1 /*

     2  * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package java.net.http;

    27 

    28 import java.util.List;

    29 import java.util.Map;

    30 import java.util.Optional;

    31 import java.util.OptionalLong;

    32 import static java.util.Collections.emptyList;

    33 import static java.util.Collections.unmodifiableList;

    34 import static java.util.Objects.requireNonNull;

    35 

    36 /**

    37  * A read-only view of a set of HTTP headers.

    38  *

    39  * <p> The methods of this class ( that accept a String header name ), and the

    40  * Map returned by the {@linkplain #map() map} method, operate without regard to

    41  * case when retrieving the header value.

    42  *

    43  * <p> HttpHeaders instances are immutable.

    44  *

    45  * @since 11

    46  */

    47 public abstract class HttpHeaders {

    48 

    49     /**

    50      * Creates an HttpHeaders.

    51      */

    52     protected HttpHeaders() {}

    53 

    54     /**

    55      * Returns an {@link Optional} containing the first value of the given named

    56      * (and possibly multi-valued) header. If the header is not present, then

    57      * the returned {@code Optional} is empty.

    58      *

    59      * @implSpec

    60      * The default implementation invokes

    61      * {@code allValues(name).stream().findFirst()}

    62      *

    63      * @param name the header name

    64      * @return an {@code Optional<String>} for the first named value

    65      */

    66     public Optional<String> firstValue(String name) {

    67         return allValues(name).stream().findFirst();

    68     }

    69 

    70     /**

    71      * Returns an {@link OptionalLong} containing the first value of the

    72      * named header field. If the header is not present, then the Optional is

    73      * empty. If the header is present but contains a value that does not parse

    74      * as a {@code Long} value, then an exception is thrown.

    75      *

    76      * @implSpec

    77      * The default implementation invokes

    78      * {@code allValues(name).stream().mapToLong(Long::valueOf).findFirst()}

    79      *

    80      * @param name the header name

    81      * @return  an {@code OptionalLong}

    82      * @throws NumberFormatException if a value is found, but does not parse as

    83      *                               a Long

    84      */

    85     public OptionalLong firstValueAsLong(String name) {

    86         return allValues(name).stream().mapToLong(Long::valueOf).findFirst();

    87     }

    88 

    89     /**

    90      * Returns an unmodifiable List of all of the values of the given named

    91      * header. Always returns a List, which may be empty if the header is not

    92      * present.

    93      *

    94      * @implSpec

    95      * The default implementation invokes, among other things, the

    96      * {@code map().get(name)} to retrieve the list of header values.

    97      *

    98      * @param name the header name

    99      * @return a List of String values

   100      */

   101     public List<String> allValues(String name) {

   102         requireNonNull(name);

   103         List<String> values = map().get(name);

   104         // Making unmodifiable list out of empty in order to make a list which

   105         // throws UOE unconditionally

   106         return values != null ? values : unmodifiableList(emptyList());

   107     }

   108 

   109     /**

   110      * Returns an unmodifiable multi Map view of this HttpHeaders.

   111      *

   112      * @return the Map

   113      */

   114     public abstract Map<String, List<String>> map();

   115 

   116     /**

   117      * Tests this HTTP headers instance for equality with the given object.

   118      *

   119      * <p> If the given object is not an {@code HttpHeaders} then this

   120      * method returns {@code false}. Two HTTP headers are equal if each

   121      * of their corresponding {@linkplain #map() maps} are equal.

   122      *

   123      * <p> This method satisfies the general contract of the {@link

   124      * Object#equals(Object) Object.equals} method.

   125      *

   126      * @param obj the object to which this object is to be compared

   127      * @return {@code true} if, and only if, the given object is an {@code

   128      *         HttpHeaders} that is equal to this HTTP headers

   129      */

   130     public final boolean equals(Object obj) {

   131         if (!(obj instanceof HttpHeaders))

   132             return false;

   133         HttpHeaders that = (HttpHeaders)obj;

   134         return this.map().equals(that.map());

   135     }

   136 

   137     /**

   138      * Computes a hash code for this HTTP headers instance.

   139      *

   140      * <p> The hash code is based upon the components of the HTTP headers

   141      * {@linkplain #map() map}, and satisfies the general contract of the

   142      * {@link Object#hashCode Object.hashCode} method.

   143      *

   144      * @return the hash-code value for this HTTP headers

   145      */

   146     public final int hashCode() {

   147         return map().hashCode();

   148     }

   149 

   150     /**

   151      * Returns this HTTP headers as a string.

   152      *

   153      * @return a string describing the HTTP headers

   154      */

   155     @Override

   156     public String toString() {

   157         StringBuilder sb = new StringBuilder();

   158         sb.append(super.toString()).append(" { ");

   159         sb.append(map());

   160         sb.append(" }");

   161         return sb.toString();

   162     }

   163 }