Apache Derby Database Engine and Embedded JDBC Driver 10.17.1.0 · org.apache.derby.impl.jdbc.UpdatableBlobStream

Modifier and Type	Field and Description
private final EmbedBlob	blob
private boolean	materialized Flag to check if it is using stream from LOBStreamControl or from DVD.
private final long	maxPos Position in Blob where to stop reading unless EOF is reached first.
private long	pos
private InputStream	stream

Access	Constructor and Description
pack-priv	UpdatableBlobStream(EmbedBlob EmbedBlob this stream is associated with. blob, InputStream InputStream this class is going to use internally. is) Constructs UpdatableBlobStream using the the InputStream receives as the parameter.
pack-priv	UpdatableBlobStream(EmbedBlob EmbedBlob this stream is associated with. blob, InputStream InputStream this class is going to use internally. is, long initial position pos, long The length to which the underlying `InputStream` has to be restricted. len) Construct an `UpdatableBlobStream` using the `InputStream` received as parameter.

Method Summary

Modifier and Type	Method and Description
public int	Returns: the next byte of data, or `-1` if the end of the stream is reached. read() Implements abstract java.io.InputStream.read. Reads the next byte of data from the input stream.
public int	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. read(byte[] the buffer into which the data is read. b, int the start offset in array `b` at which the data is written. off, int the maximum number of bytes to read. len) Overrides java.io.InputStream.read. Reads up to `len` bytes of data from the input stream into an array of bytes.
public int	Returns: the total number of bytes read into the buffer, or `-1` is there is no more data because the end of the stream has been reached. read(byte[] the buffer into which the data is read. b) Overrides java.io.InputStream.read. Reads some number of bytes from the input stream and stores them into the buffer array `b`.
public long	Returns: the actual number of bytes skipped. skip(long the number of bytes to be skipped. n) Overrides java.io.InputStream.skip. Skips over and discards `n` bytes of data from this input stream.
private void	updateIfRequired() Checks if this object is using materialized blob if not it checks if the blob was materialized since this stream was last access.

Inherited from java.io.InputStream:: available close mark markSupported nullInputStream readAllBytes readNBytes readNBytes reset skipNBytes transferTo

Field Detail

blob	back to summary
private final EmbedBlob blob

materialized	back to summary
private boolean materialized Flag to check if it is using stream from LOBStreamControl or from DVD. `true` means data is read from LOBStreamControl, `false` means data is read from the DVD.

maxPos	back to summary
private final long maxPos Position in Blob where to stop reading unless EOF is reached first.

pos	back to summary
private long pos

stream	back to summary
private InputStream stream

Constructor Detail

UpdatableBlobStream back to summary

UpdatableBlobStream	back to summary
pack-priv UpdatableBlobStream(EmbedBlob blob, InputStream is) throws IOException Constructs UpdatableBlobStream using the the InputStream receives as the parameter. The initial position is set to the `0`. Parameters blob:EmbedBlob EmbedBlob this stream is associated with. is:InputStream InputStream this class is going to use internally. Exceptions IOException: if an I/O error occurs

pack-priv UpdatableBlobStream(EmbedBlob blob, InputStream is) throws IOException

Constructs UpdatableBlobStream using the the InputStream receives as the parameter. The initial position is set to the 0.

Parameters

blob:EmbedBlob: EmbedBlob this stream is associated with.
is:InputStream: InputStream this class is going to use internally.

Exceptions

IOException:: if an I/O error occurs

UpdatableBlobStream back to summary

UpdatableBlobStream	back to summary
pack-priv UpdatableBlobStream(EmbedBlob blob, InputStream is, long pos, long len) throws IOException Construct an `UpdatableBlobStream` using the `InputStream` received as parameter. The initial position in the stream is set to `pos` and the stream is restricted to a length of `len`. Parameters blob:EmbedBlob EmbedBlob this stream is associated with. is:InputStream InputStream this class is going to use internally. pos:long initial position len:long The length to which the underlying `InputStream` has to be restricted.

pack-priv UpdatableBlobStream(EmbedBlob blob, InputStream is, long pos, long len) throws IOException

Construct an UpdatableBlobStream using the InputStream received as parameter. The initial position in the stream is set to pos and the stream is restricted to a length of len.

Parameters

blob:EmbedBlob: EmbedBlob this stream is associated with.
is:InputStream: InputStream this class is going to use internally.
pos:long: initial position
len:long: The length to which the underlying InputStream has to be restricted.

Method Detail

read back to summary

read	back to summary
public int read() throws IOException Implements abstract java.io.InputStream.read. 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. Note that this stream will reflect changes made to the underlying Blob at positions equal to or larger then the current position. Returns:int the next byte of data, or `-1` if the end of the stream is reached. Exceptions IOException: if an I/O error occurs. See Also `InputStream#read`

public int read() throws IOException

Implements abstract java.io.InputStream.read.

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.

Note that this stream will reflect changes made to the underlying Blob at positions equal to or larger then the current position.

Returns:int

the next byte of data, or -1 if the end of the stream is reached.

Exceptions

IOException:: if an I/O error occurs.

See Also

InputStream#read

read back to summary

read	back to summary
public int read(byte[] b, int off, int len) throws IOException Overrides java.io.InputStream.read. 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. Note that this stream will reflect changes made to the underlying Blob at positions equal to or larger then the current position . Parameters b:byte[] the buffer into which the data is read. off:int the start offset in array `b` at which the data is written. len:int the maximum number of bytes to read. Returns:int 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. Exceptions IOException: If the first byte cannot be read for any reason other than end of file, or if the input stream has been closed, or if some other I/O error occurs. NullPointerException: If `b` is `null`. IndexOutOfBoundsException: If `off` is negative, `len` is negative, or `len` is greater than `b.length - off` See Also `java.io.InputStream#read(byte[], int, int)`

public int read(byte[] b, int off, int len) throws IOException

Overrides java.io.InputStream.read.

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.

Note that this stream will reflect changes made to the underlying Blob at positions equal to or larger then the current position .

Parameters

b:byte[]: the buffer into which the data is read.
off:int: the start offset in array b at which the data is written.
len:int: the maximum number of bytes to read.

Returns:int

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.

Exceptions

IOException:: If the first byte cannot be read for any reason other than end of file, or if the input stream has been closed, or if some other I/O error occurs.
NullPointerException:: If b is null.
IndexOutOfBoundsException:: If off is negative, len is negative, or len is greater than b.length - off

read back to summary

read	back to summary
public int read(byte[] b) throws IOException Overrides java.io.InputStream.read. Reads some number of bytes from the input stream and stores them into the buffer array `b`. 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. Note that this stream will reflect changes made to the underlying Blob at positions equal to or larger then the current position . Parameters b:byte[] the buffer into which the data is read. Returns:int the total number of bytes read into the buffer, or `-1` is there is no more data because the end of the stream has been reached. Exceptions IOException: If the first byte cannot be read for any reason other than the end of the file, if the input stream has been closed, or if some other I/O error occurs. NullPointerException: if `b` is `null`. See Also `java.io.InputStream#read(byte[])`

public int read(byte[] b) throws IOException

Overrides java.io.InputStream.read.

Reads some number of bytes from the input stream and stores them into the buffer array b. 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.

Note that this stream will reflect changes made to the underlying Blob at positions equal to or larger then the current position .

Parameters

b:byte[]: the buffer into which the data is read.

Returns:int

the total number of bytes read into the buffer, or -1 is there is no more data because the end of the stream has been reached.

Exceptions

IOException:: If the first byte cannot be read for any reason other than the end of the file, if the input stream has been closed, or if some other I/O error occurs.
NullPointerException:: if b is null.

See Also

java.io.InputStream#read(byte[])

skip back to summary

skip	back to summary
public long skip(long n) throws IOException Overrides java.io.InputStream.skip. Skips over and discards `n` bytes of data from this input stream. The `skip` method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly `0`. This may result from any of a number of conditions; reaching end of file before `n` bytes have been skipped is only one possibility. The actual number of bytes skipped is returned. If `n` is negative, no bytes are skipped. Note that this stream will reflect changes made to the underlying Blob at positions equal to or larger then the current position . Parameters n:long the number of bytes to be skipped. Returns:long the actual number of bytes skipped. Exceptions IOException: if the stream does not support seek, or if some other I/O error occurs. See Also `java.io.InputStream#skip(long)`

public long skip(long n) throws IOException

Overrides java.io.InputStream.skip.

Skips over and discards n bytes of data from this input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. This may result from any of a number of conditions; reaching end of file before n bytes have been skipped is only one possibility. The actual number of bytes skipped is returned. If n is negative, no bytes are skipped.

Note that this stream will reflect changes made to the underlying Blob at positions equal to or larger then the current position .

Parameters

n:long: the number of bytes to be skipped.

Returns:long

the actual number of bytes skipped.

Exceptions

IOException:: if the stream does not support seek, or if some other I/O error occurs.

See Also

java.io.InputStream#skip(long)

updateIfRequired	back to summary
private void updateIfRequired() throws IOException Checks if this object is using materialized blob if not it checks if the blob was materialized since this stream was last access. If the blob was materialized (due to one of the set methods) it gets the stream again and sets the position to current read position.

pack-priv Class UpdatableBlobStream

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