Module java.desktop
Package javax.imageio.stream

Class FileCacheImageInputStream

java.lang.Object
javax.imageio.stream.ImageInputStreamImpl
javax.imageio.stream.FileCacheImageInputStream
All Implemented Interfaces:
Closeable, DataInput, AutoCloseable, ImageInputStream
public class FileCacheImageInputStream extends ImageInputStreamImpl
An implementation of ImageInputStream that gets its input from a regular InputStream. A file is used to cache previously read data.

  • Constructor Details

    • FileCacheImageInputStream

      public FileCacheImageInputStream(InputStream stream, File cacheDir) throws IOException
      Constructs a FileCacheImageInputStream that will read from a given InputStream.

      A temporary file is used as a cache. If cacheDir is non-null and is a directory, the file will be created there. If it is null, the system-dependent default temporary-file directory will be used (see the documentation for File.createTempFile for details).

      Parameters:
      stream - an InputStream to read from.
      cacheDir - a File indicating where the cache file should be created, or null to use the system directory.
      Throws:
      IllegalArgumentException - if stream is null.
      IllegalArgumentException - if cacheDir is non-null but is not a directory.
      IOException - if a cache file cannot be created.

  • 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:

    • isCachedFile

      public boolean isCachedFile()
      Returns true since this ImageInputStream maintains a file cache.
      Specified by:
      isCachedFile in interface ImageInputStream
      Overrides:
      isCachedFile in class ImageInputStreamImpl
      Returns:
      true.
      See Also:

    • isCachedMemory

      public boolean isCachedMemory()
      Returns false since this ImageInputStream does not maintain a main memory cache.
      Specified by:
      isCachedMemory in interface ImageInputStream
      Overrides:
      isCachedMemory in class ImageInputStreamImpl
      Returns:
      false.
      See Also:

    • close

      public void close() throws IOException
      Closes this FileCacheImageInputStream, closing and removing the cache file. The source InputStream is not closed.
      Throws:
      IOException - if an 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: