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java.lang.Objectuk.ac.starlink.votable.FitsPlusTableBuilder
Table builder which can read files in 'fits-plus' format (as written
by FitsPlusTableWriter
). This looks for a primary header
in the FITS file which contains the VOTMETA header (in fact it is
quite inflexible about what it recognises as this format -
see isMagic(byte[])
) and tries to interpret the data array as a
1-d array of bytes representing the XML of a VOTable document.
This VOTable document should have one TABLE element with no DATA
content - the table data is got from the first extension HDU,
which must be a BINTABLE extension matching the metadata described
by the VOTable.
The point of all this is so that you can store a VOTable in the efficient FITS format (it can be mapped if it's on local disk, which makes table creation practically instantaneous, even for random access) without sacrificing any of the metadata that you want to encode in VOTable format.
FitsPlusTableWriter
Constructor Summary | |
FitsPlusTableBuilder()
|
Method Summary | |
boolean |
canImport(DataFlavor flavor)
Returns true for a flavor with the MIME type "application/fits". |
String |
getFormatName()
Returns the name of the format which can be read by this handler. |
static boolean |
isMagic(byte[] buffer)
Tests whether a given buffer contains bytes which might be the first few bytes of a FitsPlus table. |
StarTable |
makeStarTable(DataSource datsrc,
boolean wantRandom,
StoragePolicy storagePolicy)
Constructs a StarTable based on a given DataSource. |
void |
streamStarTable(InputStream in,
TableSink sink,
String pos)
Reads a table from an input stream and writes it a row at a time to a sink. |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
public FitsPlusTableBuilder()
Method Detail |
public String getFormatName()
TableBuilder
getFormatName
in interface TableBuilder
public StarTable makeStarTable(DataSource datsrc, boolean wantRandom, StoragePolicy storagePolicy) throws IOException
TableBuilder
StarTable
based on a given DataSource.
If the source is not recognised or this builder does not know
how to construct a table from it, then a
TableFormatException
should be thrown.
If this builder thinks it should be able to handle the source
but an error occurs during processing, an IOException
can be thrown.
The wantRandom parameter is used to indicate whether, ideally, a random-access table should be returned. There is no requirement for the builder to honour this request, but if it knows how to make both random and non-random tables, it can use this flag to decide which to return.
makeStarTable
in interface TableBuilder
datsrc
- the DataSource containing the table resourcewantRandom
- whether, preferentially, a random access table
should be returnedstoragePolicy
- a StoragePolicy object which may be used to
supply scratch storage if the builder needs it
IOException
- if an unexpected I/O error occurs during processingpublic void streamStarTable(InputStream in, TableSink sink, String pos) throws IOException
TableBuilder
TableFormatException
.
The input stream should be prepared for use prior to calling this method, so implementations should not in general attempt to decompress or buffer istrm.
streamStarTable
in interface TableBuilder
in
- input stream containing table datasink
- destination of the tablepos
- position identifier describing the location of the
table within the stream;
see DataSource.getPosition()
(may be null)
IOException
- if some other error occurspublic boolean canImport(DataFlavor flavor)
canImport
in interface TableBuilder
flavor
- the DataFlavor whose suitability as stream input
is to be assessed
public static boolean isMagic(byte[] buffer)
SIMPLE = T BITPIX = 8 NAXIS = 1 NAXIS1 = ??? VOTMETA = T
buffer
- byte buffer containing leading few bytes of data
|
Copyright © 2004 CLRC: Central Laboratory of the Research Councils. All rights reserved. | |||||||||
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