iaik.utils

Class Base64InputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

iaik.utils.Base64InputStream

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

Direct Known Subclasses:

ASN1InputStream

public class Base64InputStream
extends java.io.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[1024];
 int r;
 while ((r = base64is.read(data)) != -1) {
   System.out.print(new String(data));
 }
 

To increase the throughput, an application can consider using a BufferedInputStream under this stream.

Version:

File Revision 21

See Also:

Base64OutputStream

Field Summary

Fields

Modifier and Type	Field and Description
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

Constructors

Constructor and Description
Base64InputStream(java.io.InputStream in) Creates a new Base64InputStream to read data from the specified input stream.
Base64InputStream(java.io.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

Methods

Modifier and Type	Method and Description
boolean	markSupported() Returns false since mark/reset is not supported by this input stream.
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.
static void	setDefaultIgnoreInvalidCharacters(boolean ignoreInvalidCharacters) Sets the default behavior for invalid character handling.
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, 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

See Also:

Constant Field Values

IGNORE

protected static final int IGNORE

See Also:

Constant Field Values

NOTIFY

protected static final int NOTIFY

See Also:

Constant Field Values

Constructor Detail

Base64InputStream

public Base64InputStream(java.io.InputStream in)

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

Parameters:

in - the underlying input stream.

Base64InputStream

public Base64InputStream(java.io.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.

ignoreInvalidCharacters - false to throw a Base64Exception when invalid characters are encountered, true to ignore invlaid characters

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.

Parameters:

ignoreInvalidCharacters - false to throw a Base64Exception when invalid characters are encountered, true to ignore invlaid characters

read

public int read(byte[] b,
       int off,
       int len)
         throws java.io.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 java.io.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:

java.io.IOException - if an I/O error occurs.

Base64Exception - if there is an Base64 format error

notify

protected void notify(byte[] buffer)
               throws java.io.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:

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

read

public int read()
         throws java.io.IOException,
                Base64Exception

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

Overrides:

read in class java.io.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:

java.io.IOException - if an I/O error occurs

Base64Exception - if there is a Base64 format error

setDefaultIgnoreInvalidCharacters

public static void setDefaultIgnoreInvalidCharacters(boolean ignoreInvalidCharacters)

Sets the default behavior for invalid character handling. When changing the default setting by calling this method, from now on any newly created Base64InputStream will handle invalid characters according the new settings, unless explicitly specified when creating the new instance.

Parameters:

ignoreInvalidCharacters - false to throw a Base64Exception when invalid characters are encountered, true to ignore invalid characters

markSupported

public boolean markSupported()

Returns false since mark/reset is not supported by this input stream.

Overrides:

markSupported in class java.io.FilterInputStream

Returns:

false