uk.ac.starlink.table
Interface TableBuilder

All Known Implementing Classes:
AsciiTableBuilder, CsvTableBuilder, FitsPlusTableBuilder, FitsTableBuilder, IpacTableBuilder, VOTableBuilder, WDCTableBuilder

public interface TableBuilder

Interface for objects which can construct a StarTable from a data resource.


Method Summary
 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.
 StarTable makeStarTable(DataSource datsrc, boolean wantRandom, StoragePolicy storagePolicy)
          Constructs a StarTable based on a given DataSource.
 void streamStarTable(InputStream istrm, TableSink sink, String pos)
          Reads a table from an input stream and writes it a row at a time to a sink.
 

Method Detail

makeStarTable

public StarTable makeStarTable(DataSource datsrc,
                               boolean wantRandom,
                               StoragePolicy storagePolicy)
                        throws IOException
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.

Parameters:
datsrc - the DataSource containing the table resource
wantRandom - whether, preferentially, a random access table should be returned
storagePolicy - 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

streamStarTable

public void streamStarTable(InputStream istrm,
                            TableSink sink,
                            String pos)
                     throws IOException
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.

Parameters:
istrm - 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
IOException - if some other error occurs

canImport

public boolean canImport(DataFlavor flavor)
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 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[])).

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

getFormatName

public String getFormatName()
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.

Returns:
one-word description of this handler's format

Copyright © 2004 CLRC: Central Laboratory of the Research Councils. All rights reserved.