org.geotools.data.pickle
Class PickledFeatureProtocol

java.lang.Object
  org.geotools.data.pickle.PickledFeatureProtocol

public abstract class PickledFeatureProtocol

extends java.lang.Object

PickledFeatureProtocol encapsulates the ability to read and write a FeatureCollection to java input/output streams. The writing of Features and FeatureTypes is done in an implementation independent manner.
The protocol uses two files, one to store FeatureTypes and associated ObjectStream Class related information, henceforth refered to as the "schema file". The second file is used to store Feature records themselves, henceforth refered to as the "feature file".
This technique allows random access to Features by tricking the ObjectInputStream and allowing it to "share" Class definitions during the reading process.
The format for the schema file is:

   magic "0xdeca"
   byte version
   Class FeaturePickler
   (byte 1, FeaturePickler)*
   byte 0
   short numberOfclasses
   Class*
 

The format for the feature file is:

   magic "0xdeca"
   byte version
   short numberOfFeatures
   (FeaturePicklerEntry)*
 

Where FeaturePickler is the actual object and a FeaturePicklerEntry is the record written by the FeaturePickler (representing a pickled Feature).

 NOTES:
  - should be rewritten as subclass of ObjectOutputStream/InputStream.
    + two stream constructors (types + features)
    + override writeObject to intercept classes
    + add writeCollection method which follows the logic of this...
 

Author:

Ian Schneider

Field Summary

static int

CURRENT_VERSION

Constructor Summary

PickledFeatureProtocol()

Method Summary

abstract void	close()
static PickledFeatureProtocol	getReader(java.io.InputStream fin, java.io.InputStream sin)
static PickledFeatureProtocol	getWriter(int version, java.io.OutputStream fout, java.io.OutputStream sout)
static PickledFeatureProtocol	getWriter(java.io.OutputStream fout, java.io.OutputStream sout)
protected abstract void	initRead(java.io.InputStream fin, java.io.InputStream sin)
protected abstract void	initWrite(java.io.OutputStream fout, java.io.OutputStream sout)
abstract void	read(FeatureCollection fc)
abstract Feature	read(int idx)
protected abstract int	version()
abstract void	write(FeatureCollection fc)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

CURRENT_VERSION

public static final int CURRENT_VERSION

See Also:

Constant Field Values

Constructor Detail

PickledFeatureProtocol

public PickledFeatureProtocol()

Method Detail

getReader

public static PickledFeatureProtocol getReader(java.io.InputStream fin,
                                               java.io.InputStream sin)
                                        throws java.io.IOException

Throws:

java.io.IOException

getWriter

public static PickledFeatureProtocol getWriter(java.io.OutputStream fout,
                                               java.io.OutputStream sout)
                                        throws java.io.IOException

Throws:

java.io.IOException

getWriter

public static PickledFeatureProtocol getWriter(int version,
                                               java.io.OutputStream fout,
                                               java.io.OutputStream sout)
                                        throws java.io.IOException

Throws:

java.io.IOException

initRead

protected abstract void initRead(java.io.InputStream fin,
                                 java.io.InputStream sin)
                          throws java.io.IOException

Throws:

java.io.IOException

initWrite

protected abstract void initWrite(java.io.OutputStream fout,
                                  java.io.OutputStream sout)
                           throws java.io.IOException

Throws:

java.io.IOException

version

protected abstract int version()

read

public abstract void read(FeatureCollection fc)
                   throws java.io.IOException,
                          java.lang.ClassNotFoundException,
                          SchemaException

Throws:

java.io.IOException

java.lang.ClassNotFoundException

SchemaException

read

public abstract Feature read(int idx)
                      throws java.io.IOException,
                             java.lang.ClassNotFoundException,
                             SchemaException

Throws:

java.io.IOException

java.lang.ClassNotFoundException

SchemaException

write

public abstract void write(FeatureCollection fc)
                    throws java.io.IOException

Throws:

java.io.IOException

close

public abstract void close()
                    throws java.io.IOException

Throws:

java.io.IOException