org.apache.derby.client.am

Class ByteArrayCombinerStream

java.lang.Object

java.io.InputStream

org.apache.derby.client.am.ByteArrayCombinerStream

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class ByteArrayCombinerStream
extends java.io.InputStream

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.

Constructor Summary

Constructors

Constructor and Description
ByteArrayCombinerStream(java.util.ArrayList<byte[]> arraysIn, long length) Create a stream whose source is a list of byte arrays.

Method Summary

Modifier and Type	Method and Description
int	available() Return the number of available bytes.
int	read() Read a single byte.
int	read(byte[] buf, int offset, int length) Reads up to len bytes of data from the input stream into an array of bytes.

Methods inherited from class java.io.InputStream

close, mark, markSupported, read, reset, skip

Methods inherited from class java.lang.Object

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

Constructor Detail

ByteArrayCombinerStream

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

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

Parameters:

arraysIn - an ArrayList with references to the source byte arrays. The references are copied to a new ArrayList instance.

length - 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.

Throws:

java.lang.IllegalArgumentException - if there is less data available than specified by length, or length is negative.

Method Detail

read

public int read()
         throws java.io.IOException

Read a single byte.

Specified by:

read in class java.io.InputStream

Returns:

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

Throws:

java.io.IOException

read

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

Overrides:

read in class java.io.InputStream

Parameters:

buf - the array to copy bytes into

offset - offset into the array

length - the maximum number of bytes to read

Returns:

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

Throws:

java.io.IOException

available

public int available()

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

Overrides:

available in class java.io.InputStream

Returns:

number of available bytes