org.apache.derby.iapi.types
Class ReaderToUTF8Stream

java.lang.Object
  java.io.InputStream
      org.apache.derby.iapi.types.ReaderToUTF8Stream

All Implemented Interfaces:

java.io.Closeable

public final class ReaderToUTF8Stream
extends java.io.InputStream

Converts a java.io.Reader to the on-disk UTF8 format used by Derby for character types.

Field Summary

private int	blen
private int	boff
private byte[]	buffer
private static int	BUFSIZE
private int	charsToTruncate Number of characters to truncate from this stream The SQL standard allows for truncation of trailing spaces for clobs,varchar,char.
private boolean	eof
private int	maximumLength The maximum allowed length of the stream.
private boolean	multipleBuffer
private LimitReader	reader Application's reader wrapped in a LimitReader.
private static char	SPACE
private java.lang.String	typeName The type name for the column data is inserted into.
private int	valueLength Length of the final value, after truncation if any, in characters.

Constructor Summary

ReaderToUTF8Stream(java.io.Reader appReader, int valueLength, int numCharsToTruncate, java.lang.String typeName)
Create a stream that will truncate trailing blanks if required/allowed.

ReaderToUTF8Stream(java.io.Reader appReader, int maximumLength, java.lang.String typeName)
Create a UTF-8 stream for a length less application reader.

Method Summary

int	available() Return an optimized version of bytes available to read from the stream Note, it is not exactly per java.io.InputStream#available()
private boolean	canTruncate() Determine if trailing blank truncation is allowed.
private void	checkSufficientData() Validate the length of the stream, take corrective action if allowed.
void	close() return resources
private void	fillBuffer(int startingOffset)
int	read() read from stream; characters converted to utf-8 derby specific encoding.
int	read(byte[] b, int off, int len)
private void	truncate() Attempt to truncate the stream by removing trailing blanks.

Methods inherited from class java.io.InputStream

mark, markSupported, read, reset, skip

Methods inherited from class java.lang.Object

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

Field Detail

reader

private LimitReader reader

Application's reader wrapped in a LimitReader.

buffer

private byte[] buffer

boff

private int boff

blen

private int blen

eof

private boolean eof

multipleBuffer

private boolean multipleBuffer

BUFSIZE

private static final int BUFSIZE

See Also:

Constant Field Values

charsToTruncate

private final int charsToTruncate

Number of characters to truncate from this stream The SQL standard allows for truncation of trailing spaces for clobs,varchar,char. If zero, no characters are truncated.

SPACE

private static final char SPACE

See Also:

Constant Field Values

valueLength

private final int valueLength

Length of the final value, after truncation if any, in characters. this stream needs to fit into a column of colWidth if truncation error happens ,then the error message includes information about the column width.

maximumLength

private final int maximumLength

The maximum allowed length of the stream.

typeName

private final java.lang.String typeName

The type name for the column data is inserted into.

Constructor Detail

ReaderToUTF8Stream

public ReaderToUTF8Stream(java.io.Reader appReader,
                          int valueLength,
                          int numCharsToTruncate,
                          java.lang.String typeName)

Create a stream that will truncate trailing blanks if required/allowed. If the stream must be truncated, the number of blanks to truncate is specified to allow the stream to be checked for exact length, as required by JDBC 3.0. If the stream is shorter or longer than specified, an exception is thrown during read.

Parameters:

appReader - application reader

valueLength - the length of the reader in characters

numCharsToTruncate - the number of trailing blanks to truncate

typeName - type name of the column data is inserted into

ReaderToUTF8Stream

public ReaderToUTF8Stream(java.io.Reader appReader,
                          int maximumLength,
                          java.lang.String typeName)

Create a UTF-8 stream for a length less application reader. A limit is placed on the length of the reader. If the reader exceeds the maximum length, truncation of trailing blanks is attempted. If truncation fails, an exception is thrown.

Parameters:

appReader - application reader

maximumLength - maximum allowed length in number of characters for the reader

typeName - type name of the column data is inserted into

Throws:

java.lang.IllegalArgumentException - if maximum length is negative, or type name is null

Method Detail

read

public int read()
         throws java.io.IOException

read from stream; characters converted to utf-8 derby specific encoding. If stream has been read, and eof reached, in that case any subsequent read will throw an EOFException

Specified by:

read in class java.io.InputStream

Throws:

java.io.IOException

See Also:

InputStream.read()

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

fillBuffer

private void fillBuffer(int startingOffset)
                 throws java.io.IOException

Throws:

java.io.IOException

checkSufficientData

private void checkSufficientData()
                          throws java.io.IOException

Validate the length of the stream, take corrective action if allowed. JDBC 3.0 (from tutorial book) requires that an input stream has the correct number of bytes in the stream. If the stream is too long, trailing blank truncation is attempted if allowed. If truncation fails, or is disallowed, an exception is thrown.

Throws:

java.io.IOException - if an errors occurs in the application stream

DerbyIOException - if Derby finds a problem with the stream; stream is too long and cannot be truncated, or the stream length does not match the specified length

canTruncate

private boolean canTruncate()

Determine if trailing blank truncation is allowed.

truncate

private void truncate()
               throws java.io.IOException

Attempt to truncate the stream by removing trailing blanks.

Throws:

java.io.IOException

close

public void close()
           throws java.io.IOException

return resources

Specified by:

close in interface java.io.Closeable

Overrides:

close in class java.io.InputStream

Throws:

java.io.IOException

available

public final int available()

Return an optimized version of bytes available to read from the stream Note, it is not exactly per java.io.InputStream#available()

Overrides:

available in class java.io.InputStream