Class ImageInputStreamSpi
- java.lang.Object
-
- javax.imageio.spi.IIOServiceProvider
-
- javax.imageio.spi.ImageInputStreamSpi
- All Implemented Interfaces:
RegisterableService
public abstract class ImageInputStreamSpi extends IIOServiceProvider
The service provider interface (SPI) for ImageInputStream
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 ImageInputStream
. For example, a particular ImageInputStreamSpi
might allow a generic InputStream
to be used as an input source; another might take input from a URL
.
By treating the creation of ImageInputStream
s as a pluggable service, it becomes possible to handle future input sources without changing the API. Also, high-performance implementations of ImageInputStream
(for example, native implementations for a particular platform) can be installed and used transparently by applications.
- See Also:
-
IIORegistry
,ImageInputStream
Field Summary
Modifier and Type | Field | Description |
---|---|---|
protected Class<?> | inputClass | A |
Fields declared in class javax.imageio.spi.IIOServiceProvider
vendorName, version
Constructor Summary
Modifier | Constructor | Description |
---|---|---|
protected | ImageInputStreamSpi() | Constructs a blank |
ImageInputStreamSpi(String vendorName,
String version,
Class<?> inputClass) | Constructs an |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
boolean | canUseCacheFile() | Returns |
ImageInputStream | createInputStreamInstance(Object input) | Returns an instance of the |
abstract ImageInputStream | createInputStreamInstance(Object input,
boolean useCache,
File cacheDir) | Returns an instance of the |
Class<?> | getInputClass() | 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
inputClass
protected Class<?> inputClass
A Class
object indicating the legal object type for use by the createInputStreamInstance
method.
Constructor Detail
ImageInputStreamSpi
protected ImageInputStreamSpi()
Constructs a blank ImageInputStreamSpi
. It is up to the subclass to initialize instance variables and/or override method implementations in order to provide working versions of all methods.
ImageInputStreamSpi
public ImageInputStreamSpi(String vendorName, String version, Class<?> inputClass)
Constructs an ImageInputStreamSpi
with a given set of values.
- Parameters:
-
vendorName
- the vendor name. -
version
- a version identifier. -
inputClass
- aClass
object indicating the legal object type for use by thecreateInputStreamInstance
method. - Throws:
-
IllegalArgumentException
- ifvendorName
isnull
. -
IllegalArgumentException
- ifversion
isnull
.
Method Detail
getInputClass
public Class<?> getInputClass()
Returns a Class
object representing the class or interface type that must be implemented by an input source in order to be "wrapped" in an ImageInputStream
via the createInputStreamInstance
method.
Typical return values might include InputStream.class
or URL.class
, but any class may be used.
- Returns:
- a
Class
variable. - See Also:
createInputStreamInstance(Object, boolean, File)
canUseCacheFile
public boolean canUseCacheFile()
Returns true
if the ImageInputStream
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 useCache
argument to createInputStreamInstance
will be ignored.
The default implementation returns false
.
- Returns:
-
true
if a cache file can be used by the input streams created by this service provider.
needsCacheFile
public boolean needsCacheFile()
Returns true
if the ImageInputStream
implementation associated with this service provider requires the use of a cache File
. If true
, the value of the useCache
argument to createInputStreamInstance
will be ignored.
The default implementation returns false
.
- Returns:
-
true
if a cache file is needed by the input streams created by this service provider.
createInputStreamInstance
public abstract ImageInputStream createInputStreamInstance(Object input, boolean useCache, File cacheDir) throws IOException
Returns an instance of the ImageInputStream
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:
-
input
- an object of the class type returned bygetInputClass
. -
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
ImageInputStream
instance. - Throws:
-
IllegalArgumentException
- ifinput
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:
-
getInputClass()
,canUseCacheFile()
,needsCacheFile()
createInputStreamInstance
public ImageInputStream createInputStreamInstance(Object input) throws IOException
Returns an instance of the ImageInputStream
implementation associated with this service provider. A cache file will be created in the system-dependent default temporary-file directory, if needed.
- Parameters:
-
input
- an object of the class type returned bygetInputClass
. - Returns:
- an
ImageInputStream
instance. - Throws:
-
IllegalArgumentException
- ifinput
is not an instance of the correct class or isnull
. -
IOException
- if a cache file is needed but cannot be created. - See Also:
getInputClass()