iaik.utils
Class Base64InputStream

java.lang.Object
  |
  +--java.io.InputStream
        |
        +--java.io.FilterInputStream
              |
              +--iaik.utils.Base64InputStream

Direct Known Subclasses:

ASN1InputStream

public class Base64InputStream

extends FilterInputStream

This class represents a FilterOutputStream that decodes Base64 encoded data passing through it. For reading - and decoding - Base64 encoded data from the underlying input stream, use one of the read methods.

Base64 is the encoding format used by Multipurpose Internet Mail Extension (Mime) for transmitting non-text material over text-only communications channels. Base64 is based on a 65-character subset of US-ASCII, enabling 6 bits to be represented per printable character (see RFC 1521).

This class may be used for decoding Base64 encoding data read in from some file, e.g.:

 FileInputStream fis = new FileInputStream("test/base64.enc");
 Base64InputStream base64is = new Base64InputStream(fis);
 byte[] data = new byte[1000];
 int r;
 while ((r = base64is.read(data)) != -1) {
  System.out.print(new String(data));
 }
 

Version:

File Revision 18

See Also:

Base64OutputStream

Field Summary

protected int[]	decoding
protected static int	ERROR
protected static int	IGNORE
protected static int	NOTIFY

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

Base64InputStream(InputStream in)
Creates a new Base64InputStream to read data from the specified input stream.

Base64InputStream(InputStream in, boolean ignoreInvalidCharacters)
Creates a new Base64InputStream to read data from the specified input stream and specifies whether or not to ignore invalid BASE-64 characters.

Method Summary

protected void	notify(byte[] buffer) This method is called if a character specified with NOTIFY is encountered.
int	read() Returns the next BASE64 decoded byte, read from the underlying input stream.
int	read(byte[] b, int off, int len) Reads and decodes the specified number of data bytes from the underlying input stream into a byte array until bytes are available.
void	setIgnoreInvalidCharacters(boolean ignoreInvalidCharacters) Sets whether or not to ignore invalid BASE-64 characters in the input.

Methods inherited from class java.io.FilterInputStream

available, close, 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

decoding

protected int[] decoding

ERROR

protected static final int ERROR

IGNORE

protected static final int IGNORE

NOTIFY

protected static final int NOTIFY

Constructor Detail

Base64InputStream

public Base64InputStream(InputStream in)

Creates a new Base64InputStream to read data from the specified input stream.

Parameters:

in - the underlying input stream.

Base64InputStream

public Base64InputStream(InputStream in,
                         boolean ignoreInvalidCharacters)

Creates a new Base64InputStream to read data from the specified input stream and specifies whether or not to ignore invalid BASE-64 characters.

Parameters:

in - the underlying input stream.

Method Detail

setIgnoreInvalidCharacters

public void setIgnoreInvalidCharacters(boolean ignoreInvalidCharacters)

Sets whether or not to ignore invalid BASE-64 characters in the input. If set to false (the default) a Base64Exception will be thrown when such characters are encountered, otherwise they are just ignored.

read

public int read(byte[] b,
                int off,
                int len)
         throws IOException,
                Base64Exception

Reads and decodes the specified number of data bytes from the underlying input stream into a byte array until bytes are available.

The bytes are decoded and read to the given byte array, beginning at position off. The number of bytes read to the array are returned.

Overrides:

read in class FilterInputStream

Parameters:

b - the byte array into which the decoded bytes are read

off - the offset indicating the position in b to which the first decoded byte shall be read

len - the maximum number of bytes to be read

Returns:

the number of bytes read into the byte array, or -1 if no more bytes are available because the end of the stream already has been reached

Throws:

IOException - if an I/O error occurs.

Base64Exception - if there is an Base64 format error

notify

protected void notify(byte[] buffer)
               throws IOException

This method is called if a character specified with NOTIFY is encountered. This method does nothing and shall be overwritten by a sub-class.

Parameters:

buffer - the characters already read from the input stream; and the first one was marked with NOTIFY

Throws:

IOException - allows the subclass to throw an Exception if an error occurs

read

public int read()
         throws IOException,
                Base64Exception

Returns the next BASE64 decoded byte, read from the underlying input stream.

Overrides:

read in class FilterInputStream

Returns:

the next decoded byte, or -1 if no more byte is available because the end of the stream already has been reached

Throws:

IOException - if an I/O error occurs

Base64Exception - if there is a Base64 format error