Class LOBInputStream

java.lang.Object
java.io.InputStream
org.apache.derby.impl.jdbc.LOBInputStream
All Implemented Interfaces:
Closeable, AutoCloseable, PositionedStream
public class LOBInputStream extends InputStream implements PositionedStream
This input stream is built on top of LOBStreamControl.

All the read methods are routed to LOBStreamControl.

  • Field Details

    • closed

      private boolean closed

    • control

      private final LOBStreamControl control

    • pos

      private long pos

    • updateCount

      private long updateCount

  • Constructor Details

  • Method Details

    • read

      public int read(byte[] b, int off, int len) throws IOException
      Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read. The number of bytes actually read is returned as an integer.

      This method blocks until input data is available, end of file is detected, or an exception is thrown.

      If b is null, a NullPointerException is thrown.

      If off is negative, or len is negative, or off+len is greater than the length of the array b, then an IndexOutOfBoundsException is thrown.

      If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

      The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected.

      In every case, elements b[0] through b[off] and elements b[off+len] through b[b.length-1] are unaffected.

      If the first byte cannot be read for any reason other than end of file, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed.

      The read(b, off, len) method for class InputStream simply calls the method read() repeatedly. If the first such call results in an IOException, that exception is returned from the call to the read(b, off, len) method. If any subsequent call to read() results in a IOException, the exception is caught and treated as if it were end of file; the bytes read up to that point are stored into b and the number of bytes read before the exception occurred is returned. Subclasses are encouraged to provide a more efficient implementation of this method.

      Overrides:
      read in class InputStream
      Parameters:
      b - the buffer into which the data is read.
      off - the start offset in array b at which the data is written.
      len - the maximum number of bytes to read.
      Returns:
      the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.
      Throws:
      IOException - if an I/O error occurs.
      NullPointerException - if b is null.
      See Also:

    • close

      public void close() throws IOException
      Closes this input stream and releases any system resources associated with the stream.

      The close method of InputStream does nothing.

      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Overrides:
      close in class InputStream
      Throws:
      IOException - if an I/O error occurs.

    • read

      public int read() throws IOException
      Reads the next byte of data from the input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

      A subclass must provide an implementation of this method.

      Specified by:
      read in class InputStream
      Returns:
      the next byte of data, or -1 if the end of the stream is reached.
      Throws:
      IOException - if an I/O error occurs.

    • isObsolete

      boolean isObsolete()
      Checks if underlying StreamControl has been updated.
      Returns:
      if stream is modified since created

    • reInitialize

      void reInitialize()
      Reinitializes the stream and sets the current pointer to zero.

    • length

      long length() throws IOException
      Returns size of stream in bytes.
      Returns:
      size of stream.
      Throws:
      IOException

    • asInputStream

      public InputStream asInputStream()
      Description copied from interface: PositionedStream
      Returns a reference to self as an InputStream.

      This method is not allowed to return null.

      Specified by:
      asInputStream in interface PositionedStream
      Returns:
      An InputStream reference to self.

    • getPosition

      public long getPosition()
      Returns the current byte position.
      Specified by:
      getPosition in interface PositionedStream
      Returns:
      The current byte position.

    • reposition

      public void reposition(long requestedPos) throws IOException
      Repositions the stream to the requested byte position.
      Specified by:
      reposition in interface PositionedStream
      Parameters:
      requestedPos - the requested position, starting at 0
      Throws:
      EOFException - if the requested position is larger than the length
      IOException - if obtaining the stream length fails