public
class
CipherInputStream
extends FilterInputStream
java.lang.Object | |||
↳ | java.io.InputStream | ||
↳ | java.io.FilterInputStream | ||
↳ | javax.crypto.CipherInputStream |
A CipherInputStream is composed of an InputStream and a Cipher so that read() methods return data that are read in from the underlying InputStream but have been additionally processed by the Cipher. The Cipher must be fully initialized before being used by a CipherInputStream.
For example, if the Cipher is initialized for decryption, the CipherInputStream will attempt to read in data and decrypt them, before returning the decrypted data.
This class adheres strictly to the semantics, especially the
failure semantics, of its ancestor classes
java.io.FilterInputStream and java.io.InputStream. This class has
exactly those methods specified in its ancestor classes, and
overrides them all. Moreover, this class catches all exceptions
that are not thrown by its ancestor classes. In particular, the
skip
method skips, and the available
method counts only data that have been processed by the encapsulated Cipher.
It is crucial for a programmer using this class not to use methods that are not defined or overriden in this class (such as a new method or constructor that is later added to one of the super classes), because the design and implementation of those methods are unlikely to have considered security impact with regard to CipherInputStream.
Inherited fields |
---|
From
class
java.io.FilterInputStream
|
Public constructors | |
---|---|
CipherInputStream(InputStream is, Cipher c)
Constructs a CipherInputStream from an InputStream and a Cipher. |
Protected constructors | |
---|---|
CipherInputStream(InputStream is)
Constructs a CipherInputStream from an InputStream without specifying a Cipher. |
Public methods | |
---|---|
int
|
available()
Returns the number of bytes that can be read from this input stream without blocking. |
void
|
close()
Closes this input stream and releases any system resources associated with the stream. |
boolean
|
markSupported()
Tests if this input stream supports the |
int
|
read()
Reads the next byte of data from this input stream. |
int
|
read(byte[] b, int off, int len)
Reads up to |
int
|
read(byte[] b)
Reads up to |
long
|
skip(long n)
Skips |
Inherited methods | |
---|---|
From
class
java.io.FilterInputStream
| |
From
class
java.io.InputStream
| |
From
class
java.lang.Object
| |
From
interface
java.io.Closeable
| |
From
interface
java.lang.AutoCloseable
|
CipherInputStream (InputStream is, Cipher c)
Constructs a CipherInputStream from an InputStream and a
Cipher.
Note: if the specified input stream or cipher is
null, a NullPointerException may be thrown later when
they are used.
Parameters | |
---|---|
is |
InputStream :
the to-be-processed input stream |
c |
Cipher :
an initialized Cipher object
|
CipherInputStream (InputStream is)
Constructs a CipherInputStream from an InputStream without
specifying a Cipher. This has the effect of constructing a
CipherInputStream using a NullCipher.
Note: if the specified input stream is null, a
NullPointerException may be thrown later when it is used.
Parameters | |
---|---|
is |
InputStream :
the to-be-processed input stream
|
int available ()
Returns the number of bytes that can be read from this input
stream without blocking. The available
method of
InputStream
returns 0
. This method
should be overridden by subclasses.
Returns | |
---|---|
int |
the number of bytes that can be read from this input stream without blocking. |
Throws | |
---|---|
IOException |
if an I/O error occurs. |
void close ()
Closes this input stream and releases any system resources associated with the stream.
The close
method of CipherInputStream
calls the close
method of its underlying input
stream.
Throws | |
---|---|
IOException |
if an I/O error occurs. |
boolean markSupported ()
Tests if this input stream supports the mark
and reset
methods, which it does not.
Returns | |
---|---|
boolean |
false , since this class does not support the
mark and reset methods. |
int read ()
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.
Returns | |
---|---|
int |
the next byte of data, or -1 if the end of the
stream is reached. |
Throws | |
---|---|
IOException |
if an I/O error occurs. |
int read (byte[] b, int off, int len)
Reads up to len
bytes of data from this input stream
into an array of bytes. This method blocks until some input is
available. If the first argument is null,
up to
len
bytes are read and discarded.
Parameters | |
---|---|
b |
byte :
the buffer into which the data is read. |
off |
int :
the start offset in the destination array
buf |
len |
int :
the maximum number of bytes read. |
Returns | |
---|---|
int |
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:
int read (byte[] b)
Reads up to b.length
bytes of data from this input
stream into an array of bytes.
The read
method of InputStream
calls
the read
method of three arguments with the arguments
b
, 0
, and b.length
.
Parameters | |
---|---|
b |
byte :
the buffer into which the data is read. |
Returns | |
---|---|
int |
the total number of bytes read into the buffer, or
-1 is there is no more data because the end of
the stream has been reached. |
Throws | |
---|---|
IOException |
if an I/O error occurs. |
See also:
long skip (long n)
Skips n
bytes of input from the bytes that can be read
from this input stream without blocking.
Fewer bytes than requested might be skipped.
The actual number of bytes skipped is equal to n
or
the result of a call to
,
whichever is smaller.
If available
n
is less than zero, no bytes are skipped.
The actual number of bytes skipped is returned.
Parameters | |
---|---|
n |
long :
the number of bytes to be skipped. |
Returns | |
---|---|
long |
the actual number of bytes skipped. |
Throws | |
---|---|
IOException |
if an I/O error occurs. |