Package uk.ac.starlink.fits

Class FitsTableBuilder

java.lang.Object
uk.ac.starlink.table.formats.DocumentedTableBuilder
uk.ac.starlink.fits.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)

  • Constructor Summary

    Constructors
    Constructor
    Description
    FitsTableBuilder()
    Default constructor.
    FitsTableBuilder(WideFits wide)
    Constructor.

  • Method Summary

    Modifier and Type
    Method
    Description
    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)
    Reads the next header, and returns a StarTable based on it if it represents a table.
    boolean
    canImport(DataFlavor flavor)
    Returns true for a flavor with the MIME type "application/fits".
    boolean
    canStream()
     
    boolean
    docIncludesExample()
     
    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.
    String
    getFormatName()
    Returns "FITS".
    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(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

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

  • Method Details

    • getFormatName

      public 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 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:
      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 interface uk.ac.starlink.table.MultiTableBuilder
      Throws:
      IOException

    • canImport

      public boolean canImport(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(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 interface uk.ac.starlink.table.TableBuilder
      Parameters:
      in - 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:
      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 String getXmlDescription()
      Specified by:
      getXmlDescription in interface uk.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 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:
      in - 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)
      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 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)
      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