Java javax.imageio.spi Class ImageOutputStreamSpi（JDK8）

Field Detail

• outputClass

  protected Class<?> outputClass

  A Class object indicating the legal object type for use by the createInputStreamInstance method.

Constructor Detail

• ImageOutputStreamSpi

  protected ImageOutputStreamSpi()

  Constructs a blank ImageOutputStreamSpi. It is up to the subclass to initialize instance variables and/or override method implementations in order to provide working versions of all methods.

• ImageOutputStreamSpi

  public ImageOutputStreamSpi(String vendorName,
                              String version,
                              Class<?> outputClass)

  Constructs an ImageOutputStreamSpi with a given set of values.

  Parameters:

  vendorName - the vendor name.

  version - a version identifier.

  outputClass - a Class object indicating the legal object type for use by the createOutputStreamInstance method.

  Throws:

  IllegalArgumentException - if vendorName is null.

  IllegalArgumentException - if version is null.

Method Detail

• getOutputClass

  public Class<?> getOutputClass()

  Returns a Class object representing the class or interface type that must be implemented by an output destination in order to be "wrapped" in an ImageOutputStream via the createOutputStreamInstance method.

  Typical return values might include OutputStream.class or File.class, but any class may be used.

  Returns:

  a Class variable.

  See Also:

  createOutputStreamInstance(Object, boolean, File)

• canUseCacheFile

  public boolean canUseCacheFile()

  Returns true if the ImageOutputStream implementation associated with this service provider can optionally make use of a cache File for improved performance and/or memory footrprint. If false, the value of the cacheFile argument to createOutputStreamInstance will be ignored.

  The default implementation returns false.

  Returns:

  true if a cache file can be used by the output streams created by this service provider.

• needsCacheFile

  public boolean needsCacheFile()

  Returns true if the ImageOutputStream implementation associated with this service provider requires the use of a cache File.

  The default implementation returns false.

  Returns:

  true if a cache file is needed by the output streams created by this service provider.

• createOutputStreamInstance

  public abstract ImageOutputStream createOutputStreamInstance(Object output,
                                                               boolean useCache,
                                                               File cacheDir)
                                                        throws IOException

  Returns an instance of the ImageOutputStream implementation associated with this service provider. If the use of a cache file is optional, the useCache parameter will be consulted. Where a cache is required, or not applicable, the value of useCache will be ignored.

  Parameters:

  output - an object of the class type returned by getOutputClass.

  useCache - a boolean indicating whether a cache file should be used, in cases where it is optional.

  cacheDir - a File indicating where the cache file should be created, or null to use the system directory.

  Returns:

  an ImageOutputStream instance.

  Throws:

  IllegalArgumentException - if output is not an instance of the correct class or is null.

  IllegalArgumentException - if a cache file is needed, but cacheDir is non-null and is not a directory.

  IOException - if a cache file is needed but cannot be created.

  See Also:

  getOutputClass()

• createOutputStreamInstance

  public ImageOutputStream createOutputStreamInstance(Object output)
                                               throws IOException

  Returns an instance of the ImageOutputStream implementation associated with this service provider. A cache file will be created in the system-dependent default temporary-file directory, if needed.

  Parameters:

  output - an object of the class type returned by getOutputClass.

  Returns:

  an ImageOutputStream instance.

  Throws:

  IllegalArgumentException - if output is not an instance of the correct class or is null.

  IOException - if a cache file is needed but cannot be created.

  See Also:

  getOutputClass()