java.lang.Object | |||
↳ | java.io.InputStream | ||
↳ | java.io.FilterInputStream | ||
↳ | javax.crypto.CipherInputStream |
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.
[Expand]
Inherited Fields
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From class
java.io.FilterInputStream
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Public Constructors | |||||||||||
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Creates a new
CipherInputStream
instance for an
InputStream
and a cipher.
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Protected Constructors | |||||||||||
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Creates a new
CipherInputStream
instance for an
InputStream
without a cipher.
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Public Methods | |||||||||||
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Returns an estimated number of bytes that can be read or skipped without blocking for more
input.
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Closes this
CipherInputStream
, also closes the underlying input
stream and call
doFinal
on the cipher object.
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Returns whether this input stream supports
mark
and
reset
, which it does not.
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Reads the next byte from this cipher input stream.
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Reads the next
len
bytes from this input stream into buffer
buf
starting at offset
off
.
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Skips
byteCount
bytes in this stream.
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[Expand]
Inherited Methods
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From class
java.io.FilterInputStream
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From class
java.io.InputStream
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From class
java.lang.Object
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From interface
java.io.Closeable
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From interface
java.lang.AutoCloseable
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Creates a new
CipherInputStream
instance for an
InputStream
and a cipher.
Warning:
passing a null source creates an invalid
CipherInputStream
. All read operations on such a stream will
fail.
is | the input stream to read data from. |
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c | the cipher to process the data with. |
Creates a new
CipherInputStream
instance for an
InputStream
without a cipher.
A
NullCipher
is created and used to process the data.
is | the input stream to read data from. |
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Returns an estimated number of bytes that can be read or skipped without blocking for more input.
Note that this method provides such a weak guarantee that it is not very useful in practice.
Firstly, the guarantee is "without blocking for more input" rather than "without blocking": a read may still block waiting for I/O to complete — the guarantee is merely that it won't have to wait indefinitely for data to be written. The result of this method should not be used as a license to do I/O on a thread that shouldn't be blocked.
Secondly, the result is a conservative estimate and may be significantly smaller than the actual number of bytes available. In particular, an implementation that always returns 0 would be correct. In general, callers should only use this method if they'd be satisfied with treating the result as a boolean yes or no answer to the question "is there definitely data ready?".
Thirdly, the fact that a given number of bytes is "available" does not guarantee that a read or skip will actually read or skip that many bytes: they may read or skip fewer.
It is particularly important to realize that you
must not
use this method to
size a container and assume that you can read the entirety of the stream without needing
to resize the container. Such callers should probably write everything they read to a
ByteArrayOutputStream
and convert that to a byte array. Alternatively, if you're
reading from a file,
length()
returns the current length of the file (though
assuming the file's length can't change may be incorrect, reading a file is inherently
racy).
The default implementation of this method in
InputStream
always returns 0.
Subclasses should override this method if they are able to indicate the number of bytes
available.
IOException |
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Closes this
CipherInputStream
, also closes the underlying input
stream and call
doFinal
on the cipher object.
IOException | if an error occurs. |
---|
Returns whether this input stream supports
mark
and
reset
, which it does not.
mark
and
reset
.
Reads the next byte from this cipher input stream.
-1
if the end of the stream is reached.
IOException | if an error occurs. |
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Reads the next
len
bytes from this input stream into buffer
buf
starting at offset
off
.
if
buf
is
null
, the next
len
bytes are read and
discarded.
buf
, or
-1
of the of the stream is reached.
IOException | if an error occurs. |
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NullPointerException |
if the underlying input stream is
null
.
|
Skips
byteCount
bytes in this stream. Subsequent
calls to
read
will not return these bytes unless
reset
is
used. This implementation skips
byteCount
bytes in the
filtered stream.
IOException |
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