Class MemoryCacheImageInputStream

java.lang.Object

javax.imageio.stream.ImageInputStreamImpl

javax.imageio.stream.MemoryCacheImageInputStream

All Implemented Interfaces:

Closeable, DataInput, AutoCloseable, 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 a FileCacheImageInputStream when reading from a regular InputStream. This class is provided for cases where it is not possible to create a writable temporary file.

Field Summary

Fields declared in class javax.imageio.stream.ImageInputStreamImpl

bitOffset, byteOrder, flushedPos, streamPos

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	Description
void	close()	Closes this MemoryCacheImageInputStream, freeing the cache.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. Finalization has been deprecated for removal.
boolean	isCached()	Returns true since this ImageInputStream caches data in order to allow seeking backwards.
boolean	isCachedFile()	Returns false since this ImageInputStream does not maintain a file cache.
boolean	isCachedMemory()	Returns true since this ImageInputStream maintains a main memory cache.
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.

Methods declared in 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

Methods declared in class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

MemoryCacheImageInputStream

public MemoryCacheImageInputStream(InputStream stream)

Constructs a MemoryCacheImageInputStream that will read from a given InputStream.

Parameters:

stream - an InputStream to read from.

Throws:

IllegalArgumentException - if stream is null.

Method Details

read

public int read()
         throws IOException

Description copied from class: ImageInputStreamImpl

Reads a single byte from the stream and returns it as an int 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 interface ImageInputStream

Specified by:

read in class ImageInputStreamImpl

Returns:

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

Throws:

IOException - if the stream has been closed.

read

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

Description copied from class: ImageInputStreamImpl

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 in interface ImageInputStream

Specified by:

read in class ImageInputStreamImpl

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 - if an I/O error occurs.

isCached

public boolean isCached()

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

Specified by:

isCached in interface ImageInputStream

Overrides:

isCached in class ImageInputStreamImpl

Returns:

true.

See Also:

• isCachedMemory()
• isCachedFile()

isCachedFile

public boolean isCachedFile()

Returns false since this ImageInputStream does not maintain a file cache.

Specified by:

isCachedFile in interface ImageInputStream

Overrides:

isCachedFile in class ImageInputStreamImpl

Returns:

false.

See Also:

• isCached()
• isCachedMemory()

isCachedMemory

public boolean isCachedMemory()

Returns true since this ImageInputStream maintains a main memory cache.

Specified by:

isCachedMemory in interface ImageInputStream

Overrides:

isCachedMemory in class ImageInputStreamImpl

Returns:

true.

See Also:

• isCached()
• isCachedFile()

close

public void close()
           throws IOException

Closes this MemoryCacheImageInputStream, freeing the cache. The source InputStream is not closed.

Throws:

IOException - if an I/O error occurs.

finalize

@Deprecated(since="9",
            forRemoval=true)
protected void finalize()
                 throws Throwable

Deprecated, for removal: This API element is subject to removal in a future version.

Finalization has been deprecated for removal. See Object.finalize() for background information and details about migration options.

Finalizes this object prior to garbage collection. The close method is called to close any open input source. This method should not be called from application code.

Overrides:

finalize in class ImageInputStreamImpl

Throws:

Throwable - if an error occurs during superclass finalization.

See Also:

• WeakReference
• PhantomReference