- java.lang.Object
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- javax.imageio.stream.ImageInputStreamImpl
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- javax.imageio.stream.FileCacheImageInputStream
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- All Implemented Interfaces:
- Closeable, DataInput, AutoCloseable, ImageInputStream
public class FileCacheImageInputStream extends ImageInputStreamImpl
An implementation ofImageInputStream
that gets its input from a regularInputStream
. A file is used to cache previously read data.
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Field Summary
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Fields inherited from class javax.imageio.stream.ImageInputStreamImpl
bitOffset, byteOrder, flushedPos, streamPos
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Constructor Summary
Constructors Constructor and Description FileCacheImageInputStream(InputStream stream, File cacheDir)
Constructs aFileCacheImageInputStream
that will read from a givenInputStream
.
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Method Summary
Methods Modifier and Type Method and Description void
close()
Closes thisFileCacheImageInputStream
, closing and removing the cache file.protected void
finalize()
Finalizes this object prior to garbage collection.boolean
isCached()
Returnstrue
since thisImageInputStream
caches data in order to allow seeking backwards.boolean
isCachedFile()
Returnstrue
since thisImageInputStream
maintains a file cache.boolean
isCachedMemory()
Returnsfalse
since thisImageInputStream
does not maintain a main memory cache.int
read()
Reads a single byte from the stream and returns it as anint
between 0 and 255.int
read(byte[] b, int off, int len)
Reads up tolen
bytes from the stream, and stores them intob
starting at indexoff
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Methods inherited from class javax.imageio.stream.ImageInputStreamImpl
checkClosed, flush, flushBefore, 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, seek, setBitOffset, setByteOrder, skipBytes, skipBytes
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Constructor Detail
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FileCacheImageInputStream
public FileCacheImageInputStream(InputStream stream, File cacheDir) throws IOException
Constructs aFileCacheImageInputStream
that will read from a givenInputStream
.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 isnull
, the system-dependent default temporary-file directory will be used (see the documentation forFile.createTempFile
for details).- Parameters:
stream
- anInputStream
to read from.cacheDir
- aFile
indicating where the cache file should be created, ornull
to use the system directory.- Throws:
IllegalArgumentException
- ifstream
isnull
.IllegalArgumentException
- ifcacheDir
is non-null
but is not a directory.IOException
- if a cache file cannot be created.
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Method Detail
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read
public int read() throws IOException
Description copied from class:ImageInputStreamImpl
Reads a single byte from the stream and returns it as anint
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.
- Specified by:
read
in interfaceImageInputStream
- Specified by:
read
in classImageInputStreamImpl
- Returns:
- the value of the next byte in the stream, or
-1
if EOF is reached. - Throws:
IOException
- if the stream has been closed.
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read
public int read(byte[] b, int off, int len) throws IOException
Description copied from class:ImageInputStreamImpl
Reads up tolen
bytes from the stream, and stores them intob
starting at indexoff
. 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.
- Specified by:
read
in interfaceImageInputStream
- Specified by:
read
in classImageInputStreamImpl
- Parameters:
b
- an array of bytes to be written to.off
- the starting position withinb
to write to.len
- the maximum number of bytes to read.- Returns:
- the number of bytes actually read, or
-1
to indicate EOF. - Throws:
IOException
- if an I/O error occurs.
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isCached
public boolean isCached()
Returnstrue
since thisImageInputStream
caches data in order to allow seeking backwards.- Specified by:
isCached
in interfaceImageInputStream
- Overrides:
isCached
in classImageInputStreamImpl
- Returns:
true
.- See Also:
isCachedMemory()
,isCachedFile()
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isCachedFile
public boolean isCachedFile()
Returnstrue
since thisImageInputStream
maintains a file cache.- Specified by:
isCachedFile
in interfaceImageInputStream
- Overrides:
isCachedFile
in classImageInputStreamImpl
- Returns:
true
.- See Also:
isCached()
,isCachedMemory()
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isCachedMemory
public boolean isCachedMemory()
Returnsfalse
since thisImageInputStream
does not maintain a main memory cache.- Specified by:
isCachedMemory
in interfaceImageInputStream
- Overrides:
isCachedMemory
in classImageInputStreamImpl
- Returns:
false
.- See Also:
isCached()
,isCachedFile()
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close
public void close() throws IOException
Closes thisFileCacheImageInputStream
, closing and removing the cache file. The sourceInputStream
is not closed.- Specified by:
close
in interfaceCloseable
- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceImageInputStream
- Overrides:
close
in classImageInputStreamImpl
- Throws:
IOException
- if an error occurs.
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finalize
protected void finalize() throws Throwable
Finalizes this object prior to garbage collection. Theclose
method is called to close any open input source. This method should not be called from application code.- Overrides:
finalize
in classImageInputStreamImpl
- Throws:
Throwable
- if an error occurs during superclass finalization.
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Bij voorbaat dank.
Document heeft de 11/06/2005 gemaakt, de laatste keer de 04/03/2020 gewijzigd
Bron van het afgedrukte document:https://www.gaudry.be/nl/java-api-rf-javax/imageio/stream/FileCacheImageInputStream.html
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