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Préférences
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JavaTM 2 Platform Std. Ed. v1.6.0
javax.imageio.stream
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Field Summary |
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Fields inherited from class javax.imageio.stream.ImageInputStreamImpl |
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bitOffset, byteOrder, flushedPos, streamPos |
Constructor Summary | |
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FileCacheImageOutputStream(OutputStream stream,
File cacheDir)
Constructs a FileCacheImageOutputStream that will write
to a given outputStream . |
Method Summary | |
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void |
close()
Closes this FileCacheImageOututStream . |
void |
flushBefore(long pos)
Discards the initial portion of the stream prior to the indicated postion. |
boolean |
isCached()
Returns true since this
ImageOutputStream caches data in order to allow
seeking backwards. |
boolean |
isCachedFile()
Returns true since this
ImageOutputStream maintains a file cache. |
boolean |
isCachedMemory()
Returns false since this
ImageOutputStream does not maintain a main memory
cache. |
long |
length()
Returns -1L to indicate that the stream has unknown
length. |
int |
read()
Reads a single byte from the stream and returns it as an int between 0 and 255. |
int |
read(byte[] b,
int off,
int len)
Reads up to len bytes from the stream, and stores
them into b starting at index off . |
void |
seek(long pos)
Sets the current stream position and resets the bit offset to 0. |
void |
write(byte[] b,
int off,
int len)
Writes a sequence of bytes to the stream at the current position. |
void |
write(int b)
Writes a single byte to the stream at the current position. |
Methods inherited from class javax.imageio.stream.ImageOutputStreamImpl |
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flushBits, write, writeBit, writeBits, writeBoolean, writeByte, writeBytes, writeChar, writeChars, writeChars, writeDouble, writeDoubles, writeFloat, writeFloats, writeInt, writeInts, writeLong, writeLongs, writeShort, writeShorts, writeUTF |
Methods inherited from class javax.imageio.stream.ImageInputStreamImpl |
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checkClosed, finalize, flush, getBitOffset, getByteOrder, getFlushedPosition, getStreamPosition, mark, read, readBit, readBits, readBoolean, readByte, readBytes, readChar, readDouble, readFloat, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedInt, readUnsignedShort, readUTF, reset, setBitOffset, setByteOrder, skipBytes, skipBytes |
Methods inherited from class java.lang.Object |
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clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Methods inherited from interface javax.imageio.stream.ImageInputStream |
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flush, getBitOffset, getByteOrder, getFlushedPosition, getStreamPosition, mark, read, readBit, readBits, readBoolean, readByte, readBytes, readChar, readDouble, readFloat, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedInt, readUnsignedShort, readUTF, reset, setBitOffset, setByteOrder, skipBytes, skipBytes |
Constructor Detail |
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public FileCacheImageOutputStream(OutputStream stream, File cacheDir) throws IOException
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.cacheDir
- a File
indicating where the
cache file should be created, or null
to use the
system directory.
IllegalArgumentException
- if stream
is null
.
IllegalArgumentException
- if cacheDir
is
non-null
but is not a directory.
IOException
- if a cache file cannot be created.Method Detail |
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public int read() throws IOException
ImageInputStreamImpl
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.
read
in interface ImageInputStream
read
in class ImageInputStreamImpl
-1
if EOF is reached.
IOException
- if the stream has been closed.public int read(byte[] b, int off, int len) throws IOException
ImageInputStreamImpl
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.
read
in interface ImageInputStream
read
in class ImageInputStreamImpl
b
- an array of bytes to be written to.off
- the starting position within b
to write to.len
- the maximum number of bytes to read.
-1
to indicate EOF.
IOException
- if an I/O error occurs.public void write(int b) throws IOException
ImageOutputStream
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
write
in interface DataOutput
write
in interface ImageOutputStream
write
in class ImageOutputStreamImpl
b
- an int
whose lower 8 bits are to be
written.
IOException
- if an I/O error occurs.public void write(byte[] b, int off, int len) throws IOException
ImageOutputStream
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
write
in interface DataOutput
write
in interface ImageOutputStream
write
in class ImageOutputStreamImpl
b
- an array of byte
s to be written.off
- the start offset in the data.len
- the number of byte
s to write.
IOException
- if an I/O error occurs.public long length()
ImageInputStreamImpl
-1L
to indicate that the stream has unknown
length. Subclasses must override this method to provide actual
length information.
length
in interface ImageInputStream
length
in class ImageInputStreamImpl
public void seek(long pos) throws IOException
EOFException
will be thrown only if a read is
performed. The file length will not be increased until a write
is performed.
seek
in interface ImageInputStream
seek
in class ImageInputStreamImpl
pos
- a long
containing the desired file
pointer position.
IndexOutOfBoundsException
- if pos
is smaller
than the flushed position.
IOException
- if any other I/O error occurs.public boolean isCached()
true
since this
ImageOutputStream
caches data in order to allow
seeking backwards.
isCached
in interface ImageInputStream
isCached
in class ImageInputStreamImpl
true
.isCachedMemory()
,
isCachedFile()
public boolean isCachedFile()
true
since this
ImageOutputStream
maintains a file cache.
isCachedFile
in interface ImageInputStream
isCachedFile
in class ImageInputStreamImpl
true
.isCached()
,
isCachedMemory()
public boolean isCachedMemory()
false
since this
ImageOutputStream
does not maintain a main memory
cache.
isCachedMemory
in interface ImageInputStream
isCachedMemory
in class ImageInputStreamImpl
false
.isCached()
,
isCachedFile()
public void close() throws IOException
FileCacheImageOututStream
. All
pending data is flushed to the output, and the cache file
is closed and removed. The destination OutputStream
is not closed.
close
in interface ImageInputStream
close
in class ImageInputStreamImpl
IOException
- if an error occurs.public void flushBefore(long pos) throws IOException
ImageInputStream
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.
flushBefore
in interface ImageInputStream
flushBefore
in interface ImageOutputStream
flushBefore
in class ImageInputStreamImpl
pos
- a long
containing the length of the
stream prefix that may be flushed.
IOException
- if an I/O error occurs.