javax.imageio.stream

Class FileCacheImageOutputStream

    • Constructor Detail

      • FileCacheImageOutputStream

        public FileCacheImageOutputStream(OutputStream stream,
                                  File cacheDir)
                                   throws IOException
        Constructs a FileCacheImageOutputStream that will write to a given outputStream.

        A temporary file is used as a cache. If cacheDiris 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 OutputStream to write to.
        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 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.
      • write

        public void write(int b)
                   throws IOException
        Description copied from interface: ImageOutputStream
        Writes a single byte to the stream at the current position. The 24 high-order bits of b are ignored.

        If the bit offset within the stream is non-zero, the remainder of the current byte is padded with 0s and written out first. The bit offset will be 0 after the write. Implementers can use the flushBits method of ImageOutputStreamImpl to guarantee this.

        Specified by:
        write in interface DataOutput
        Specified by:
        write in interface ImageOutputStream
        Specified by:
        write in class ImageOutputStreamImpl
        Parameters:
        b - an int whose lower 8 bits are to be written.
        Throws:
        IOException - if an I/O error occurs.
      • write

        public void write(byte[] b,
                 int off,
                 int len)
                   throws IOException
        Description copied from interface: ImageOutputStream
        Writes a sequence of bytes to the stream at the current position. If len is 0, nothing is written. The byte b[off] is written first, then the byte b[off + 1], and so on.

        If the bit offset within the stream is non-zero, the remainder of the current byte is padded with 0s and written out first. The bit offset will be 0 after the write. Implementers can use the flushBits method of ImageOutputStreamImpl to guarantee this.

        Specified by:
        write in interface DataOutput
        Specified by:
        write in interface ImageOutputStream
        Specified by:
        write in class ImageOutputStreamImpl
        Parameters:
        b - an array of bytes to be written.
        off - the start offset in the data.
        len - the number of bytes to write.
        Throws:
        IOException - if an I/O error occurs.
      • length

        public long length()
        Description copied from class: ImageInputStreamImpl
        Returns -1L to indicate that the stream has unknown length. Subclasses must override this method to provide actual length information.
        Specified by:
        length in interface ImageInputStream
        Overrides:
        length in class ImageInputStreamImpl
        Returns:
        -1L to indicate unknown length.
      • seek

        public void seek(long pos)
                  throws IOException
        Sets the current stream position and resets the bit offset to 0. It is legal to seek past the end of the file; an EOFException will be thrown only if a read is performed. The file length will not be increased until a write is performed.
        Specified by:
        seek in interface ImageInputStream
        Overrides:
        seek in class ImageInputStreamImpl
        Parameters:
        pos - a long containing the desired file pointer position.
        Throws:
        IndexOutOfBoundsException - if pos is smaller than the flushed position.
        IOException - if any other 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
        Specified by:
        flushBefore in interface ImageOutputStream
        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.

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Document créé le 21/07/2006, dernière modification le 29/10/2018
Source du document imprimé : https://www.gaudry.be/java-api-rf-javax/imageio/stream/FileCacheImageOutputStream.html

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