Class ImageOutputStreamSpi
- java.lang.Object
-
- javax.imageio.spi.IIOServiceProvider
-
- javax.imageio.spi.ImageOutputStreamSpi
- All Implemented Interfaces:
RegisterableService
public abstract class ImageOutputStreamSpi extends IIOServiceProvider
The service provider interface (SPI) for ImageOutputStream
s. For more information on service provider interfaces, see the class comment for the IIORegistry
class.
This interface allows arbitrary objects to be "wrapped" by instances of ImageOutputStream
. For example, a particular ImageOutputStreamSpi
might allow a generic OutputStream
to be used as a destination; another might output to a File
or to a device such as a serial port.
By treating the creation of ImageOutputStream
s as a pluggable service, it becomes possible to handle future output destinations without changing the API. Also, high-performance implementations of ImageOutputStream
(for example, native implementations for a particular platform) can be installed and used transparently by applications.
- See Also:
-
IIORegistry
,ImageOutputStream
Field Summary
Modifier and Type | Field | Description |
---|---|---|
protected Class<?> | outputClass | A |
Fields declared in class javax.imageio.spi.IIOServiceProvider
vendorName, version
Constructor Summary
Modifier | Constructor | Description |
---|---|---|
protected | ImageOutputStreamSpi() | Constructs a blank |
ImageOutputStreamSpi(String vendorName,
String version,
Class<?> outputClass) | Constructs an |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
boolean | canUseCacheFile() | Returns |
ImageOutputStream | createOutputStreamInstance(Object output) | Returns an instance of the |
abstract ImageOutputStream | createOutputStreamInstance(Object output,
boolean useCache,
File cacheDir) | Returns an instance of the |
Class<?> | getOutputClass() | Returns a |
boolean | needsCacheFile() | Returns |
Methods declared in class javax.imageio.spi.IIOServiceProvider
getDescription, getVendorName, getVersion, onDeregistration, onRegistration
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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
- aClass
object indicating the legal object type for use by thecreateOutputStreamInstance
method. - Throws:
-
IllegalArgumentException
- ifvendorName
isnull
. -
IllegalArgumentException
- ifversion
isnull
.
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 bygetOutputClass
. -
useCache
- aboolean
indicating whether a cache file should be used, in cases where it is optional. -
cacheDir
- aFile
indicating where the cache file should be created, ornull
to use the system directory. - Returns:
- an
ImageOutputStream
instance. - Throws:
-
IllegalArgumentException
- ifoutput
is not an instance of the correct class or isnull
. -
IllegalArgumentException
- if a cache file is needed, butcacheDir
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 bygetOutputClass
. - Returns:
- an
ImageOutputStream
instance. - Throws:
-
IllegalArgumentException
- ifoutput
is not an instance of the correct class or isnull
. -
IOException
- if a cache file is needed but cannot be created. - See Also:
getOutputClass()