FileCacheImageInputStream (Java Platform SE 6) (original) (raw)

javax.imageio.stream

Class FileCacheImageInputStream

java.lang.Object extended by javax.imageio.stream.ImageInputStreamImpl javax.imageio.stream.FileCacheImageInputStream

All Implemented Interfaces:

DataInput, ImageInputStream

public class FileCacheImageInputStream

extends ImageInputStreamImpl

An implementation of ImageInputStream that gets its input from a regular InputStream. A file is used to cache previously read data.

Field Summary

Fields inherited from class javax.imageio.stream.ImageInputStreamImpl
bitOffset, byteOrder, flushedPos, streamPos

Constructor Summary
[FileCacheImageInputStream](../../../javax/imageio/stream/FileCacheImageInputStream.html#FileCacheImageInputStream%28java.io.InputStream, java.io.File%29)(InputStream stream,File cacheDir) Constructs a FileCacheImageInputStream that will read from a given InputStream.

Method Summary
void	close() Closes this FileCacheImageInputStream, closing and removing the cache file.
protected void	finalize() Finalizes this object prior to garbage collection.
boolean	isCached() Returns true since thisImageInputStream caches data in order to allow seeking backwards.
boolean	isCachedFile() Returns true since thisImageInputStream maintains a file cache.
boolean	isCachedMemory() Returns false 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](../../../javax/imageio/stream/FileCacheImageInputStream.html#read%28byte[], int, int%29)(byte[] b, int off, int len) Reads up to len bytes from the stream, and stores them into b starting at index off.

Methods inherited from class javax.imageio.stream.ImageInputStreamImpl
checkClosed, flush, flushBefore, getBitOffset, getByteOrder, getFlushedPosition, getStreamPosition, length, mark, read, readBit, readBits, readBoolean, readByte, [readBytes](../../../javax/imageio/stream/ImageInputStreamImpl.html#readBytes%28javax.imageio.stream.IIOByteBuffer, int%29), readChar, readDouble, readFloat, readFully, [readFully](../../../javax/imageio/stream/ImageInputStreamImpl.html#readFully%28byte[], int, int%29), [readFully](../../../javax/imageio/stream/ImageInputStreamImpl.html#readFully%28char[], int, int%29), [readFully](../../../javax/imageio/stream/ImageInputStreamImpl.html#readFully%28double[], int, int%29), [readFully](../../../javax/imageio/stream/ImageInputStreamImpl.html#readFully%28float[], int, int%29), [readFully](../../../javax/imageio/stream/ImageInputStreamImpl.html#readFully%28int[], int, int%29), [readFully](../../../javax/imageio/stream/ImageInputStreamImpl.html#readFully%28long[], int, int%29), [readFully](../../../javax/imageio/stream/ImageInputStreamImpl.html#readFully%28short[], int, int%29), readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedInt, readUnsignedShort, readUTF, reset, seek, setBitOffset, setByteOrder, skipBytes, skipBytes

Methods inherited from class javax.imageio.stream.ImageInputStreamImpl

checkClosed, flush, flushBefore, getBitOffset, getByteOrder, getFlushedPosition, getStreamPosition, length, mark, read, readBit, readBits, readBoolean, readByte, [readBytes](../../../javax/imageio/stream/ImageInputStreamImpl.html#readBytes%28javax.imageio.stream.IIOByteBuffer, int%29), readChar, readDouble, readFloat, readFully, [readFully](../../../javax/imageio/stream/ImageInputStreamImpl.html#readFully%28byte[], int, int%29), [readFully](../../../javax/imageio/stream/ImageInputStreamImpl.html#readFully%28char[], int, int%29), [readFully](../../../javax/imageio/stream/ImageInputStreamImpl.html#readFully%28double[], int, int%29), [readFully](../../../javax/imageio/stream/ImageInputStreamImpl.html#readFully%28float[], int, int%29), [readFully](../../../javax/imageio/stream/ImageInputStreamImpl.html#readFully%28int[], int, int%29), [readFully](../../../javax/imageio/stream/ImageInputStreamImpl.html#readFully%28long[], int, int%29), [readFully](../../../javax/imageio/stream/ImageInputStreamImpl.html#readFully%28short[], int, int%29), readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedInt, readUnsignedShort, readUTF, reset, seek, setBitOffset, setByteOrder, skipBytes, skipBytes

Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, [wait](../../../java/lang/Object.html#wait%28long, int%29)

Constructor Detail

FileCacheImageInputStream

public FileCacheImageInputStream(InputStream stream, File cacheDir) throws IOException

Constructs a FileCacheImageInputStream that will read from a given InputStream.

A temporary file is used as a cache. IfcacheDiris 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 - an InputStream to read from.

cacheDir - a File indicating where the cache file should be created, or null to use the system directory.

Throws:

[IllegalArgumentException](../../../java/lang/IllegalArgumentException.html "class in java.lang") - if stream isnull.

[IllegalArgumentException](../../../java/lang/IllegalArgumentException.html "class in java.lang") - if cacheDir is non-null but is not a directory.

[IOException](../../../java/io/IOException.html "class in java.io") - if a cache file cannot be created.

Method Detail

read

public int read() throws IOException

Description copied from class: [ImageInputStreamImpl](../../../javax/imageio/stream/ImageInputStreamImpl.html#read%28%29)

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](../../../javax/imageio/stream/ImageInputStream.html#read%28%29) in interface [ImageInputStream](../../../javax/imageio/stream/ImageInputStream.html "interface in javax.imageio.stream")

Specified by:

[read](../../../javax/imageio/stream/ImageInputStreamImpl.html#read%28%29) in class [ImageInputStreamImpl](../../../javax/imageio/stream/ImageInputStreamImpl.html "class in javax.imageio.stream")

Returns:

the value of the next byte in the stream, or -1 if EOF is reached.

Throws:

[IOException](../../../java/io/IOException.html "class in java.io") - if the stream has been closed.

read

public int read(byte[] b, int off, int len) throws IOException

Description copied from class: [ImageInputStreamImpl](../../../javax/imageio/stream/ImageInputStreamImpl.html#read%28byte[], int, int%29)

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.

Specified by:

[read](../../../javax/imageio/stream/ImageInputStream.html#read%28byte[], int, int%29) in interface [ImageInputStream](../../../javax/imageio/stream/ImageInputStream.html "interface in javax.imageio.stream")

Specified by:

[read](../../../javax/imageio/stream/ImageInputStreamImpl.html#read%28byte[], int, int%29) in class [ImageInputStreamImpl](../../../javax/imageio/stream/ImageInputStreamImpl.html "class in javax.imageio.stream")

Parameters:

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.

Returns:

the number of bytes actually read, or -1 to indicate EOF.

Throws:

[IOException](../../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

isCached

public boolean isCached()

Returns true since thisImageInputStream caches data in order to allow seeking backwards.

Specified by:

[isCached](../../../javax/imageio/stream/ImageInputStream.html#isCached%28%29) in interface [ImageInputStream](../../../javax/imageio/stream/ImageInputStream.html "interface in javax.imageio.stream")

Overrides:

[isCached](../../../javax/imageio/stream/ImageInputStreamImpl.html#isCached%28%29) in class [ImageInputStreamImpl](../../../javax/imageio/stream/ImageInputStreamImpl.html "class in javax.imageio.stream")

Returns:

true.

See Also:

isCachedMemory(), isCachedFile()

isCachedFile

public boolean isCachedFile()

Returns true since thisImageInputStream maintains a file cache.

Specified by:

[isCachedFile](../../../javax/imageio/stream/ImageInputStream.html#isCachedFile%28%29) in interface [ImageInputStream](../../../javax/imageio/stream/ImageInputStream.html "interface in javax.imageio.stream")

Overrides:

[isCachedFile](../../../javax/imageio/stream/ImageInputStreamImpl.html#isCachedFile%28%29) in class [ImageInputStreamImpl](../../../javax/imageio/stream/ImageInputStreamImpl.html "class in javax.imageio.stream")

Returns:

true.

See Also:

isCached(), isCachedMemory()

isCachedMemory

public boolean isCachedMemory()

Returns false since thisImageInputStream does not maintain a main memory cache.

Specified by:

[isCachedMemory](../../../javax/imageio/stream/ImageInputStream.html#isCachedMemory%28%29) in interface [ImageInputStream](../../../javax/imageio/stream/ImageInputStream.html "interface in javax.imageio.stream")

Overrides:

[isCachedMemory](../../../javax/imageio/stream/ImageInputStreamImpl.html#isCachedMemory%28%29) in class [ImageInputStreamImpl](../../../javax/imageio/stream/ImageInputStreamImpl.html "class in javax.imageio.stream")

Returns:

false.

See Also:

isCached(), isCachedFile()

close

public void close() throws IOException

Closes this FileCacheImageInputStream, closing and removing the cache file. The source InputStream is not closed.

Specified by:

[close](../../../javax/imageio/stream/ImageInputStream.html#close%28%29) in interface [ImageInputStream](../../../javax/imageio/stream/ImageInputStream.html "interface in javax.imageio.stream")

Overrides:

[close](../../../javax/imageio/stream/ImageInputStreamImpl.html#close%28%29) in class [ImageInputStreamImpl](../../../javax/imageio/stream/ImageInputStreamImpl.html "class in javax.imageio.stream")

Throws:

[IOException](../../../java/io/IOException.html "class in java.io") - if an error occurs.

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](../../../javax/imageio/stream/ImageInputStreamImpl.html#finalize%28%29) in class [ImageInputStreamImpl](../../../javax/imageio/stream/ImageInputStreamImpl.html "class in javax.imageio.stream")

Throws:

[Throwable](../../../java/lang/Throwable.html "class in java.lang") - if an error occurs during superclass finalization.

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For further API reference and developer documentation, see Java SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

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