Golden Code, FWD, or the names of any author or contributor, for
** publicity purposes without written authorization.
**
** 2. No Misrepresentation of Affiliation.
**
** You may not represent yourself as Golden Code Development Corporation or FWD.
**
** You may not represent yourself for publicity purposes as associated with
** Golden Code Development Corporation, FWD, or any author or contributor to
** the covered work, without written authorization.
**
** 3. No Misrepresentation of Source or Origin.
**
** You may not represent the covered work as solely your work. All modified
** versions of the covered work must be marked in a reasonable way to make it
** clear that the modified work is not originating from Golden Code Development
** Corporation or FWD. All modified versions must contain the notices of
** attribution required in this license.
*/
package com.goldencode.p2j.web;
import java.io.*;
import java.util.HashMap;
import java.util.Map;
import java.util.function.Supplier;
import java.util.logging.*;
import javax.servlet.*;
import javax.servlet.http.*;
import com.goldencode.p2j.util.logging.*;
import org.eclipse.jetty.http.*;
import org.eclipse.jetty.server.handler.*;
import org.eclipse.jetty.server.*;
import com.goldencode.p2j.util.*;
/**
* jetty Handler which delivers HTML resource files.
* This class provide a method to parse the HTML text and
* substitute placeholder's.
*/
public abstract class HtmlResourceHandler
extends AbstractHandler
{
/** Logger. */
private static final CentralLogger LOG = CentralLogger.get(HtmlResourceHandler.class.getName());
/** The root portion of the target request name (part of the URL). */
private String targetRoot = null;
/** The html skeleton page. */
private String skeletonPage = null;
/**
* Constructor.
*
* @param targetRoot
* Prefix for all URLs relating to this page.
* @param skeletonPage
* Fully qualified resource name of the HTML file which should be used.
*/
public HtmlResourceHandler(String targetRoot, String skeletonPage)
{
this.targetRoot = targetRoot;
this.skeletonPage = skeletonPage;
}
/**
* Return the main page for AJAX clients.
*
* @param target
* The target of the request - either a URI or a name.
* @param base
* The base request.
* @param request
* The object or a wrapper of the request.
* @param response
* The object or a wrapper of the response.
*/
public void handle(String target,
Request base,
HttpServletRequest request,
HttpServletResponse response)
throws IOException,
ServletException
{
if (!base.isHandled() && target.equalsIgnoreCase(targetRoot))
{
generateMainPage(base, response);
}
}
/**
* Use the skeleton main page to generate a response.
*
* @param base
* The details and state the request.
* @param response
* The details and state of the response.
*
* @throws IOException
* ServletException
* If any error conditions occur.
*/
private void generateMainPage(Request base, HttpServletResponse response)
throws IOException,
ServletException
{
// produce the page contents
response.setContentType(MimeTypes.Type.TEXT_HTML.asString());
response.setStatus(HttpServletResponse.SC_OK);
response.setHeader(HttpHeader.CACHE_CONTROL.asString(),
"no-cache, no-store, must-revalidate");
response.setDateHeader(HttpHeader.EXPIRES.asString(), 0); // Proxies.
PrintWriter writer = response.getWriter();
Map<String, Supplier<String>> templateKeys = getTemplateKeys(base);
try
{
InputStream is = this.getClass().getResourceAsStream(skeletonPage);
TemplateHelper.fill(is, templateKeys, writer, "UTF-8");
}
catch (IOException ioe)
{
LOG.logp(Level.SEVERE,
"HtmlResourceHandler.generateMainPage()",
"",
"IOException!",
ioe);
}
finally
{
// mark the request as handled
base.setHandled(true);
}
}
/**
* Generates a map of template keys with their value suppliers in order to fill gaps in
* the html skeleton template page.
*
* @param base
* The request
*
* @return The target map of template keys with their value suppliers
*/
protected abstract Map<String, Supplier<String>> getTemplateKeys(Request base);
/**
* Holds a map of template keys with their value suppliers.
*/
protected class HtmlTemplateKeysProvider
{
/** The map of template keys with their value suppliers */
private final Map<String, Supplier<String>> templateKeys;
/** The request */
private final Request request;
/**
* Creates this html template keys provider.
*
* @param request
* The request
*/
public HtmlTemplateKeysProvider(Request request)
{
this.request = request;
this.templateKeys = new HashMap<>();
}
/**
* Returns the request associated with this html template keys provider.
*
* @return The request
*/
public Request getRequest()
{
return request;
}
/**
* Returns the map of template keys with their value suppliers.
*
* @return The map of template keys with their value suppliers
*/
public Map<String, Supplier<String>> getTemplateKeys()
{
return templateKeys;
}
/**
* Add new key and its value provider.
*
* @param key
* The key
* @param getter
* The value provider
*/
public void add(String key, Supplier<String> getter)
{
templateKeys.put(key, getter);
}
}
}