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

Constructor Summary
Constructors
Constructor and Description

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

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Method Summary

Methods
Modifier and Type	Method and Description
`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 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`.

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Methods inherited from class javax.imageio.stream.ImageInputStreamImpl checkClosed, flush, 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 inherited from class java.lang.Object clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 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 - if stream is null.
- Method Detail
  - 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.
  - flushBefore
    public void flushBefore(long pos) throws IOException
    
    Description copied from interface: ImageInputStream
    
    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 an IndexOutOfBoundsException.
    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 in interface ImageInputStream
    
    Overrides:
    
    flushBefore in class ImageInputStreamImpl
    
    Parameters:
    pos - a long containing the length of the stream prefix that may be flushed.
    
    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.
    
    Specified by:
    
    close in interface Closeable
    
    Specified by:
    
    close in interface AutoCloseable
    
    Specified by:
    
    close in interface ImageInputStream
    
    Overrides:
    
    close in class ImageInputStreamImpl
    
    Throws:
    
    IOException - if an I/O error occurs.
  - finalize
    protected void finalize() throws Throwable
    
    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.

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Dokument erstellt 11/06/2005, zuletzt geändert 04/03/2020
Quelle des gedruckten Dokuments:https://www.gaudry.be/de/java-api-rf-javax/imageio/stream/MemoryCacheImageInputStream.html

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Referenzen

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Class MemoryCacheImageInputStream

Referenzen