MemoryCacheImageInputStream (Java Platform SE 6) (original) (raw)
javax.imageio.stream
Class MemoryCacheImageInputStream
java.lang.Object
javax.imageio.stream.ImageInputStreamImpl
javax.imageio.stream.MemoryCacheImageInputStream
All Implemented Interfaces:
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. |
| protected void | finalize() Finalizes this object prior to garbage collection. |
| 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 anint 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, 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 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.
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 stream 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:
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:
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.
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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