Package org.apache.derby.client.am

Class BlobLocatorInputStream

  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable
    class BlobLocatorInputStream
extends java.io.InputStream
    An InputStream that will use an locator to fetch the Blob value from the server.

    Closing a ByteArrayInputStream has no effect. The methods in this class can be called after the stream has been closed without generating an IOException.

    This InputStream implementation is pretty basic. No buffering of data is done. Hence, for efficiency #read(byte[]) should be used instead of #read(). Marks are not supported, but it should be pretty simple to extend the implementation to support this. A more efficient skip implementation should also be straight-forward.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private ClientBlob blob
      The Blob to be accessed.
      private ClientConnection connection
      Connection used to read Blob from server.
      private long currentPos
      Current position in the underlying Blob.
      private long maxPos
      Position in Blob where to stop reading.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      int read()  
      int read​(byte[] b, int off, int len)  
      private byte[] readBytes​(int len)
      Read the next len bytes of the Blob value from the server.

      • Methods inherited from class java.io.InputStream

        available, close, mark, markSupported, nullInputStream, read, readAllBytes, readNBytes, readNBytes, reset, skip, transferTo

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • connection

        private final ClientConnection connection
        Connection used to read Blob from server.

      • blob

        private final ClientBlob blob
        The Blob to be accessed.

      • currentPos

        private long currentPos
        Current position in the underlying Blob. Blobs are indexed from 1

      • maxPos

        private final long maxPos
        Position in Blob where to stop reading. maxPos starts counting from 1.

    • Constructor Detail

      • BlobLocatorInputStream

        BlobLocatorInputStream​(ClientConnection connection,
                       ClientBlob blob)
                throws SqlException
        Create an InputStream for reading the Blob value represented by the given locator based Blob object.
        Parameters:
        connection - connection to be used to read the Blob value from the server
        blob - Blob object that contains locator for the Blob value on the server.
        Throws:
        SqlException - if an error occurs when obtaining the length of the Blob.

      • BlobLocatorInputStream

        BlobLocatorInputStream​(ClientConnection connection,
                       ClientBlob blob,
                       long position,
                       long length)
                throws SqlException
        Create an InputStream for reading the Blob value represented by the given locator based Blob object.
        Parameters:
        connection - connection to be used to read the Blob value from the server
        blob - Blob object that contains locator for the Blob value on the server.
        position - the position in the Blob of the first byte to read.
        length - the maximum number of bytes to read from the Blob.
        Throws:
        SqlException - if an error occurs when obtaining the length of the Blob.

    • Method Detail

      • read

        public int read()
         throws java.io.IOException
        Specified by:
        read in class java.io.InputStream
        Throws:
        java.io.IOException
        See Also:
        This method fetches one byte at a time from the server. For more efficient retrieval, use #read(byte[]).

      • read

        public int read​(byte[] b,
                int off,
                int len)
         throws java.io.IOException
        Overrides:
        read in class java.io.InputStream
        Throws:
        java.io.IOException
        See Also:
        InputStream.read(byte[], int, int)

      • readBytes

        private byte[] readBytes​(int len)
                  throws java.io.IOException
        Read the next len bytes of the Blob value from the server.
        Parameters:
        len - number of bytes to read
        Returns:
        byte[] containing the read bytes
        Throws:
        java.io.IOException - Wrapped SqlException if reading from server fails.