ColFitsPlusTableBuilder (Starlink-UK API)

java.lang.Object
- uk.ac.starlink.votable.ColFitsPlusTableBuilder

All Implemented Interfaces:

TableBuilder
```
public class ColFitsPlusTableBuilder
extends Object
implements TableBuilder
```
Implementation of the TableBuilder interface which reads tables stored in column-oriented FITS binary table format. The table data is stored in a BINTABLE extension which has a single row; each cell in this row contains the data for an entire column of the represented table. The primary HDU contains a byte[] array giving the table metadata as a VOTable, as for FitsPlusTableBuilder. If the VOTMETA card in the primary HDU does not have the value T, the VOTable metadata array is ignored.
This rather specialised format may provide good performance for certain operations on very large, especially very wide, tables. Although it is FITS and can therefore be used in principle for data interchange, in practice most non-STIL processors are unlikely to be able to do much useful with it.

Since:

26 Jun 2006

Author:

Mark Taylor

Constructor Summary

Constructors
Constructor and Description

ColFitsPlusTableBuilder()
Default constructor.

ColFitsPlusTableBuilder(WideFits wide)
Constructor.

Constructors
Constructor and Description
`ColFitsPlusTableBuilder()` Default constructor.
`ColFitsPlusTableBuilder(WideFits wide)` Constructor.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`canImport(DataFlavor flavor)` Indicates whether this builder is able to turn a resource of media type indicated by `flavor` into a table.
`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.
`boolean`	`looksLikeFile(String location)` Indicates whether the given location string is of a familiar form for this builder.
`StarTable`	`makeStarTable(DataSource datsrc, boolean wantRandom, StoragePolicy policy)` 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
  - ColFitsPlusTableBuilder
```
public ColFitsPlusTableBuilder()
```
    Default constructor.
  - ColFitsPlusTableBuilder
```
public ColFitsPlusTableBuilder(WideFits wide)
```
    Constructor.
    
    Parameters:
    
    wide - convention for representing extended columns; use null to avoid use of extended columns
- Method Detail
  - getFormatName
```
public String getFormatName()
```
    Description copied from interface: TableBuilder
    
    Returns the name of the format which can be read by this handler. Matching against this string may be used by callers to identify or select this handler from a list.
    
    Specified by:
    
    getFormatName in interface TableBuilder
    
    Returns:
    
    one-word description of this handler's format
  - looksLikeFile
```
public boolean looksLikeFile(String location)
```
    Description copied from interface: TableBuilder
    
    Indicates whether the given location string is of a familiar form for this builder. Implementations should return true if there is a good chance that a file with the given location can be interpreted by this reader, for instance if it has a suitable file extension.
    This method may be used to guess, on a best-efforts basis, whether this builder is suitable for reading a file from a given location. Attempts may still be made to read inputs for which this method returns false. It is less important for builders that can recognise files by magic number, which is generally preferable to using filenames.
    
    Specified by:
    
    looksLikeFile in interface TableBuilder
    
    Parameters:
    
    location - the location string, such as a filename or URL (not null)
    
    Returns:
    
    true iff there is a good chance that the named input can be interpreted by this reader
  - streamStarTable
```
public void streamStarTable(InputStream in,
                            TableSink sink,
                            String pos)
                     throws TableFormatException
```
    Description copied from interface: TableBuilder
    
    Reads a table from an input stream and writes it a row at a time to a sink. Not all implementations will be able to do this; for instance, extracting the table from the data may be a two-pass process. Implementations which are unable to perform this function should throw a 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.
    
    Specified by:
    
    streamStarTable in interface TableBuilder
    
    Parameters:
    
    in - input stream containing table data
    
    sink - destination of the table
    
    pos - position identifier describing the location of the table within the stream; see DataSource.getPosition() (may be null)
    
    Throws:
    
    TableFormatException - if the table can't be streamed or the data is malformed
  - canImport
```
public boolean canImport(DataFlavor flavor)
```
    Description copied from interface: TableBuilder
    
    Indicates whether this builder is able to turn a resource of media type indicated by flavor into a table. It should return true if it thinks that its TableBuilder.streamStarTable(java.io.InputStream, uk.ac.starlink.table.TableSink, java.lang.String) method stands a reasonable chance of successfully constructing a StarTable from a DataSource whose input stream is described by the DataFlavor flavor. It will typically make this determination based on the flavor's MIME type.
    This method should only return true if the flavor looks like it is targeted at this builder; for instance a builder which uses a text-based format should return false for a flavor which indicates a MIME type of text/plain.
    This method is used in supporting drag and drop functionality (see StarTableFactory.canImport(java.awt.datatransfer.DataFlavor[])).
    
    Specified by:
    
    canImport in interface TableBuilder
    
    Parameters:
    
    flavor - the DataFlavor whose suitability as stream input is to be assessed
    
    Returns:
    
    true iff this builder reckons it stands a good chance of turning a stream of type flavor into a StarTable
  - makeStarTable
```
public StarTable makeStarTable(DataSource datsrc,
                               boolean wantRandom,
                               StoragePolicy policy)
                        throws IOException
```
    Description copied from interface: TableBuilder
    
    Constructs a 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.
    Note: the presence of the wantRandom parameter is somewhat misleading. TableBuilder implementations usually should, and do, ignore it (it would be removed from the interface if it were not for backward compatibility issues). Regardless of the value of this parameter, implementations should return a random-access table only if it is easy for them to do so; in particular they should not use the supplied storagePolicy, or any other resource-expensive measure, to randomise a sequential table just because the wantRandom parameter is true.
    
    Specified by:
    
    makeStarTable in interface TableBuilder
    
    Parameters:
    
    datsrc - the DataSource containing the table resource
    
    wantRandom - whether, preferentially, a random access table should be returned
    
    policy - a StoragePolicy object which may be used to supply scratch storage if the builder needs it
    
    Returns:
    
    a StarTable made out of datsrc
    
    Throws:
    
    TableFormatException - if the table is not of a kind that can be handled by this handler
    
    IOException - if an unexpected I/O error occurs during processing
  - isMagic
```
public static boolean isMagic(byte[] buffer)
```
    Tests whether a given buffer contains bytes which might be the first few bytes of a FitsPlus table. The criterion is that it looks like the start of a FITS header, and the first few cards look roughly like this:
```
     SIMPLE  =              T
     BITPIX  =              8
     NAXIS   =              1
     NAXIS1  =            ???
     COLFITS =              T
     VOTMETA =              T
 
```
    Parameters:
    
    buffer - byte buffer containing leading few bytes of data
    
    Returns:
    
    true if it looks like a FitsPlus file

Class ColFitsPlusTableBuilder

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

ColFitsPlusTableBuilder

ColFitsPlusTableBuilder

Method Detail

getFormatName

looksLikeFile

streamStarTable

canImport

makeStarTable

isMagic