com.kitfox.svg.xml.cpx
Class CPXInputStream

java.lang.Object
  java.io.InputStream
      java.io.FilterInputStream
          com.kitfox.svg.xml.cpx.CPXInputStream

All Implemented Interfaces:

CPXConsts, Closeable

public class CPXInputStream
extends FilterInputStream
implements CPXConsts

This class reads/decodes the CPX file format. This format is a simple compression/encryption transformer for XML data. This stream takes in encrypted XML and outputs decrypted. It does this by checking for a magic number at the start of the stream. If absent, it treats the stream as raw XML data and passes it through unaltered. This is to aid development in debugging versions, where the XML files will not be in CPX format. See http://java.sun.com/developer/technicalArticles/Security/Crypto/

Author:

Mark McKay, Mark McKay

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Fields inherited from interface com.kitfox.svg.xml.cpx.CPXConsts

MAGIC_NUMBER, XL_PLAIN, XL_ZIP_CRYPT

Constructor Summary

CPXInputStream(InputStream in)
Creates a new instance of CPXInputStream

Method Summary

int	available() This method returns 1 if we've not reached EOF, 0 if we have.
void	close() Closes this input stream and releases any system resources associated with the stream.
protected boolean	decryptChunk() Call when inflater indicates that it needs more bytes.
boolean	markSupported() We do not allow marking
int	read() Reads the next byte of data from this input stream.
int	read(byte[] b) Reads up to byte.length bytes of data from this input stream into an array of bytes.
int	read(byte[] b, int off, int len) Reads up to len bytes of data from this input stream into an array of bytes.
long	skip(long n) Skips bytes by reading them into a cached buffer

Methods inherited from class java.io.FilterInputStream

mark, reset

Methods inherited from class java.lang.Object

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

Constructor Detail

CPXInputStream

public CPXInputStream(InputStream in)
               throws IOException

Creates a new instance of CPXInputStream

Throws:

IOException

Method Detail

markSupported

public boolean markSupported()

We do not allow marking

Overrides:

markSupported in class FilterInputStream

close

public void close()
           throws IOException

Closes this input stream and releases any system resources associated with the stream. This method simply performs in.close().

Specified by:

close in interface Closeable

Overrides:

close in class FilterInputStream

Throws:

IOException - if an I/O error occurs.

See Also:

FilterInputStream.in

read

public int read()
         throws IOException

Reads the next byte of data from this input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

This method simply performs in.read() and returns the result.

Overrides:

read in class FilterInputStream

Returns:

the next byte of data, or -1 if the end of the stream is reached.

Throws:

IOException - if an I/O error occurs.

See Also:

FilterInputStream.in

read

public int read(byte[] b)
         throws IOException

Reads up to byte.length bytes of data from this input stream into an array of bytes. This method blocks until some input is available.

This method simply performs the call read(b, 0, b.length) and returns the result. It is important that it does not do in.read(b) instead; certain subclasses of FilterInputStream depend on the implementation strategy actually used.

Overrides:

read in class FilterInputStream

Parameters:

b - the buffer into which the data is read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

IOException - if an I/O error occurs.

See Also:

FilterInputStream.read(byte[], int, int)

read

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

Reads up to len bytes of data from this input stream into an array of bytes. This method blocks until some input is available.

This method simply performs in.read(b, off, len) and returns the result.

Overrides:

read in class FilterInputStream

Parameters:

b - the buffer into which the data is read.

off - the start offset of the data.

len - the maximum number of bytes read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

IOException - if an I/O error occurs.

See Also:

FilterInputStream.in

decryptChunk

protected boolean decryptChunk()
                        throws IOException

Call when inflater indicates that it needs more bytes.

Returns:

- true if we decrypted more bytes to deflate, false if we encountered the end of stream

Throws:

IOException

available

public int available()

This method returns 1 if we've not reached EOF, 0 if we have. Programs should not rely on this to determine the number of bytes that can be read without blocking.

Overrides:

available in class FilterInputStream

skip

public long skip(long n)
          throws IOException

Skips bytes by reading them into a cached buffer

Overrides:

skip in class FilterInputStream

Throws:

IOException