Apache Derby Client JDBC Driver 10.17.1.0 · org.apache.derby.client.am.ByteArrayCombinerStream

A stream whose source is a list of byte arrays. This class was created when first implementing the JDBC 4 length less overloads in the client driver. The reason was missing support for streaming data with unknown length from the client to the server. The purpose of the stream is to avoid having to repeatedly copy data to grow the byte buffer, or doing a single big copy to combine the byte arrays in the end. This is important for the temporary solution, since we must materialize the stream to find the length anyway. If there is less data available than the specified length, an exception is thrown. Available data is determined by the length of the byte arrays, not the contents of them. A byte array with all 0's is considered valid data. Besides from truncation, this stream does not change the underlying data in any way.

Field Summary

Modifier and Type	Field and Description
private int	arrayIndex Index of the array we are currently reading from.
private final ArrayList<byte[]>	arrays A list of the arrays to combine.
private byte[]	curArray The array we are currently reading from.
private long	gOffset Global offset into the whole stream.
private int	off The local offset into the current array.
private final long	specifiedLength Length of the stream.

Constructor Summary

Access	Constructor and Description
public	ByteArrayCombinerStream(ArrayList<byte[]> an `ArrayList` with references to the source byte arrays. The references are copied to a new `ArrayList` instance. arraysIn, long the length of the stream. Never published outside this object. Note that the length specified can be shorter than the actual number of bytes in the byte arrays. length) Create a stream whose source is a list of byte arrays.

Method Summary

Modifier and Type	Method and Description
public int	Returns: number of available bytes available() Overrides java.io.InputStream.available. Return the number of available bytes.
private byte[]	Returns: a `byte[]`-object, or `null` if there are no more arrays nextArray() Fetch the next array to read data from.
public int	Returns: a byte, or `-1` if the end-of-stream is reached read() Implements abstract java.io.InputStream.read. Read a single byte.
public int	Returns: the number of bytes read, or `-1` if end-of-stream is reached read(byte[] the array to copy bytes into buf, int offset into the array offset, int the maximum number of bytes to read length) Overrides java.io.InputStream.read. Reads up to len bytes of data from the input stream into an array of bytes.

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

Field Detail

arrayIndex	back to summary
private int arrayIndex Index of the array we are currently reading from.

arrays	back to summary
private final ArrayList<byte[]> arrays A list of the arrays to combine.

curArray	back to summary
private byte[] curArray The array we are currently reading from.

gOffset	back to summary
private long gOffset Global offset into the whole stream.

off	back to summary
private int off The local offset into the current array.

specifiedLength	back to summary
private final long specifiedLength Length of the stream.

Constructor Detail

ByteArrayCombinerStream back to summary

ByteArrayCombinerStream	back to summary
public ByteArrayCombinerStream(ArrayList<byte[]> arraysIn, long length) Create a stream whose source is a list of byte arrays. Parameters arraysIn:ArrayList<byte[]> an `ArrayList` with references to the source byte arrays. The references are copied to a new `ArrayList` instance. length:long the length of the stream. Never published outside this object. Note that the length specified can be shorter than the actual number of bytes in the byte arrays. Exceptions IllegalArgumentException: if there is less data available than specified by `length`, or `length` is negative.

public ByteArrayCombinerStream(ArrayList<byte[]> arraysIn, long length)

Create a stream whose source is a list of byte arrays.

Parameters

arraysIn:ArrayList<byte[]>: an ArrayList with references to the source byte arrays. The references are copied to a new ArrayList instance.
length:long: the length of the stream. Never published outside this object. Note that the length specified can be shorter than the actual number of bytes in the byte arrays.

Exceptions

IllegalArgumentException:: if there is less data available than specified by length, or length is negative.

Method Detail

available	back to summary
public int available() Overrides java.io.InputStream.available. Return the number of available bytes. The method assumes the specified length of the stream is correct. Returns:int number of available bytes

available

back to summary

public int available()

Overrides java.io.InputStream.available.

Return the number of available bytes. The method assumes the specified length of the stream is correct.

Returns:int: number of available bytes

nextArray back to summary

nextArray	back to summary
private byte[] nextArray() Fetch the next array to read data from. The reference in the `ArrayList` is cleared when the array is "taken out". Returns:byte[] a `byte[]`-object, or `null` if there are no more arrays

private byte[] nextArray()

Fetch the next array to read data from. The reference in the ArrayList is cleared when the array is "taken out".

Returns:byte[]: a byte[]-object, or null if there are no more arrays

read back to summary

read	back to summary
public int read() throws IOException Implements abstract java.io.InputStream.read. Read a single byte. Returns:int a byte, or `-1` if the end-of-stream is reached Exceptions IOException: Doc from java.io.InputStream.read. if an I/O error occurs.

public int read() throws IOException

Implements abstract java.io.InputStream.read.

Read a single byte.

Returns:int

a byte, or -1 if the end-of-stream is reached

Exceptions

IOException:

Doc from java.io.InputStream.read.

if an I/O error occurs.

read back to summary

read	back to summary
public int read(byte[] buf, int offset, int length) 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. Parameters buf:byte[] the array to copy bytes into offset:int offset into the array length:int the maximum number of bytes to read Returns:int the number of bytes read, or `-1` if end-of-stream is reached Exceptions IOException: Doc from java.io.InputStream.read. 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.

public int read(byte[] buf, int offset, int length) 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.

Parameters

buf:byte[]: the array to copy bytes into
offset:int: offset into the array
length:int: the maximum number of bytes to read

Returns:int

the number of bytes read, or -1 if end-of-stream is reached

Exceptions

IOException:

Doc from java.io.InputStream.read.

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.

public Class ByteArrayCombinerStream

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Field Detail

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