uk.ac.starlink.util

Class FileDataSource

java.lang.Object

uk.ac.starlink.util.DataSource

uk.ac.starlink.util.FileDataSource

Direct Known Subclasses:

TemporaryFileDataSource

public class FileDataSource
extends DataSource

A DataSource implementation based on a File.

Author:

Mark Taylor (Starlink)

Field Summary

Fields inherited from class uk.ac.starlink.util.DataSource

DEFAULT_INTRO_LIMIT, MARK_WORKAROUND_PROPERTY

Constructor Summary

Constructors

Constructor and Description
FileDataSource(File file) Creates a new FileDataSource from a File object.
FileDataSource(File file, String position) Creates a new FileDataSource from a File object and a position string.
FileDataSource(String filename) Creates a new FileDataSource from a filename.

Method Summary

Modifier and Type	Method and Description
File	getFile() Returns the File object on which this FileDataSource is based.
protected InputStream	getRawInputStream() Provides a new InputStream for this data source.
long	getRawLength() Returns the length of this file.
URL	getURL() Returns a URL which corresponds to this data source, if one exists.

Methods inherited from class uk.ac.starlink.util.DataSource

close, forceCompression, getCompression, getHybridInputStream, getInputStream, getInputStream, getIntro, getIntroLimit, getLength, getMarkWorkaround, getName, getPosition, getSystemId, makeDataSource, makeDataSource, makeDataSource, setCompression, setIntroLimit, setMarkWorkaround, setName, setPosition, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

FileDataSource

public FileDataSource(File file,
                      String position)
               throws IOException

Creates a new FileDataSource from a File object and a position string.

Parameters:

file - the file

position - the source's position attribute (indicates the relevant part of the file)

Throws:

IOException - if file does not exist, cannot be read, or is a directory

FileDataSource

public FileDataSource(File file)
               throws IOException

Creates a new FileDataSource from a File object.

Parameters:

file - the file

Throws:

IOException - if file does not exist, cannot be read, or is a directory

FileDataSource

public FileDataSource(String filename)
               throws IOException

Creates a new FileDataSource from a filename.

Parameters:

filename - filename

Throws:

IOException - if filename does not name a readable file

Method Detail

getRawInputStream

protected InputStream getRawInputStream()
                                 throws IOException

Description copied from class: DataSource

Provides a new InputStream for this data source. This method should be implemented by subclasses to provide a new InputStream giving the raw content of the source each time it is called. The general contract of this method is that each time it is called it will return a stream with the same content.

Specified by:

getRawInputStream in class DataSource

Returns:

an InputStream containing the data of this source

Throws:

IOException

getRawLength

public long getRawLength()

Returns the length of this file. return file length

Overrides:

getRawLength in class DataSource

Returns:

the length of the raw input stream, or -1

getFile

public File getFile()

Returns the File object on which this FileDataSource is based.

Returns:

the file

getURL

public URL getURL()

Description copied from class: DataSource

Returns a URL which corresponds to this data source, if one exists. An URL.openConnection() method call on the URL returned by this method should provide a stream with the same content as the DataSource.getRawInputStream() method of this data source. If no such URL exists or is known, then null should be returned.

If this source has a non-null position value, it will be appended to the main part of the URL after a '#' character (as the URL's ref part).

Overrides:

getURL in class DataSource

Returns:

a URL corresponding to this source, or null