Java tutorial
/* * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. * * Copyright (c) 2010-2013 Oracle and/or its affiliates. All rights reserved. * * The contents of this file are subject to the terms of either the GNU * General Public License Version 2 only ("GPL") or the Common Development * and Distribution License("CDDL") (collectively, the "License"). You * may not use this file except in compliance with the License. You can * obtain a copy of the License at * http://glassfish.java.net/public/CDDL+GPL_1_1.html * or packager/legal/LICENSE.txt. See the License for the specific * language governing permissions and limitations under the License. * * When distributing the software, include this License Header Notice in each * file and include the License file at packager/legal/LICENSE.txt. * * GPL Classpath Exception: * Oracle designates this particular file as subject to the "Classpath" * exception as provided by Oracle in the GPL Version 2 section of the License * file that accompanied this code. * * Modifications: * If applicable, add the following below the License Header, with the fields * enclosed by brackets [] replaced by your own identifying information: * "Portions Copyright [year] [name of copyright owner]" * * Contributor(s): * If you wish your version of this file to be governed by only the CDDL or * only the GPL Version 2, indicate your decision by adding "[Contributor] * elects to include this software in this distribution under the [CDDL or GPL * Version 2] license." If you don't indicate a single choice of license, a * recipient has the option to distribute your version of this file under * either the CDDL, the GPL Version 2 or to extend the choice of license to * its licensees as provided above. However, if you add GPL Version 2 code * and therefore, elected the GPL Version 2 license, then the option applies * only if the new code is made subject to such option by the copyright * holder. */ package org.glassfish.jersey.message.internal; import java.util.Collections; import java.util.Iterator; import java.util.List; import javax.ws.rs.core.AbstractMultivaluedMap; import javax.ws.rs.core.MultivaluedMap; import javax.ws.rs.ext.RuntimeDelegate; import javax.ws.rs.ext.RuntimeDelegate.HeaderDelegate; import org.glassfish.jersey.internal.util.collection.ImmutableMultivaluedMap; import org.glassfish.jersey.internal.util.collection.StringKeyIgnoreCaseMultivaluedMap; import com.google.common.base.Function; import com.google.common.collect.Lists; import com.google.common.collect.Maps; /** * Utility class supporting the processing of message headers. * * @author Marek Potociar (marek.potociar at oracle.com) * @author Michal Gajdos (michal.gajdos at oracle.com) */ public final class HeadersFactory { /** * Create an empty inbound message headers container. Created container is mutable. * * @return a new empty mutable container for storing inbound message headers. */ public static AbstractMultivaluedMap<String, String> createInbound() { return new StringKeyIgnoreCaseMultivaluedMap<String>(); } /** * Get immutable empty message headers container. The factory method can be * used to for both message header container types – inbound * as well as outbound. * * @param <V> header value type. Typically {@link Object} in case of the outbound * headers and {@link String} in case of the inbound headers. * @return an immutable empty message headers container. */ public static <V> MultivaluedMap<String, V> empty() { return ImmutableMultivaluedMap.empty(); } /** * Create an empty outbound message headers container. Created container is mutable. * * @return a new empty mutable container for storing outbound message headers. */ public static AbstractMultivaluedMap<String, Object> createOutbound() { return new StringKeyIgnoreCaseMultivaluedMap<Object>(); } /** * Convert a message header value, represented as a general object, to it's * string representation. If the supplied header value is {@code null}, * this method returns {@code null}. * <p> * This method defers to {@link RuntimeDelegate#createHeaderDelegate} to * obtain a {@link HeaderDelegate} to convert the value to a {@code String}. * If a {@link HeaderDelegate} is not found then the {@code toString()} * method on the header object is utilized. * * @param headerValue the header value represented as an object. * @param rd runtime delegate instance to be used for header delegate * retrieval. If {@code null}, a default {@code RuntimeDelegate} * instance will be {@link RuntimeDelegate#getInstance() obtained} and * used. * @return the string representation of the supplied header value or {@code null} * if the supplied header value is {@code null}. */ @SuppressWarnings("unchecked") public static String asString(final Object headerValue, RuntimeDelegate rd) { if (headerValue == null) { return null; } if (headerValue instanceof String) { return (String) headerValue; } if (rd == null) { rd = RuntimeDelegate.getInstance(); } final HeaderDelegate hp = rd.createHeaderDelegate(headerValue.getClass()); return (hp != null) ? hp.toString(headerValue) : headerValue.toString(); } /** * Returns string view of list of header values. Any modifications to the underlying list are visible to the view, * the view also supports removal of elements. Does not support other modifications. * * @param headerValues header values. * @param rd RuntimeDelegate instance or {@code null} (in that case {@link RuntimeDelegate#getInstance()} * will be called for before element conversion. * @return String view of header values. */ public static List<String> asStringList(final List<Object> headerValues, final RuntimeDelegate rd) { if (headerValues == null || headerValues.isEmpty()) { return Collections.emptyList(); } final RuntimeDelegate delegate; if (rd == null) { delegate = RuntimeDelegate.getInstance(); } else { delegate = rd; } return Lists.transform(headerValues, new Function<Object, String>() { @Override public String apply(Object input) { return (input == null) ? "[null]" : HeadersFactory.asString(input, delegate); } }); } /** * Returns string view of passed headers. Any modifications to the headers are visible to the view, the view also * supports removal of elements. Does not support other modifications. * * @param headers headers. * @return String view of headers or {@code null} if {code headers} input parameter is {@code null}. */ public static MultivaluedMap<String, String> asStringHeaders(final MultivaluedMap<String, Object> headers) { if (headers == null) { return null; } final RuntimeDelegate rd = RuntimeDelegate.getInstance(); return new AbstractMultivaluedMap<String, String>( Maps.transformValues(headers, new Function<List<Object>, List<String>>() { @Override public List<String> apply(List<Object> input) { return HeadersFactory.asStringList(input, rd); } })) { }; } /** * Converts a list of message header values to a single string value (with individual values separated by * {@code ','}). * * Each single header value is converted to String using a * {@link javax.ws.rs.ext.RuntimeDelegate.HeaderDelegate} if one is available * via {@link javax.ws.rs.ext.RuntimeDelegate#createHeaderDelegate(java.lang.Class)} * for the header value class or using its {@code toString()} method if a header * delegate is not available. * * @param values list of individual header values. * @param rd {@link RuntimeDelegate} instance or {@code null} (in that case {@link RuntimeDelegate#getInstance()} * will be called for before conversion of elements). * @return single string consisting of all the values passed in as a parameter. If values parameter is {@code null}, * {@code null} is returned. If the list of values is empty, an empty string is returned. */ public static String asHeaderString(List<Object> values, RuntimeDelegate rd) { if (values == null) { return null; } final Iterator<String> stringValues = asStringList(values, rd).iterator(); if (!stringValues.hasNext()) { return ""; } StringBuilder buffer = new StringBuilder(stringValues.next()); while (stringValues.hasNext()) { buffer.append(',').append(stringValues.next()); } return buffer.toString(); } /** * Preventing instantiation. */ private HeadersFactory() { } }