Class FileCacheImageOutputStream
- All Implemented Interfaces:
Closeable,DataInput,DataOutput,AutoCloseable,ImageInputStream,ImageOutputStream
ImageOutputStream that writes its
output to a regular OutputStream. A file is used to
cache data until it is flushed to the output stream.-
Field Summary
Fields declared in class javax.imageio.stream.ImageInputStreamImpl
bitOffset, byteOrder, flushedPos, streamPos -
Constructor Summary
ConstructorsConstructorDescriptionFileCacheImageOutputStream(OutputStream stream, File cacheDir) Constructs aFileCacheImageOutputStreamthat will write to a givenoutputStream. -
Method Summary
Modifier and TypeMethodDescriptionvoidclose()Closes thisFileCacheImageOutputStream.voidflushBefore(long pos) Flushes all data prior to the given position to the underlying destination, such as anOutputStreamorFile.booleanisCached()Returnstruesince thisImageOutputStreamcaches data in order to allow seeking backwards.booleanReturnstruesince thisImageOutputStreammaintains a file cache.booleanReturnsfalsesince thisImageOutputStreamdoes not maintain a main memory cache.longlength()Returns-1Lto indicate that the stream has unknown length.intread()Reads a single byte from the stream and returns it as anintbetween 0 and 255.intread(byte[] b, int off, int len) Reads up tolenbytes from the stream, and stores them intobstarting at indexoff.voidseek(long pos) Sets the current stream position and resets the bit offset to 0.voidwrite(byte[] b, int off, int len) Writes a sequence of bytes to the stream at the current position.voidwrite(int b) Writes a single byte to the stream at the current position.Methods declared in class javax.imageio.stream.ImageOutputStreamImpl
flushBits, write, writeBit, writeBits, writeBoolean, writeByte, writeBytes, writeChar, writeChars, writeChars, writeDouble, writeDoubles, writeFloat, writeFloats, writeInt, writeInts, writeLong, writeLongs, writeShort, writeShorts, writeUTFMethods declared in class javax.imageio.stream.ImageInputStreamImpl
checkClosed, finalize, flush, getBitOffset, getByteOrder, getFlushedPosition, getStreamPosition, length, 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, skipBytesMethods declared in class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, waitMethods declared in interface javax.imageio.stream.ImageInputStream
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
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Constructor Details
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FileCacheImageOutputStream
Constructs aFileCacheImageOutputStreamthat will write to a givenoutputStream.A temporary file is used as a cache. If
cacheDiris non-nulland is a directory, the file will be created there. If it isnull, the system-dependent default temporary-file directory will be used (see the documentation forFile.createTempFilefor details).- Parameters:
stream- anOutputStreamto write to.cacheDir- aFileindicating where the cache file should be created, ornullto use the system directory.- Throws:
IllegalArgumentException- ifstreamisnull.IllegalArgumentException- ifcacheDiris non-nullbut is not a directory.IOException- if a cache file cannot be created.
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Method Details
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read
Description copied from class:ImageInputStreamImplReads a single byte from the stream and returns it as anintbetween 0 and 255. If EOF is reached,-1is 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.
- Specified by:
readin interfaceImageInputStream- Specified by:
readin classImageInputStreamImpl- Returns:
- the value of the next byte in the stream, or
-1if EOF is reached. - Throws:
IOException- if the stream has been closed.
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read
Description copied from class:ImageInputStreamImplReads up tolenbytes from the stream, and stores them intobstarting at indexoff. If no bytes can be read because the end of the stream has been reached,-1is 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.
- Specified by:
readin interfaceImageInputStream- Specified by:
readin classImageInputStreamImpl- Parameters:
b- an array of bytes to be written to.off- the starting position withinbto write to.len- the maximum number of bytes to read.- Returns:
- the number of bytes actually read, or
-1to indicate EOF. - Throws:
IOException- if an I/O error occurs.
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write
Description copied from interface:ImageOutputStreamWrites a single byte to the stream at the current position. The 24 high-order bits ofbare 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
flushBitsmethod ofImageOutputStreamImplto guarantee this.- Parameters:
b- anintwhose lower 8 bits are to be written.- Throws:
IOException- if an I/O error occurs.
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write
Description copied from interface:ImageOutputStreamWrites a sequence of bytes to the stream at the current position. Iflenis 0, nothing is written. The byteb[off]is written first, then the byteb[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
flushBitsmethod ofImageOutputStreamImplto guarantee this.- Parameters:
b- an array ofbytes to be written.off- the start offset in the data.len- the number ofbytes to write.- Throws:
IOException- if an I/O error occurs.
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length
public long length()Description copied from class:ImageInputStreamImplReturns-1Lto indicate that the stream has unknown length. Subclasses must override this method to provide actual length information.- Specified by:
lengthin interfaceImageInputStream- Overrides:
lengthin classImageInputStreamImpl- Returns:
- -1L to indicate unknown length.
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seek
Sets the current stream position and resets the bit offset to 0. It is legal to seek past the end of the file; anEOFExceptionwill be thrown only if a read is performed. The file length will not be increased until a write is performed.- Parameters:
pos- alongcontaining the desired file pointer position.- Throws:
IndexOutOfBoundsException- ifposis smaller than the flushed position.IOException- if any other I/O error occurs.
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isCached
public boolean isCached()Returnstruesince thisImageOutputStreamcaches data in order to allow seeking backwards.- Specified by:
isCachedin interfaceImageInputStream- Overrides:
isCachedin classImageInputStreamImpl- Returns:
true.- See Also:
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isCachedFile
public boolean isCachedFile()Returnstruesince thisImageOutputStreammaintains a file cache.- Specified by:
isCachedFilein interfaceImageInputStream- Overrides:
isCachedFilein classImageInputStreamImpl- Returns:
true.- See Also:
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isCachedMemory
public boolean isCachedMemory()Returnsfalsesince thisImageOutputStreamdoes not maintain a main memory cache.- Specified by:
isCachedMemoryin interfaceImageInputStream- Overrides:
isCachedMemoryin classImageInputStreamImpl- Returns:
false.- See Also:
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close
Closes thisFileCacheImageOutputStream. All pending data is flushed to the output, and the cache file is closed and removed. The destinationOutputStreamis not closed.- Throws:
IOException- if an error occurs.
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flushBefore
Flushes all data prior to the given position to the underlying destination, such as anOutputStreamorFile. Attempting to seek to the flushed portion of the stream will result in anIndexOutOfBoundsException.- Parameters:
pos- alongcontaining the length of the stream prefix that may be flushed to the destination.- Throws:
IOException- if an I/O error occurs.
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