org.apache.http
Interface HttpEntity
- All Known Subinterfaces:
- ConsumingNHttpEntity, HttpNIOEntity, ProducingNHttpEntity
- All Known Implementing Classes:
- AbstractHttpEntity, BasicHttpEntity, BufferedHttpEntity, BufferingNHttpEntity, ByteArrayEntity, ByteArrayNIOEntity, ConsumingNHttpEntityTemplate, ContentBufferEntity, EntityTemplate, FileEntity, FileNIOEntity, HttpEntityWrapper, InputStreamEntity, NByteArrayEntity, NFileEntity, NHttpEntityWrapper, NStringEntity, SerializableEntity, StringEntity, StringNIOEntity
public interface HttpEntity
An entity that can be sent or received with an HTTP message.
Entities can be found in some
requests
and in
responses
, where they are optional.
In some places, the JavaDoc distinguishes three kinds of entities,
depending on where their content
originates:
- streamed: The content is received from a stream, or
generated on the fly. In particular, this category includes
entities being received from a
connection
.
Streamed
entities are generally not
repeatable
.
- self-contained: The content is in memory or obtained by
means that are independent from a connection or other entity.
Self-contained entities are generally
repeatable
.
- wrapping: The content is obtained from another entity.
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.
- Since:
- 4.0
- Version:
- $Revision: 645824 $
- Author:
- Oleg Kalnichevski
Method Summary |
void |
consumeContent()
TODO: The name of this method is misnomer. |
java.io.InputStream |
getContent()
Creates a new InputStream object of the entity. |
Header |
getContentEncoding()
Obtains the Content-Encoding header, if known. |
long |
getContentLength()
Tells the length of the content, if known. |
Header |
getContentType()
Obtains the Content-Type header, if known. |
boolean |
isChunked()
Tells about chunked encoding for this entity. |
boolean |
isRepeatable()
Tells if the entity is capable to produce its data more than once. |
boolean |
isStreaming()
Tells whether this entity depends on an underlying stream. |
void |
writeTo(java.io.OutputStream outstream)
Writes the entity content to the output stream. |
isRepeatable
boolean isRepeatable()
- 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.
- Returns:
- true if the entity is repeatable, false otherwise.
isChunked
boolean isChunked()
- 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.
The behavior of wrapping entities is implementation dependent,
but should respect the primary purpose.
- Returns:
true
if chunked encoding is preferred for this
entity, or false
if it is not
getContentLength
long getContentLength()
- Tells the length of the content, if known.
- Returns:
- the number of bytes of the content, or
a negative number if unknown. If the content length is known
but exceeds
Long.MAX_VALUE
,
a negative number is returned.
getContentType
Header getContentType()
- 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.
- Returns:
- the Content-Type header for this entity, or
null
if the content type is unknown
getContentEncoding
Header getContentEncoding()
- 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.
- Returns:
- the Content-Encoding header for this entity, or
null
if the content encoding is unknown
getContent
java.io.InputStream getContent()
throws java.io.IOException,
java.lang.IllegalStateException
- 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
repeatable
will throw an exception if this method is called multiple times.
- Returns:
- a new input stream that returns the entity data.
- Throws:
java.io.IOException
- if the stream could not be created
java.lang.IllegalStateException
- if this entity is not repeatable and the stream
has already been obtained previously
writeTo
void writeTo(java.io.OutputStream outstream)
throws java.io.IOException
- Writes the entity content to the output stream.
- Parameters:
outstream
- the output stream to write entity content to
- Throws:
java.io.IOException
- if an I/O error occurs
isStreaming
boolean isStreaming()
- Tells whether this entity depends on an underlying stream.
Streamed entities should return
true
until the
content has been consumed, false
afterwards.
Self-contained entities should return false
.
Wrapping entities should delegate this call to the wrapped entity.
The content of a streamed entity is consumed when the stream
returned by getContent
has been read to EOF,
or after consumeContent
has been called.
If a streamed entity can not detect whether the stream has been
read to EOF, it should return true
until
consumeContent
is called.
- Returns:
true
if the entity content is streamed and
not yet consumed, false
otherwise
consumeContent
void consumeContent()
throws java.io.IOException
- TODO: The name of this method is misnomer. It will be renamed to
#finish() in the next major release.
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.
This method is of particular importance for entities being
received from a connection
. The entity
needs to be consumed completely in order to re-use the connection
with keep-alive.
- Throws:
java.io.IOException
- if an I/O error occurs.
This indicates that connection keep-alive is not possible.
Copyright © 2005-2008 Apache Software Foundation. All Rights Reserved.