javax.crypto
Class CipherInputStream

java.lang.Object
  java.io.InputStream
      java.io.FilterInputStream
          javax.crypto.CipherInputStream

All Implemented Interfaces:

Closeable

public class CipherInputStream
extends FilterInputStream

This class wraps an InputStream and a cipher so that read() methods return data that are read from the underlying InputStream and processed by the cipher.

The cipher must be initialized for the requested operation before being used by a CipherInputStream. For example, if a cipher initialized for decryption is used with a CipherInputStream, the CipherInputStream tries to read the data an decrypt them before returning.

Since:

Android 1.0

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

protected	CipherInputStream(InputStream is) Creates a new CipherInputStream instance for an InputStream without a cipher.
	CipherInputStream(InputStream is, Cipher c) Creates a new CipherInputStream instance for an InputStream and a cipher.

Method Summary

int	available() Returns the number of bytes available without blocking.
void	close() Closes this CipherInputStream, also closes the underlying input stream and call doFinal on the cipher object.
boolean	markSupported() Returns whether this input stream supports mark and reset , which it does not.
int	read() Reads the next byte from this cipher input stream.
int	read(byte[] b) Reads the next b.length bytes from this input stream into buffer b.
int	read(byte[] b, int off, int len) Reads the next len bytes from this input stream into buffer b starting at offset off.
long	skip(long n) Skips up to n bytes from this input stream.

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

CipherInputStream

public CipherInputStream(InputStream is,
                         Cipher c)

Creates a new CipherInputStream instance for an InputStream and a cipher.

Parameters:

is - the input stream to read data from.

c - the cipher to process the data with.

Since:

Android 1.0

CipherInputStream

protected CipherInputStream(InputStream is)

Creates a new CipherInputStream instance for an InputStream without a cipher.

A NullCipher is created and used to process the data.

Parameters:

is - the input stream to read data from.

Since:

Android 1.0

Method Detail

read

public int read()
         throws IOException

Reads the next byte from this cipher input stream.

Overrides:

read in class FilterInputStream

Returns:

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

Throws:

IOException - if an error occurs.

Since:

Android 1.0

read

public int read(byte[] b)
         throws IOException

Reads the next b.length bytes from this input stream into buffer b.

Overrides:

read in class FilterInputStream

Parameters:

b - the buffer to be filled with data.

Returns:

the number of bytes filled into buffer b, or -1 if the end of the stream is reached.

Throws:

IOException - if an error occurs.

Since:

Android 1.0

read

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

Reads the next len bytes from this input stream into buffer b starting at offset off.

if b is null, the next len bytes are read and discarded.

Overrides:

read in class FilterInputStream

Parameters:

b - the buffer to be filled with data.

off - the offset to start in the buffer.

len - the maximum number of bytes to read.

Returns:

the number of bytes filled into buffer b, or -1 of the of the stream is reached.

Throws:

IOException - if an error occurs.

NullPointerException - if the underlying input stream is null.

Since:

Android 1.0

skip

public long skip(long n)
          throws IOException

Skips up to n bytes from this input stream.

The number of bytes skipped depends on the result of a call to available. The smaller of n and the result are the number of bytes being skipped.

Skipping is (currently) not supported in Android.

Overrides:

skip in class FilterInputStream

Parameters:

n - the number of bytes that should be skipped.

Returns:

the number of bytes actually skipped.

Throws:

IOException - if an error occurs

Since:

Android 1.0

See Also:

FilterInputStream.mark(int), FilterInputStream.reset()

available

public int available()
              throws IOException

Returns the number of bytes available without blocking. It (currently) always returns 0 in Android.

Overrides:

available in class FilterInputStream

Returns:

the number of bytes available, currently zero.

Throws:

IOException - if an error occurs

Since:

Android 1.0

close

public void close()
           throws IOException

Closes this CipherInputStream, also closes the underlying input stream and call doFinal on the cipher object.

Specified by:

close in interface Closeable

Overrides:

close in class FilterInputStream

Throws:

IOException - if an error occurs.

Since:

Android 1.0

markSupported

public boolean markSupported()

Returns whether this input stream supports mark and reset , which it does not.

Overrides:

markSupported in class FilterInputStream

Returns:

false, since this input stream does not support mark and reset.

Since:

Android 1.0

See Also:

FilterInputStream.mark(int), FilterInputStream.reset(), FilterInputStream.skip(long)