com.isotrol.impe3.core.impl.HeadersFactory.java Source code

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Here is the source code for com.isotrol.impe3.core.impl.HeadersFactory.java

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/**
 * This file is part of Port@l
 * Port@l 3.0 - Portal Engine and Management System
 * Copyright (C) 2010  Isotrol, SA.  http://www.isotrol.com
 *
 * Port@l is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Port@l 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Port@l.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.isotrol.impe3.core.impl;

import java.util.Enumeration;
import java.util.List;
import java.util.Set;
import java.util.Map.Entry;

import javax.servlet.http.HttpServletRequest;
import javax.ws.rs.core.HttpHeaders;

import net.sf.derquinsej.CaseIgnoringString;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMultimap;
import com.google.common.collect.Multimap;
import com.isotrol.impe3.api.Headers;

/**
 * Factory class for different HTTP headers implementations.
 * @author Andres Rodriguez
 */
public final class HeadersFactory {
    /** Not instantiable. */
    private HeadersFactory() {
        throw new AssertionError();
    }

    private static final Empty EMPTY = new Empty();

    /**
     * Returns an empty collection of cookies.
     */
    public static Headers of() {
        return EMPTY;
    }

    /**
     * Adds the parameters from a servlet request.
     * @param request Servlet request.
     * @return The request parameters.
     */
    public static Headers of(HttpServletRequest request) {
        Preconditions.checkNotNull(request, "The request cannot be null.");
        final ImmutableMultimap.Builder<CaseIgnoringString, String> builder = ImmutableMultimap.builder();
        @SuppressWarnings("unchecked")
        final Enumeration<String> names = request.getHeaderNames();
        if (names != null) {
            while (names.hasMoreElements()) {
                final String header = names.nextElement();
                @SuppressWarnings("unchecked")
                final Enumeration<String> values = request.getHeaders(header);
                if (values != null && values.hasMoreElements()) {
                    final CaseIgnoringString cih = CaseIgnoringString.valueOf(header);
                    while (values.hasMoreElements()) {
                        builder.put(cih, values.nextElement());
                    }
                }
            }
        }
        return new Immutable(builder.build());
    }

    /**
     * Adds the parameters from a JAX-RS headers object.
     * @param headers HTTP Headers.
     * @return The request headers.
     */
    public static Headers of(HttpHeaders headers) {
        Preconditions.checkNotNull(headers, "The request headers object cannot be null.");
        final ImmutableMultimap.Builder<CaseIgnoringString, String> builder = ImmutableMultimap.builder();
        for (Entry<String, List<String>> entry : headers.getRequestHeaders().entrySet()) {
            List<String> values = entry.getValue();
            if (values != null) {
                builder.putAll(CaseIgnoringString.valueOf(entry.getKey()), values);
            }
        }
        return new Immutable(builder.build());
    }

    /**
     * Empty implementation.
     * @author Andres Rodriguez
     */
    private static final class Empty extends EmptyMultiStringParameters implements Headers {
        private Empty() {
        }

        public Headers subset(Set<String> included) {
            return this;
        }
    }

    /**
     * Immutable HTTP request params implementation.
     * @author Andres Rodriguez
     */
    private static final class Immutable extends AbstractMultiStringParameters.AbstractImmutable
            implements Headers {
        private Immutable(Multimap<CaseIgnoringString, String> headers) {
            super(headers);
        }

        public Headers subset(Set<String> included) {
            return new Immutable(submap(included));
        }
    }

}