4.6 Writing Stream Plug-ins

The standard classes in the javax.imageio.stream package are able to create ImageInputStreams and ImageOutputStreams that:

• Read from a File
• Read from an InputStream, using a temporary File as a cache
• Read from an InputStream, using a byte array in memory as a cache
• Write to a File
• Write to an OutputStream, using a temporary File as a cache
• Write to an OutputStream, using a byte array in memory as a cache

It is possible to write new implementations of ImageInputStream and InmageOutputStream that interface with other I/O primitives (for example, databases or future fast I/O interfaces). The ImageInputStreamImpl and ImageOutputStreamImpl classes provide a base for subclassing. Only a handful of methods are required to be implemented by the subclass, although it is possible to implement more for greater efficiency:

• int read()
• int read(byte[] b, int off, int len)
• write(int b)
• write(byte[] b, int off, int len)
• seek(long pos)