Package org.apache.http

Interface HttpEntity

All Known Implementing Classes:
AbstractHttpEntity, BasicHttpEntity, BasicManagedEntity, BufferedHttpEntity, ByteArrayEntity, EntityTemplate, FileEntity, HttpEntityWrapper, InputStreamEntity, SerializableEntity, StringEntity, UrlEncodedFormEntity
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

    Modifier and Type Method Description
    void consumeContent()
    TODO: The name of this method is misnomer.
    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​(OutputStream outstream)
    Writes the entity content to the output stream.

  • Method Details

    • 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

      InputStream getContent() throws IOException, 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:
      IOException - if the stream could not be created
      IllegalStateException - if this entity is not repeatable and the stream has already been obtained previously

    • writeTo

      void writeTo​(OutputStream outstream) throws IOException
      Writes the entity content to the output stream.
      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 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 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:
      IOException - if an I/O error occurs. This indicates that connection keep-alive is not possible.