Class CharacterStreamDescriptor

java.lang.Object
org.apache.derby.iapi.jdbc.CharacterStreamDescriptor
public class CharacterStreamDescriptor extends Object
A description of a byte stream representing characters. The description is used by decoders to properly configure themselves. Note that encoding is not included in the description, because all internal byte streams are expected to be using the modified UTF-8 encoding (see DataInput).

The information in the description is only guaranteed to be valid at the moment it is passed to the decoder object. As the decoder works on the stream, the information in the descriptor will be outdated.

To create a stream descriptor, obtain a Builder instance and set the required parameters.

See Also:

  • Field Details

    • BEFORE_FIRST

      public static final long BEFORE_FIRST
      Constant for the character position, when it is positioned before the first character in the stream (i.e. at the very beginning of the stream or in the header).
      See Also:

    • dataOffset

      private final long dataOffset
      First data byte in the byte stream.

    • curBytePos

      private final long curBytePos
      The current byte position.

    • curCharPos

      private final long curCharPos
      The current character position.

    • byteLength

      private final long byteLength
      The byte length of the stream, 0 if unknown.

    • charLength

      private final long charLength
      The character length of the stream, 0 if unknown.

    • maxCharLength

      private final long maxCharLength
      The maximum allowed character length.

    • bufferable

      private final boolean bufferable
      Tells if the stream can be buffered or not.

    • positionAware

      private final boolean positionAware
      Tells if the stream is aware of its own position.

    • stream

      private final InputStream stream
      Reference to the stream we are describing.

  • Constructor Details

  • Method Details

    • isBufferable

      public boolean isBufferable()
      Tells if the described stream should be buffered or not.

      Some of the reasons a stream should not be buffered at this level, are the stream is already buffered, or it serves bytes directly from a byte array in memory.

      Returns:
      true if the stream should be buffered for improved performance, false if it should not be buffered.

    • isPositionAware

      public boolean isPositionAware()
      Tells if the described stream is aware of its own position, and that it can reposition itself on request.
      Returns:
      true if the stream is position aware, @{code false} otherwise.

    • getByteLength

      public long getByteLength()

    • getCharLength

      public long getCharLength()

    • getCurBytePos

      public long getCurBytePos()

    • getCurCharPos

      public long getCurCharPos()
      Returns the current character position.
      Returns:
      The current character position, where the first character is at position 1, or BEFORE_FIRST if the stream is positioned before the first character.

    • getDataOffset

      public long getDataOffset()
      Returns the first index of the described stream that contains real data.

      The information is typically used to filter out meta data at the head of the stream, and to correctly reset the stream.

      Returns:
      The first position in the stream containing real data.

    • getMaxCharLength

      public long getMaxCharLength()
      Returns the imposed maximum character length on the described stream.

      The default value is Long.MAX_VALUE.

      Returns:
      The max allowed character length of the stream, or 0 if no limit has been set.

    • getStream

      public InputStream getStream()
      Returns the associated stream.
      Returns:
      An InputStream reference.

    • getPositionedStream

      public PositionedStream getPositionedStream()
      Returns the associated positioned stream, if the stream is position aware.
      Returns:
      A PositionedStream reference.
      Throws:
      ClassCastException - if the stream cannot be cast to PositionedStream
      IllegalArgumentException - if the method is called and the assoicated stream isn't described as position aware.
      See Also:

    • toString

      public String toString()
      Overrides:
      toString in class Object