com.semanticcms.core.servlet.ServletElementContext Maven / Gradle / Ivy

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/*
 * semanticcms-core-servlet - Java API for modeling web page content and relationships in a Servlet environment.
 * Copyright (C) 2015, 2016  AO Industries, Inc.
 *     [email protected]
 *     7262 Bull Pen Cir
 *     Mobile, AL 36695
 *
 * This file is part of semanticcms-core-servlet.
 *
 * semanticcms-core-servlet is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * semanticcms-core-servlet 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with semanticcms-core-servlet.  If not, see .
 */
package com.semanticcms.core.servlet;

import com.aoindustries.lang.NotImplementedException;
import com.semanticcms.core.model.ElementContext;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.Writer;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;

/**
 * An ElementContext that is a ServletContext.
 */
public class ServletElementContext implements ElementContext {

	private final ServletContext servletContext;
	private final HttpServletRequest request;
	private final HttpServletResponse response;

	public ServletElementContext(
		ServletContext servletContext,
		HttpServletRequest request,
		HttpServletResponse response
	) {
		this.servletContext = servletContext;
		this.request = request;
		this.response = response;
	}

	@Override
	public void include(String resource, Writer out) throws IOException {
		try {
			final PrintWriter pw;
			if(out instanceof PrintWriter) pw = (PrintWriter)out;
			else pw = new PrintWriter(out);
			final RequestDispatcher dispatcher = servletContext.getRequestDispatcher(resource);
			// Clear PageContext on include
			PageContext.newPageContext(
				null,
				null,
				null,
				// Java 1.8: Lambda
				new PageContext.PageContextCallable() {
					@Override
					public void call() throws ServletException, IOException {
						dispatcher.include(
							request,
							new HttpServletResponseWrapper(response) {
								@Override
								public PrintWriter getWriter() {
									return pw;
								}
								@Override
								public ServletOutputStream getOutputStream() {
									throw new NotImplementedException();
								}
							}
						);
					}
				}
			);
			if(pw.checkError()) throw new IOException("Error on include PrintWriter");
		} catch(ServletException e) {
			throw new IOException(e);
		}
	}
}