MemoryCacheImageInputStream (Java 2 Platform SE 5.0) (original) (raw)

javax.imageio.stream

Class MemoryCacheImageInputStream

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

All Implemented Interfaces:

DataInput, ImageInputStream

public class MemoryCacheImageInputStream

extends ImageInputStreamImpl

An implementation of ImageInputStream that gets its input from a regular InputStream. A memory buffer is used to cache at least the data between the discard position and the current read position.

In general, it is preferable to use aFileCacheImageInputStream when reading from a regularInputStream. This class is provided for cases where it is not possible to create a writable temporary file.

Field Summary

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

Constructor Summary
MemoryCacheImageInputStream(InputStream stream) Constructs a MemoryCacheImageInputStream that will read from a given InputStream.

Method Summary
void	close() Closes this MemoryCacheImageInputStream, freeing the cache.
void	flushBefore(long pos) Discards the initial portion of the stream prior to the indicated postion.
boolean	isCached() Returns true since thisImageInputStream caches data in order to allow seeking backwards.
boolean	isCachedFile() Returns false since thisImageInputStream does not maintain a file cache.
boolean	isCachedMemory() Returns true since thisImageInputStream maintains a main memory cache.
int	read() Reads a single byte from the stream and returns it as an integer between 0 and 255.
int	[read](../../../javax/imageio/stream/MemoryCacheImageInputStream.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, finalize, flush, 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, finalize, flush, 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

MemoryCacheImageInputStream

public MemoryCacheImageInputStream(InputStream stream)

Constructs a MemoryCacheImageInputStream that will read from a given InputStream.

Parameters:

stream - an InputStream to read from.

Throws:

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

Method Detail

read

public int read() throws IOException

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

Reads a single byte from the stream and returns it as an integer between 0 and 255. If the end of the stream is reached, -1 is returned.

The bit offset within the stream is 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:

a byte value from the stream, as an int, or -1 to indicate EOF.

Throws:

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

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.

flushBefore

public void flushBefore(long pos) throws IOException

Description copied from interface: [ImageInputStream](../../../javax/imageio/stream/ImageInputStream.html#flushBefore%28long%29)

Discards the initial portion of the stream prior to the indicated postion. Attempting to seek to an offset within the flushed portion of the stream will result in anIndexOutOfBoundsException.

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.

Specified by:

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

Overrides:

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

Parameters:

pos - a long containing the length of the file prefix that may be flushed.

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 false since thisImageInputStream does not maintain 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:

false.

See Also:

isCached(), isCachedMemory()

isCachedMemory

public boolean isCachedMemory()

Returns true since thisImageInputStream maintains 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:

true.

See Also:

isCached(), isCachedFile()

close

public void close() throws IOException

Closes this MemoryCacheImageInputStream, freeing the cache. 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 I/O error occurs.

Submit a bug or feature
For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.