com.jkristian.io
Class Base64DecodeOutputStream

java.lang.Object
  java.io.OutputStream
      java.io.FilterOutputStream
          com.jkristian.io.Base64DecodeOutputStream

All Implemented Interfaces:

java.io.Closeable, java.io.Flushable

public class Base64DecodeOutputStream
extends java.io.FilterOutputStream

A filter that decodes output from base64 encoding to binary bytes. Unexpected bytes are silently ignored.

Base64 encoding is defined by RFC 2045 (MIME) section 6.8.

Field Summary

protected boolean	flushCausesReset whether flush() resets the decoder
protected static byte[]	map
protected byte	n index of the next expected input sextet
protected static byte	NUL
protected static byte	PAD
protected byte	x the previous input sextet

Fields inherited from class java.io.FilterOutputStream

out

Constructor Summary

Base64DecodeOutputStream(java.io.OutputStream out)

Method Summary

void	flush()
static void	main(java.lang.String[] args) A unit test.
void	setFlushCausesReset(boolean b) Subsequently, a call to flush() will reset this object's state if and only if the given parameter is true.
void	write(byte[] b, int off, int len)
void	write(int b)

Methods inherited from class java.io.FilterOutputStream

close, write

Methods inherited from class java.lang.Object

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

Field Detail

n

protected byte n

index of the next expected input sextet

x

protected byte x

the previous input sextet

flushCausesReset

protected boolean flushCausesReset

whether flush() resets the decoder

PAD

protected static final byte PAD

See Also:

Constant Field Values

NUL

protected static final byte NUL

See Also:

Constant Field Values

map

protected static final byte[] map

Constructor Detail

Base64DecodeOutputStream

public Base64DecodeOutputStream(java.io.OutputStream out)

Parameters:

out - should be buffered (e.g. a BufferedOutputStream) for best performance. This class will write to it one byte at a time.

Method Detail

write

public void write(int b)
           throws java.io.IOException

Overrides:

write in class java.io.FilterOutputStream

Throws:

java.io.IOException

write

public void write(byte[] b,
                  int off,
                  int len)
           throws java.io.IOException

Overrides:

write in class java.io.FilterOutputStream

Throws:

java.io.IOException

flush

public void flush()
           throws java.io.IOException

Specified by:

flush in interface java.io.Flushable

Overrides:

flush in class java.io.FilterOutputStream

Throws:

java.io.IOException

setFlushCausesReset

public void setFlushCausesReset(boolean b)

Subsequently, a call to flush() will reset this object's state if and only if the given parameter is true. The default setting (if this method is not called) is false.

For example, write("BA"); flush(); write("BA") will ordinarily produce the same sequence of decoded bytes as write("BABA"); that is {4, 0, 64}. But {4, 4} will be produced if setFlushCausesReset(true) is called before flush(). In the latter case, the second "BA" will be decoded as if it appeared at the beginning of a stream.

Parameters:

b - whether the decoder will be reset by a subsequent call to flush(). false (the default) is appropriate if flush() is called merely for performance optimization, and should not affect decoding. true is appropriate if a call to flush() indicates a significant boundary in the data stream, such that previous bytes should not be combined with subsequent bytes for decoding.

main

public static void main(java.lang.String[] args)
                 throws java.io.IOException

A unit test. Output each parameter, decode it from base64 and re-encode it. If the re-encoded string differs from the input parameter, output the decoded byte string to System.err in hexadecimal.

Throws:

java.io.IOException