java.lang.Object | |||
↳ | javax.imageio.stream.ImageInputStreamImpl | ||
↳ | javax.imageio.stream.ImageOutputStreamImpl | ||
↳ | javax.imageio.stream.FileCacheImageOutputStream |
An implementation of ImageOutputStream
that writes its
output to a regular OutputStream
. A file is used to
cache data until it is flushed to the output stream.
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Inherited Fields | |||||||||||
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Public Constructors | |||||||||||
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Constructs a
FileCacheImageOutputStream that will write
to a given outputStream . |
Public Methods | |||||||||||
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Closes this
FileCacheImageOututStream . | |||||||||||
Discards the initial portion of the stream prior to the
indicated postion.
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Returns
true since this
ImageOutputStream caches data in order to allow
seeking backwards. | |||||||||||
Returns
true since this
ImageOutputStream maintains a file cache. | |||||||||||
Returns
false since this
ImageOutputStream does not maintain a main memory
cache. | |||||||||||
Returns
-1L to indicate that the stream has unknown
length. | |||||||||||
Reads a single byte from the stream and returns it as an
int between 0 and 255. | |||||||||||
Reads up to
len bytes from the stream, and stores
them into b starting at index off . | |||||||||||
Sets the current stream position and resets the bit offset to
0.
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Writes a sequence of bytes to the stream at the current
position.
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Writes a single byte to the stream at the current position.
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Constructs a FileCacheImageOutputStream
that will write
to a given outputStream
.
A temporary file is used as a cache. If
cacheDir
is non-null
and is a
directory, the file will be created there. If it is
null
, the system-dependent default temporary-file
directory will be used (see the documentation for
File.createTempFile
for details).
stream | an OutputStream to write to. |
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cacheDir | a File indicating where the
cache file should be created, or null to use the
system directory. |
IllegalArgumentException | if stream
is null . |
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IllegalArgumentException | if cacheDir is
non-null but is not a directory. |
IOException | if a cache file cannot be created. |
Closes this FileCacheImageOututStream
. All
pending data is flushed to the output, and the cache file
is closed and removed. The destination OutputStream
is not closed.
IOException | if an error occurs. |
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Discards the initial portion of the stream prior to the
indicated postion. Attempting to seek to an offset within the
flushed portion of the stream will result in an
IndexOutOfBoundsException
.
Calling flushBefore
may allow classes
implementing this interface to free up resources such as memory
or disk space that are being used to store data from the
stream.
pos | a long containing the length of the
stream prefix that may be flushed. |
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IOException |
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Returns true
since this
ImageOutputStream
caches data in order to allow
seeking backwards.
true
.Returns true
since this
ImageOutputStream
maintains a file cache.
true
.Returns false
since this
ImageOutputStream
does not maintain a main memory
cache.
false
.Returns -1L
to indicate that the stream has unknown
length. Subclasses must override this method to provide actual
length information.
Reads a single byte from the stream and returns it as an
int
between 0 and 255. If EOF is reached,
-1
is returned.
Subclasses must provide an implementation for this method. The subclass implementation should update the stream position before exiting.
The bit offset within the stream must be reset to zero before the read occurs.
-1
if EOF is reached.IOException |
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Reads up to len
bytes from the stream, and stores
them into b
starting at index off
.
If no bytes can be read because the end of the stream has been
reached, -1
is returned.
The bit offset within the stream must be reset to zero before the read occurs.
Subclasses must provide an implementation for this method. The subclass implementation should update the stream position before exiting.
b | an array of bytes to be written to. |
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off | the starting position within b to write to. |
len | the maximum number of bytes to read. |
-1
to indicate EOF.IOException |
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Sets the current stream position and resets the bit offset to
0. It is legal to seek past the end of the file; an
EOFException
will be thrown only if a read is
performed. The file length will not be increased until a write
is performed.
pos | a long containing the desired file
pointer position. |
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IndexOutOfBoundsException | if pos is smaller
than the flushed position. |
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IOException | if any other I/O error occurs. |
Writes a sequence of bytes to the stream at the current
position. If len
is 0, nothing is written.
The byte b[off]
is written first, then the byte
b[off + 1]
, and so on.
If the bit offset within the stream is non-zero, the
remainder of the current byte is padded with 0s
and written out first. The bit offset will be 0 after the
write. Implementers can use the
method of flushBits
to guarantee this.ImageOutputStreamImpl
b | an array of byte s to be written. |
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off | the start offset in the data. |
len | the number of byte s to write. |
IOException |
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Writes a single byte to the stream at the current position.
The 24 high-order bits of b
are ignored.
If the bit offset within the stream is non-zero, the
remainder of the current byte is padded with 0s
and written out first. The bit offset will be 0 after the
write. Implementers can use the
method of flushBits
to guarantee this.ImageOutputStreamImpl
b | an int whose lower 8 bits are to be
written. |
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IOException |
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