Class javax.crypto.CipherInputStream
java.lang.Object
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+----java.io.InputStream
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+----java.io.FilterInputStream
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+----javax.crypto.CipherInputStream
- public class CipherInputStream
- extends java.io.FilterInputStream
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(long)
method skips only data that have been
processed by the 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.
- Since:
- JCE1.2
- See Also:
- java.io.InputStream, java.io.FilterInputStream, Cipher, CipherOutputStream
Fields inherited from class java.io.FilterInputStream
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in |
Constructor Summary
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CipherInputStream(java.io.InputStream is,
Cipher c)
Constructs a CipherInputStream from an InputStream and a
Cipher.
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CipherInputStream(java.io.InputStream is)
Constructs a CipherInputStream from an InputStream without
specifying a Cipher.
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Method Summary
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int
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available()
Returns the number of bytes that can be read from this input
stream without blocking.
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void
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close()
Closes this input stream and releases any system resources
associated with the stream.
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boolean
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markSupported()
Tests if this input stream supports the mark
and reset methods, which it does not.
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int
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read()
Reads the next byte of data from this input stream.
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int
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read(byte[] b)
Reads up to b.length bytes of data from this input
stream into an array of bytes.
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int
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read(byte[] b,
int off,
int len)
Reads up to len bytes of data from this input stream
into an array of bytes.
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long
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skip(long n)
Skips over and discards n bytes of data from this
input stream.
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Methods inherited from class java.io.FilterInputStream
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available, close, mark, markSupported, read, read, read, reset, skip |
Methods inherited from class java.io.InputStream
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available, close, mark, markSupported, read, read, read, reset, skip |
Methods inherited from class java.lang.Object
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
CipherInputStream
public CipherInputStream(java.io.InputStream is,
Cipher c)
- Constructs a CipherInputStream from an InputStream and a
Cipher.
CipherInputStream
protected CipherInputStream(java.io.InputStream is)
- Constructs a CipherInputStream from an InputStream without
specifying a Cipher. This has the effect of constructing a
CipherInputStream using a NullCipher.
read
public int read() throws java.io.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.
- Returns:
- the next byte of data, or
-1
if the end of the
stream is reached. - Throws:
- java.io.IOException - if an I/O error occurs.
- Overrides:
- read in class java.io.FilterInputStream
read
public int read(byte[] b) throws java.io.IOException
- 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
- the buffer into which the data is read.
- Returns:
- 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:
- java.io.IOException - if an I/O error occurs.
- Overrides:
- read in class java.io.FilterInputStream
- See Also:
- read(byte[], int, int)
read
public int read(byte[] b,
int off,
int len) throws java.io.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. If the first argument is null,
up to
len
bytes are read and discarded.
- 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:
- java.io.IOException - if an I/O error occurs.
- Overrides:
- read in class java.io.FilterInputStream
- See Also:
- read()
skip
public long skip(long n) throws java.io.IOException
- Skips over and discards
n
bytes of data from this
input stream. The skip
method may, for a variety of
reasons, end up skipping over some smaller number of bytes,
possibly 0
. The actual number of bytes skipped is
returned.
- Parameters:
n
- the number of bytes to be skipped.
- Returns:
- the actual number of bytes skipped.
- Throws:
- java.io.IOException - if an I/O error occurs.
- Overrides:
- skip in class java.io.FilterInputStream
available
public int available() throws java.io.IOException
- 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:
- the number of bytes that can be read from this input stream
without blocking.
- Throws:
- java.io.IOException - if an I/O error occurs.
- Overrides:
- available in class java.io.FilterInputStream
close
public void close() throws java.io.IOException
- 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:
- java.io.IOException - if an I/O error occurs.
- Overrides:
- close in class java.io.FilterInputStream
markSupported
public boolean markSupported()
- Tests if this input stream supports the
mark
and reset
methods, which it does not.
- Returns:
false
, since this class does not support the
mark
and reset
methods.- Overrides:
- markSupported in class java.io.FilterInputStream
- See Also:
- mark(int), reset()