jgit/org.eclipse.jgit.http.server/src/org/eclipse/jgit/http/server/glue/MetaServlet.java

/*
 * Copyright (C) 2009-2010, Google Inc.
 * and other copyright owners as documented in the project's IP log.
 *
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Distribution License v1.0 which
 * accompanies this distribution, is reproduced below, and is
 * available at http://www.eclipse.org/org/documents/edl-v10.php
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 * - Neither the name of the Eclipse Foundation, Inc. nor the
 *   names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.eclipse.jgit.http.server.glue;

import static javax.servlet.http.HttpServletResponse.SC_NOT_FOUND;

import java.io.IOException;

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

/**
 * Generic container servlet to manage routing to different pipelines.
 * <p>
 * Callers can create and configure a new processing pipeline by using one of
 * the {@link #serve(String)} or {@link #serveRegex(String)} methods to allocate
 * a binder for a particular URL pattern.
 * <p>
 * Registered filters and servlets are initialized lazily, usually during the
 * first request. Once initialized the bindings in this servlet cannot be
 * modified without destroying the servlet and thereby destroying all registered
 * filters and servlets.
 */
public class MetaServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	private final MetaFilter filter;

	/** Empty servlet with no bindings. */
	public MetaServlet() {
		this(new MetaFilter());
	}

	/**
	 * Initialize a servlet wrapping a filter.
	 *
	 * @param delegateFilter
	 *            the filter being wrapped by the servlet.
	 */
	protected MetaServlet(MetaFilter delegateFilter) {
		filter = delegateFilter;
	}

	/** @return filter this servlet delegates all routing logic to. */
	protected MetaFilter getDelegateFilter() {
		return filter;
	}

	/**
	 * Construct a binding for a specific path.
	 *
	 * @param path
	 *            pattern to match.
	 * @return binder for the passed path.
	 */
	public ServletBinder serve(String path) {
		return filter.serve(path);
	}

	/**
	 * Construct a binding for a regular expression.
	 *
	 * @param expression
	 *            the regular expression to pattern match the URL against.
	 * @return binder for the passed expression.
	 */
	public ServletBinder serveRegex(String expression) {
		return filter.serveRegex(expression);
	}

	@Override
	public void init(ServletConfig config) throws ServletException {
		String name = filter.getClass().getName();
		ServletContext ctx = config.getServletContext();
		filter.init(new NoParameterFilterConfig(name, ctx));
	}

	@Override
	public void destroy() {
		filter.destroy();
	}

	@Override
	protected void service(HttpServletRequest req, HttpServletResponse res)
			throws ServletException, IOException {
		filter.doFilter(req, res, new FilterChain() {
			@Override
			public void doFilter(ServletRequest request,
					ServletResponse response) throws IOException,
					ServletException {
				((HttpServletResponse) response).sendError(SC_NOT_FOUND);
			}
		});
	}

	/**
	 * Configure a newly created binder.
	 *
	 * @param b
	 *            the newly created binder.
	 * @return binder for the caller, potentially after adding one or more
	 *         filters into the pipeline.
	 */
	protected ServletBinder register(ServletBinder b) {
		return filter.register(b);
	}
}