gov.nasa.pds.label.object

Class DataObject

java.lang.Object

gov.nasa.pds.label.object.DataObject

Direct Known Subclasses:

ArrayObject, GenericObject, TableObject

public abstract class DataObject
extends java.lang.Object

Defines a base type for objects within a label.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	DataObject(java.io.File parentDir, File fileObject, long offset, long size)
protected	DataObject(java.net.URL parentDir, File fileObject, long offset, long size)

Method Summary

Modifier and Type	Method and Description
void	closeChannel() Closes the underlying channel to the data.
java.nio.channels.SeekableByteChannel	getChannel() Gets a SeekableByteChannel for accessing the data object.
java.net.URL	getDataFile() Gets a url that refers to the data file for this object.
java.io.InputStream	getInputStream() Gets an input stream to the data object.
long	getOffset() Gets the offset within the data file where the object data begins.
long	getSize() Gets the size of the data object within the data file.
protected void	setSize(long newSize)

Methods inherited from class java.lang.Object

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

Constructor Detail

DataObject

protected DataObject(java.io.File parentDir,
                     File fileObject,
                     long offset,
                     long size)
              throws java.io.IOException

Throws:

java.io.IOException

DataObject

protected DataObject(java.net.URL parentDir,
                     File fileObject,
                     long offset,
                     long size)
              throws java.io.IOException

Throws:

java.io.IOException

Method Detail

getDataFile

public java.net.URL getDataFile()
                         throws java.net.MalformedURLException

Gets a url that refers to the data file for this object.

Returns:

a URL for the file containing the data object

Throws:

java.net.MalformedURLException

getOffset

public long getOffset()

Gets the offset within the data file where the object data begins.

Returns:

the offset to the data

getSize

public long getSize()

Gets the size of the data object within the data file.

Returns:

the size of the data object, in bytes

setSize

protected void setSize(long newSize)

getInputStream

public java.io.InputStream getInputStream()
                                   throws java.io.IOException

Gets an input stream to the data object. This input stream will read from the first byte in the data object to the last byte within that object. Other bytes outside of the range for the data object will not be accessed.

Returns:

an input stream to the data object

Throws:

java.io.FileNotFoundException - if the data file cannot be found

java.io.IOException - if there is an error reading the data file

getChannel

public java.nio.channels.SeekableByteChannel getChannel()
                                                 throws java.io.IOException

Gets a SeekableByteChannel for accessing the data object. The channel is read-only, and represents only the portion of the data file containing the data object. You must remember to call the closeChannel() method once reading of the data is finished.

Returns:

a SeekableByteChannel for reading bytes from the data object

Throws:

java.io.IOException - if there is an error reading the data file

closeChannel

public void closeChannel()

Closes the underlying channel to the data.