Package uk.ac.starlink.fits

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
    public class FitsTableBuilder
extends uk.ac.starlink.table.formats.DocumentedTableBuilder
implements uk.ac.starlink.table.MultiTableBuilder
    Implementation of the TableBuilder interface which gets StarTables 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)

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static uk.ac.starlink.table.StarTable attemptReadTable​(nom.tam.util.ArrayDataInput strm, boolean wantRandom, uk.ac.starlink.util.DataSource datsrc, WideFits wide, long[] pos)
      Reads the next header, and returns a StarTable based on it if it represents a table.
      boolean canImport​(java.awt.datatransfer.DataFlavor flavor)
      Returns true for a flavor with the MIME type "application/fits".
      boolean canStream()  
      boolean docIncludesExample()  
      static uk.ac.starlink.table.StarTable findNamedTable​(nom.tam.util.ArrayDataInput strm, uk.ac.starlink.util.DataSource datsrc, java.lang.String name, WideFits wide, long[] pos)
      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.
      java.lang.String getFormatName()
      Returns "FITS".
      java.lang.String getXmlDescription()  
      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​(java.io.InputStream istrm, uk.ac.starlink.table.TableSink sink, java.lang.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 Detail

      • FitsTableBuilder

        public FitsTableBuilder()
        Default constructor.

      • FitsTableBuilder

        public FitsTableBuilder​(WideFits wide)
        Constructor.
        Parameters:
        wide - convention for representing extended columns; use null to avoid use of extended columns

    • Method Detail

      • getFormatName

        public java.lang.String getFormatName()
        Returns "FITS".
        Specified by:
        getFormatName in interface uk.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 java.io.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 interface uk.ac.starlink.table.TableBuilder
        Parameters:
        datsrc - the source of the FITS table data
        wantRandom - whether a random-access table is preferred
        policy - a StoragePolicy object which may be used to supply scratch storage if the builder needs it
        Returns:
        a new StarTable based on datsrc, or null if it doesn't look like a FITS table
        Throws:
        java.io.IOException

      • makeStarTables

        public uk.ac.starlink.table.TableSequence makeStarTables​(uk.ac.starlink.util.DataSource datsrc,
                                                         uk.ac.starlink.table.StoragePolicy policy)
                                                  throws java.io.IOException
        Specified by:
        makeStarTables in interface uk.ac.starlink.table.MultiTableBuilder
        Throws:
        java.io.IOException

      • canImport

        public boolean canImport​(java.awt.datatransfer.DataFlavor flavor)
        Returns true for a flavor with the MIME type "application/fits".
        Specified by:
        canImport in interface uk.ac.starlink.table.TableBuilder

      • streamStarTable

        public void streamStarTable​(java.io.InputStream istrm,
                            uk.ac.starlink.table.TableSink sink,
                            java.lang.String extnum)
                     throws java.io.IOException
        Reads a FITS table from an input stream and writes it to a sink.
        Specified by:
        streamStarTable in interface uk.ac.starlink.table.TableBuilder
        Parameters:
        istrm - input stream containing the FITS data
        sink - destination for table data
        extnum - 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:
        java.io.IOException

      • canStream

        public boolean canStream()
        Specified by:
        canStream in class uk.ac.starlink.table.formats.DocumentedTableBuilder

      • docIncludesExample

        public boolean docIncludesExample()
        Specified by:
        docIncludesExample in interface uk.ac.starlink.table.formats.DocumentedIOHandler

      • getXmlDescription

        public java.lang.String getXmlDescription()
        Specified by:
        getXmlDescription in interface uk.ac.starlink.table.Documented

      • findNamedTable

        public static uk.ac.starlink.table.StarTable findNamedTable​(nom.tam.util.ArrayDataInput strm,
                                                            uk.ac.starlink.util.DataSource datsrc,
                                                            java.lang.String name,
                                                            WideFits wide,
                                                            long[] pos)
                                                     throws nom.tam.fits.FitsException,
                                                            java.io.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 supplied name 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:
        strm - stream to read from, positioned at the start of an HDU (before the header)
        datsrc - a DataSource which can supply the data in strm
        name - target extension name or name-version
        wide - convention for representing extended columns; use null to avoid use of extended columns
        pos - a 1-element array holding the position in datsrc at which strm is positioned - it's an array so it can be updated by this routine (sorry)
        Returns:
        a new table
        Throws:
        nom.tam.fits.FitsException
        java.io.IOException

      • attemptReadTable

        public static uk.ac.starlink.table.StarTable attemptReadTable​(nom.tam.util.ArrayDataInput strm,
                                                              boolean wantRandom,
                                                              uk.ac.starlink.util.DataSource datsrc,
                                                              WideFits wide,
                                                              long[] pos)
                                                       throws nom.tam.fits.FitsException,
                                                              java.io.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:
        strm - stream to read from, positioned at the start of an HDU (before the header)
        wantRandom - whether a random-access table is preferred
        datsrc - a DataSource which can supply the data in strm
        wide - convention for representing extended columns; use null to avoid use of extended columns
        pos - a 1-element array holding the position in datsrc at which strm is positioned - it's an array so it can be updated by this routine (sorry)
        Returns:
        a StarTable made from the HDU at the start of strm or null
        Throws:
        nom.tam.fits.FitsException
        java.io.IOException