Module java.desktop

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.

  • 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") protected void finalize() throws Throwable
      Deprecated.
      The finalize method has been deprecated. Subclasses that override finalize in order to perform cleanup should be modified to use alternative cleanup mechanisms and to remove the overriding finalize method. When overriding the finalize method, its implementation must explicitly ensure that super.finalize() is invoked as described in Object.finalize(). See the specification for Object.finalize() for further information 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