Class FitsTableBuilder
- All Implemented Interfaces:
uk.ac.starlink.table.Documented
,uk.ac.starlink.table.formats.DocumentedIOHandler
,uk.ac.starlink.table.MultiTableBuilder
,uk.ac.starlink.table.TableBuilder
TableBuilder
interface which
gets StarTable
s from FITS files.
The table implementation used by uncompressed binary FITS tables
stored on disk maps the file into memory
(MappedByteBuffer
) rather than reading the stream as such;
this makes table construction very fast and cheap on memory, regardless of
storage policy. This behaviour can be inhibited by referring to the
file location as a URL (e.g. "file:spec23.fits" rather than "spec23.fits"),
which fools the handler into thinking that it can't be mapped.
Limited support is provided for the
HEALPix-FITS convention;
the relevant HealpixTableInfo
table parameters
are added, but any BAD_DATA keyword value is ignored,
and the 1024-element array-valued column variant of the format is not
understood.
- Author:
- Mark Taylor (Starlink)
-
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionstatic uk.ac.starlink.table.StarTable
attemptReadTable
(InputStream in, boolean wantRandom, uk.ac.starlink.util.DataSource datsrc, WideFits wide, long[] pos, uk.ac.starlink.table.StoragePolicy policy) Reads the next header, and returns a StarTable based on it if it represents a table.boolean
canImport
(DataFlavor flavor) Returnstrue
for a flavor with the MIME type "application/fits".boolean
boolean
static uk.ac.starlink.table.StarTable
findNamedTable
(InputStream in, uk.ac.starlink.util.DataSource datsrc, String name, WideFits wide, long[] pos, uk.ac.starlink.table.StoragePolicy policy) Looks through the HDUs in a given FITS stream and if it finds one which has a given name, attempts to make a table out of it.Returns "FITS".uk.ac.starlink.table.StarTable
makeStarTable
(uk.ac.starlink.util.DataSource datsrc, boolean wantRandom, uk.ac.starlink.table.StoragePolicy policy) Creates a StarTable from a DataSource which refers to a FITS file or stream.uk.ac.starlink.table.TableSequence
makeStarTables
(uk.ac.starlink.util.DataSource datsrc, uk.ac.starlink.table.StoragePolicy policy) void
streamStarTable
(InputStream in, uk.ac.starlink.table.TableSink sink, String extnum) Reads a FITS table from an input stream and writes it to a sink.Methods inherited from class uk.ac.starlink.table.formats.DocumentedTableBuilder
getExtensions, looksLikeFile
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface uk.ac.starlink.table.formats.DocumentedIOHandler
readText
Methods inherited from interface uk.ac.starlink.table.TableBuilder
looksLikeFile
-
Constructor Details
-
FitsTableBuilder
public FitsTableBuilder()Default constructor. -
FitsTableBuilder
Constructor.- Parameters:
wide
- convention for representing extended columns; use null to avoid use of extended columns
-
-
Method Details
-
getFormatName
Returns "FITS".- Specified by:
getFormatName
in interfaceuk.ac.starlink.table.TableBuilder
-
makeStarTable
public uk.ac.starlink.table.StarTable makeStarTable(uk.ac.starlink.util.DataSource datsrc, boolean wantRandom, uk.ac.starlink.table.StoragePolicy policy) throws IOException Creates a StarTable from a DataSource which refers to a FITS file or stream. If the source has a position attribute, it will be interpreted in one of two ways:- If it's an integer, it will be interpreted as the index of the HDU holding the table. The first HDU is number 0 (though being primary this one can't hold a table), the first extension is number 1, etc.
- Otherwise it's interpreted as the name of the extension. Either of the forms "EXTNAME" or "EXTNAME-EXTVER" is permitted, where EXTNAME and EXTVER are the values of the corresponding FITS header cards, as per the FITS standard.
If the EXTNAME happens to be in the form of a positive integer, this means you can't refer to the extension by name. Too bad.
If there is no position attribute, the first HDU which does hold a table is used.
- Specified by:
makeStarTable
in interfaceuk.ac.starlink.table.TableBuilder
- Parameters:
datsrc
- the source of the FITS table datawantRandom
- whether a random-access table is preferredpolicy
- a StoragePolicy object which may be used to supply scratch storage if the builder needs it- Returns:
- a new StarTable based on
datsrc
, ornull
if it doesn't look like a FITS table - Throws:
IOException
-
makeStarTables
public uk.ac.starlink.table.TableSequence makeStarTables(uk.ac.starlink.util.DataSource datsrc, uk.ac.starlink.table.StoragePolicy policy) throws IOException - Specified by:
makeStarTables
in interfaceuk.ac.starlink.table.MultiTableBuilder
- Throws:
IOException
-
canImport
Returnstrue
for a flavor with the MIME type "application/fits".- Specified by:
canImport
in interfaceuk.ac.starlink.table.TableBuilder
-
streamStarTable
public void streamStarTable(InputStream in, uk.ac.starlink.table.TableSink sink, String extnum) throws IOException Reads a FITS table from an input stream and writes it to a sink.- Specified by:
streamStarTable
in interfaceuk.ac.starlink.table.TableBuilder
- Parameters:
in
- input stream containing the FITS datasink
- destination for table dataextnum
- may contain a string representation of the HDU number in which the required table is found (otherwise the first table HDU will be used)- Throws:
IOException
-
canStream
public boolean canStream()- Specified by:
canStream
in classuk.ac.starlink.table.formats.DocumentedTableBuilder
-
docIncludesExample
public boolean docIncludesExample()- Specified by:
docIncludesExample
in interfaceuk.ac.starlink.table.formats.DocumentedIOHandler
-
getXmlDescription
- Specified by:
getXmlDescription
in interfaceuk.ac.starlink.table.Documented
-
findNamedTable
public static uk.ac.starlink.table.StarTable findNamedTable(InputStream in, uk.ac.starlink.util.DataSource datsrc, String name, WideFits wide, long[] pos, uk.ac.starlink.table.StoragePolicy policy) throws IOException Looks through the HDUs in a given FITS stream and if it finds one which has a given name, attempts to make a table out of it. The suppliedname
is checked against the EXTNAME header value (if present), and if that fails, against EXTNAME-EXTVER (if EXTVER is present too). Matching is case-insensitive.- Parameters:
in
- stream to read from, positioned at the start of an HDU (before the header)datsrc
- a DataSource which can supply the data instrm
name
- target extension name or name-versionwide
- convention for representing extended columns; use null to avoid use of extended columnspos
- a 1-element array holding the position indatsrc
at whichstrm
is positioned - it's an array so it can be updated by this routine (sorry)policy
- storage policy, or null for default (normally not used)- Returns:
- a new table
- Throws:
IOException
-
attemptReadTable
public static uk.ac.starlink.table.StarTable attemptReadTable(InputStream in, boolean wantRandom, uk.ac.starlink.util.DataSource datsrc, WideFits wide, long[] pos, uk.ac.starlink.table.StoragePolicy policy) throws IOException Reads the next header, and returns a StarTable based on it if it represents a table. If a StarTable is returned, it may not be safe to use the supplied input stream subsequently for other purposes. If the next HDU is some non-table type,null
is returned and the stream is advanced to the end of that HDU; in this case the stream may continue to be used (e.g. for further calls to this method).On exit, the first element of the
pos
array contains the position after the current HDU.- Parameters:
in
- stream to read from, positioned at the start of an HDU (before the header)wantRandom
- whether a random-access table is preferreddatsrc
- a DataSource which can supply the data instrm
wide
- convention for representing extended columns; use null to avoid use of extended columnspos
- a 1-element array holding the position indatsrc
at whichstrm
is positioned - it's an array so it can be updated by this routine (sorry)policy
- storage policy, or null for default (normally not used)- Returns:
- a StarTable made from the HDU at the start of
strm
or null - Throws:
IOException
-