public class FileCacheImageOutputStream extends ImageOutputStreamImpl
ImageOutputStream that writes its
output to a regular OutputStream. A file is used to
cache data until it is flushed to the output stream.bitOffset, byteOrder, flushedPos, streamPos| Constructor and Description |
|---|
FileCacheImageOutputStream(OutputStream stream,
File cacheDir)
Constructs a
FileCacheImageOutputStream that will write
to a given outputStream. |
| Modifier and Type | Method and Description |
|---|---|
void |
close()
Closes this
FileCacheImageOutputStream. |
void |
flushBefore(long pos)
Discards the initial portion of the stream prior to the
indicated position.
|
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.
|
flushBits, write, writeBit, writeBits, writeBoolean, writeByte, writeBytes, writeChar, writeChars, writeChars, writeDouble, writeDoubles, writeFloat, writeFloats, writeInt, writeInts, writeLong, writeLongs, writeShort, writeShorts, writeUTFcheckClosed, 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, skipBytesclone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, waitflush, 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, skipBytespublic FileCacheImageOutputStream(OutputStream stream, File cacheDir) throws IOException
FileCacheImageOutputStream that will write
to a given outputStream.
A temporary file is used as a cache. If
cacheDiris 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.public int read()
throws IOException
ImageInputStreamImplint 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 ImageInputStreamread 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
ImageInputStreamImpllen 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 ImageInputStreamread in class ImageInputStreamImplb - 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
ImageOutputStreamb 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
flushBits
method of ImageOutputStreamImpl
to guarantee this.
write in interface DataOutputwrite in interface ImageOutputStreamwrite in class ImageOutputStreamImplb - 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
ImageOutputStreamlen 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
flushBits
method of ImageOutputStreamImpl
to guarantee this.
write in interface DataOutputwrite in interface ImageOutputStreamwrite in class ImageOutputStreamImplb - an array of bytes to be written.off - the start offset in the data.len - the number of bytes 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 ImageInputStreamlength in class ImageInputStreamImplpublic 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 ImageInputStreamseek in class ImageInputStreamImplpos - 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 ImageInputStreamisCached in class ImageInputStreamImpltrue.isCachedMemory(),
isCachedFile()public boolean isCachedFile()
true since this
ImageOutputStream maintains a file cache.isCachedFile in interface ImageInputStreamisCachedFile in class ImageInputStreamImpltrue.isCached(),
isCachedMemory()public boolean isCachedMemory()
false since this
ImageOutputStream does not maintain a main memory
cache.isCachedMemory in interface ImageInputStreamisCachedMemory in class ImageInputStreamImplfalse.isCached(),
isCachedFile()public void close()
throws IOException
FileCacheImageOutputStream. 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 Closeableclose in interface AutoCloseableclose in interface ImageInputStreamclose in class ImageInputStreamImplIOException - if an error occurs.public void flushBefore(long pos)
throws IOException
ImageInputStreamIndexOutOfBoundsException.
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 ImageInputStreamflushBefore in interface ImageOutputStreamflushBefore in class ImageInputStreamImplpos - a long containing the length of the
stream prefix that may be flushed.IOException - if an I/O error occurs. Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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