1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
|
/*
* $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/HttpEntity.java $
* $Revision: 645824 $
* $Date: 2008-04-08 03:12:41 -0700 (Tue, 08 Apr 2008) $
*
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/
package org.apache.http;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/**
* An entity that can be sent or received with an HTTP message.
* Entities can be found in some
* {@link HttpEntityEnclosingRequest requests} and in
* {@link HttpResponse responses}, where they are optional.
* <p>
* In some places, the JavaDoc distinguishes three kinds of entities,
* depending on where their {@link #getContent content} originates:
* <ul>
* <li><b>streamed</b>: The content is received from a stream, or
* generated on the fly. In particular, this category includes
* entities being received from a {@link HttpConnection connection}.
* {@link #isStreaming Streamed} entities are generally not
* {@link #isRepeatable repeatable}.
* </li>
* <li><b>self-contained</b>: The content is in memory or obtained by
* means that are independent from a connection or other entity.
* Self-contained entities are generally {@link #isRepeatable repeatable}.
* </li>
* <li><b>wrapping</b>: The content is obtained from another entity.
* </li>
* </ul>
* This distinction is important for connection management with incoming
* entities. For entities that are created by an application and only sent
* using the HTTP components framework, the difference between streamed
* and self-contained is of little importance. In that case, it is suggested
* to consider non-repeatable entities as streamed, and those that are
* repeatable (without a huge effort) as self-contained.
*
* @author <a href="mailto:oleg at ural.ru">Oleg Kalnichevski</a>
*
* @version $Revision: 645824 $
*
* @since 4.0
*/
public interface HttpEntity {
/**
* Tells if the entity is capable to produce its data more than once.
* A repeatable entity's getContent() and writeTo(OutputStream) methods
* can be called more than once whereas a non-repeatable entity's can not.
* @return true if the entity is repeatable, false otherwise.
*/
boolean isRepeatable();
/**
* Tells about chunked encoding for this entity.
* The primary purpose of this method is to indicate whether
* chunked encoding should be used when the entity is sent.
* For entities that are received, it can also indicate whether
* the entity was received with chunked encoding.
* <br/>
* The behavior of wrapping entities is implementation dependent,
* but should respect the primary purpose.
*
* @return <code>true</code> if chunked encoding is preferred for this
* entity, or <code>false</code> if it is not
*/
boolean isChunked();
/**
* Tells the length of the content, if known.
*
* @return the number of bytes of the content, or
* a negative number if unknown. If the content length is known
* but exceeds {@link java.lang.Long#MAX_VALUE Long.MAX_VALUE},
* a negative number is returned.
*/
long getContentLength();
/**
* Obtains the Content-Type header, if known.
* This is the header that should be used when sending the entity,
* or the one that was received with the entity. It can include a
* charset attribute.
*
* @return the Content-Type header for this entity, or
* <code>null</code> if the content type is unknown
*/
Header getContentType();
/**
* Obtains the Content-Encoding header, if known.
* This is the header that should be used when sending the entity,
* or the one that was received with the entity.
* Wrapping entities that modify the content encoding should
* adjust this header accordingly.
*
* @return the Content-Encoding header for this entity, or
* <code>null</code> if the content encoding is unknown
*/
Header getContentEncoding();
/**
* Creates a new InputStream object of the entity.
* It is a programming error
* to return the same InputStream object more than once.
* Entities that are not {@link #isRepeatable repeatable}
* will throw an exception if this method is called multiple times.
*
* @return a new input stream that returns the entity data.
*
* @throws IOException if the stream could not be created
* @throws IllegalStateException
* if this entity is not repeatable and the stream
* has already been obtained previously
*/
InputStream getContent() throws IOException, IllegalStateException;
/**
* Writes the entity content to the output stream.
*
* @param outstream the output stream to write entity content to
*
* @throws IOException if an I/O error occurs
*/
void writeTo(OutputStream outstream) throws IOException;
/**
* Tells whether this entity depends on an underlying stream.
* Streamed entities should return <code>true</code> until the
* content has been consumed, <code>false</code> afterwards.
* Self-contained entities should return <code>false</code>.
* Wrapping entities should delegate this call to the wrapped entity.
* <br/>
* The content of a streamed entity is consumed when the stream
* returned by {@link #getContent getContent} has been read to EOF,
* or after {@link #consumeContent consumeContent} has been called.
* If a streamed entity can not detect whether the stream has been
* read to EOF, it should return <code>true</code> until
* {@link #consumeContent consumeContent} is called.
*
* @return <code>true</code> if the entity content is streamed and
* not yet consumed, <code>false</code> otherwise
*/
boolean isStreaming(); // don't expect an exception here
/**
* TODO: The name of this method is misnomer. It will be renamed to
* #finish() in the next major release.
* <br/>
* This method is called to indicate that the content of this entity
* is no longer required. All entity implementations are expected to
* release all allocated resources as a result of this method
* invocation. Content streaming entities are also expected to
* dispose of the remaining content, if any. Wrapping entities should
* delegate this call to the wrapped entity.
* <br/>
* This method is of particular importance for entities being
* received from a {@link HttpConnection connection}. The entity
* needs to be consumed completely in order to re-use the connection
* with keep-alive.
*
* @throws IOException if an I/O error occurs.
* This indicates that connection keep-alive is not possible.
*/
void consumeContent() throws IOException;
} // interface HttpEntity
|
