public
class
CipherOutputStream
extends FilterOutputStream
| java.lang.Object | |||
| ↳ | java.io.OutputStream | ||
| ↳ | java.io.FilterOutputStream | ||
| ↳ | javax.crypto.CipherOutputStream | ||
A CipherOutputStream is composed of an OutputStream and a Cipher so that write() methods first process the data before writing them out to the underlying OutputStream. The cipher must be fully initialized before being used by a CipherOutputStream.
For example, if the cipher is initialized for encryption, the CipherOutputStream will attempt to encrypt data before writing out the encrypted data.
This class adheres strictly to the semantics, especially the failure semantics, of its ancestor classes java.io.OutputStream and java.io.FilterOutputStream. 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.
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 CipherOutputStream.
Inherited fields |
|---|
 From
class
java.io.FilterOutputStream
|
Public constructors | |
|---|---|
CipherOutputStream(OutputStream os, Cipher c)
Constructs a CipherOutputStream from an OutputStream and a Cipher. |
|
Protected constructors | |
|---|---|
CipherOutputStream(OutputStream os)
Constructs a CipherOutputStream from an OutputStream without specifying a Cipher. |
|
Public methods | |
|---|---|
void
|
close()
Closes this output stream and releases any system resources associated with this stream. |
void
|
flush()
Flushes this output stream by forcing any buffered output bytes that have already been processed by the encapsulated cipher object to be written out. |
void
|
write(byte[] b)
Writes |
void
|
write(byte[] b, int off, int len)
Writes |
void
|
write(int b)
Writes the specified byte to this output stream. |
Inherited methods | |
|---|---|
From
class
java.io.FilterOutputStream
| |
From
class
java.io.OutputStream
| |
From
class
java.lang.Object
| |
From
interface
java.io.Closeable
| |
From
interface
java.io.Flushable
| |
From
interface
java.lang.AutoCloseable
| |
CipherOutputStream (OutputStream os, Cipher c)
Constructs a CipherOutputStream from an OutputStream and a
Cipher.
Note: if the specified output stream or cipher is
null, a NullPointerException may be thrown later when
they are used.
| Parameters | |
|---|---|
os |
OutputStream:
the OutputStream object |
c |
Cipher:
an initialized Cipher object
|
CipherOutputStream (OutputStream os)
Constructs a CipherOutputStream from an OutputStream without
specifying a Cipher. This has the effect of constructing a
CipherOutputStream using a NullCipher.
Note: if the specified output stream is null, a
NullPointerException may be thrown later when it is used.
| Parameters | |
|---|---|
os |
OutputStream:
the OutputStream object
|
void close ()
Closes this output stream and releases any system resources associated with this stream.
This method invokes the doFinal method of the encapsulated
cipher object, which causes any bytes buffered by the encapsulated
cipher to be processed. The result is written out by calling the
flush method of this output stream.
This method resets the encapsulated cipher object to its initial state
and calls the close method of the underlying output
stream.
| Throws | |
|---|---|
IOException |
if an I/O error occurs. |
void flush ()
Flushes this output stream by forcing any buffered output bytes that have already been processed by the encapsulated cipher object to be written out.
Any bytes buffered by the encapsulated cipher
and waiting to be processed by it will not be written out. For example,
if the encapsulated cipher is a block cipher, and the total number of
bytes written using one of the write methods is less than
the cipher's block size, no bytes will be written out.
| Throws | |
|---|---|
IOException |
if an I/O error occurs. |
void write (byte[] b)
Writes b.length bytes from the specified byte array
to this output stream.
The write method of
CipherOutputStream calls the write
method of three arguments with the three arguments
b, 0, and b.length.
| Parameters | |
|---|---|
b |
byte:
the data. |
| Throws | |
|---|---|
NullPointerException |
if b is null. |
IOException |
if an I/O error occurs. |
See also:
Developers
void write (byte[] b,
int off,
int len)
Writes len bytes from the specified byte array
starting at offset off to this output stream.
| Parameters | |
|---|---|
b |
byte:
the data. |
off |
int:
the start offset in the data. |
len |
int:
the number of bytes to write. |
| Throws | |
|---|---|
IOException |
if an I/O error occurs. |
void write (int b)
Writes the specified byte to this output stream.
| Parameters | |
|---|---|
b |
int:
the byte. |
| Throws | |
|---|---|
IOException |
if an I/O error occurs. |