org.apache.http

Interface HttpEntity

All Known Implementing Classes:

AbstractHttpEntity, BasicHttpEntity, BufferedHttpEntity, ByteArrayEntity, EntityTemplate, FileEntity, HttpEntityWrapper, InputStreamEntity, SerializableEntity, StringEntity

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.

There are three distinct types of entities in HttpCore, 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

Method Summary

Methods

Modifier and Type	Method and Description
void	consumeContent() Deprecated. (4.1) Use EntityUtils.consume(HttpEntity)
InputStream	getContent() Returns a content stream 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 of producing its data more than once.
boolean	isStreaming() Tells whether this entity depends on an underlying stream.
void	writeTo(OutputStream outstream) Writes the entity content out to the output stream.

Method Detail

isRepeatable

boolean isRepeatable()

Tells if the entity is capable of producing 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

InputStream getContent()
                       throws IOException,
                              UnsupportedOperationException

Returns a content stream of the entity. Repeatable entities are expected to create a new instance of InputStream for each invocation of this method and therefore can be consumed multiple times. Entities that are not repeatable are expected to return the same InputStream instance and therefore may not be consumed more than once.

IMPORTANT: Please note all entity implementations must ensure that all allocated resources are properly deallocated after the InputStream.close() method is invoked.

Returns:

content stream of the entity.

Throws:

IOException - if the stream could not be created

UnsupportedOperationException - if entity content cannot be represented as InputStream.

See Also:

isRepeatable()

writeTo

void writeTo(OutputStream outstream)
             throws IOException

Writes the entity content out to the output stream.

IMPORTANT: Please note all entity implementations must ensure that all allocated resources are properly deallocated when this method returns.

Parameters:

outstream - the output stream to write entity content to

Throws:

IOException - if an I/O error occurs

isStreaming

boolean isStreaming()

Tells whether this entity depends on an underlying stream. Streamed entities that read data directly from the socket should return true. Self-contained entities should return false. Wrapping entities should delegate this call to the wrapped entity.

Returns:

true if the entity content is streamed, false otherwise

consumeContent

@Deprecated
void consumeContent()
                    throws IOException

Deprecated. (4.1) Use EntityUtils.consume(HttpEntity)

This method is deprecated since version 4.1. Please use standard java convention to ensure resource deallocation by calling InputStream.close() on the input stream returned by getContent()

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:

IOException - if an I/O error occurs.

See Also:

and #writeTo(OutputStream)