uk.ac.starlink.table

Class StarTableOutput

java.lang.Object

uk.ac.starlink.table.StarTableOutput

public class StarTableOutput
extends Object

Outputs StarTable objects. This object delegates the actual writing to one of a list of format-specific writer objects whose content can be configured externally. By default, if the corresponding classes are present, the following handlers are installed:

• UnifiedFitsTableWriter
• VOTableWriter
• HealpixFitsTableWriter
• EcsvTableWriter
• ParquetTableWriter
• TextTableWriter
• AsciiTableWriter
• CsvTableWriter
• IpacTableWriter
• HTMLTableWriter
• LatexTableWriter
• TstTableWriter
• FeatherTableWriter
• MirageTableWriter

Additionally, any classes named in the startable.writers system property (as a colon-separated list) which implement the StarTableWriter interface and have a no-arg constructor will be instantiated and added to this list of handlers.

It can additionally write to JDBC tables.

Author:

Mark Taylor (Starlink)

Field Summary

Fields

Modifier and Type	Field and Description
static String	AUTO_HANDLER Special output handler name indicating automatic format selection.
static String	EXTRA_WRITERS_PROPERTY System property which can contain a list of StarTableWriter classes for addition to the list of known output handlers.

Constructor Summary

Constructors

Constructor and Description
StarTableOutput() Constructs a StarTableOutput with a default list of handlers.

Method Summary

Modifier and Type	Method and Description
TableSink	createOutputSink(OutputStream out, StarTableWriter handler) Returns a sink which allows you to write data to an output table.
TableSink	createOutputSink(String location, String format) Returns a sink which allows you to write data to an output table.
StarTableWriter	getHandler(String format) Returns a StarTableWriter object given an output format name.
StarTableWriter	getHandler(String format, String location) Returns a StarTableWriter object given an output format name and/or a location to write to.
List<StarTableWriter>	getHandlers() Gets the list of handlers which can actually do table output.
JDBCHandler	getJDBCHandler() Returns the JDBCHandler object used for writing tables to JDBC connections.
List<String>	getKnownFormats() Returns a list of the format strings which are defined by the handlers registered with this object.
OutputStream	getOutputStream(String location) Returns an output stream which points to a given location.
void	setHandlers(StarTableWriter[] handlers) Sets the list of handlers which can actually do table output.
void	setJDBCHandler(JDBCHandler handler) Sets the JDBCHandler object used for writing tables to JDBC connections.
Transferable	transferStarTable(StarTable startab) Returns a Transferable object associated with a given StarTable, for use at the drag end of a drag and drop operation.
void	writeStarTable(StarTable startab, OutputStream out, StarTableWriter handler) Writes a StarTable to an output stream.
void	writeStarTable(StarTable startab, String location, String format) Writes a StarTable object out to some external storage.
void	writeStarTables(StarTable[] tables, OutputStream out, MultiStarTableWriter handler) Writes an array of StarTables to an output stream.
void	writeStarTables(StarTable[] tables, String location, String format) Writes an array of StarTable objects to some external storage.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

AUTO_HANDLER

public static final String AUTO_HANDLER

Special output handler name indicating automatic format selection.

See Also:

Constant Field Values

EXTRA_WRITERS_PROPERTY

public static final String EXTRA_WRITERS_PROPERTY

System property which can contain a list of StarTableWriter classes for addition to the list of known output handlers.

See Also:

Constant Field Values

Constructor Detail

StarTableOutput

public StarTableOutput()

Constructs a StarTableOutput with a default list of handlers.

Method Detail

getHandlers

public List<StarTableWriter> getHandlers()

Gets the list of handlers which can actually do table output. Handlers earlier in the list are given a chance to write the table before ones later in the list. The returned list may be modified to change this object's behaviour.

Returns:

handlers a list of StarTableWriter objects

setHandlers

public void setHandlers(StarTableWriter[] handlers)

Sets the list of handlers which can actually do table output. Handlers earlier in the list are given a chance to write the table before ones later in the list.

Parameters:

handlers - an array of StarTableWriter objects

writeStarTable

public void writeStarTable(StarTable startab,
                           String location,
                           String format)
                    throws TableFormatException,
                           IOException

Writes a StarTable object out to some external storage. The format in which it is written is determined by some combination of the given output location and a format indicator.

Parameters:

startab - the table to output

location - the location at which to write the new table. This may be a filename or URL, including a jdbc: protocol if suitable JDBC drivers are installed

format - a string which indicates in some way what format should be used for output. This may be the class name of a StarTableWriter object (which may or may not be registered with this StarTableOutput), or else a string which matches the format name of one of the registered StarTableWriters (first match is used, case-insensitive, starting substrings OK) or null or AUTO_HANDLER to indicate that a handler should be selected based on the value of location. Ignored for jdbc:-protocol locations

Throws:

TableFormatException - if no suitable handler is known

IOException

writeStarTable

public void writeStarTable(StarTable startab,
                           OutputStream out,
                           StarTableWriter handler)
                    throws IOException

Writes a StarTable to an output stream. This convenience method wraps the stream in a BufferedOutputStream for efficiency and uses the submitted handler to perform the write, closing the stream afterwards.

Parameters:

startab - table to write

out - raw output stream

handler - output handler

Throws:

IOException

See Also:

getHandler(java.lang.String)

writeStarTables

public void writeStarTables(StarTable[] tables,
                            String location,
                            String format)
                     throws TableFormatException,
                            IOException

Writes an array of StarTable objects to some external storage. The format in which they are written is determined by some combination of the given output location and a format indicator. Note that not all registered output handlers are capable of writing multiple tables; an exception will be thrown if an attempt is made to write multiple tables with a handler which does not implement MultiStarTableWriter.

Parameters:

tables - the tables to output

location - the location at which to write the tables; this may be a filename or URL

format - a string which indicates in some way what format should be used for output. This may be the class name of a MultiStarTableWriter object (which may or may not be registered with this StarTableOutput), or else a string which matches the format name of one of the registered MultiStarTableWriters (first match is used, case-insensitive, starting substrings OK) or null or AUTO_HANDLER to indicate that a handler should be selected based on the value of location.

Throws:

TableFormatException

IOException

writeStarTables

public void writeStarTables(StarTable[] tables,
                            OutputStream out,
                            MultiStarTableWriter handler)
                     throws IOException

Writes an array of StarTables to an output stream. This convenience method wraps the stream in a BufferedOutputStream for efficiency and uses the submitted handler to perform the write, closing the stream afterwards.

Parameters:

tables - tables to write

out - destination stream

handler - output handler

Throws:

IOException

createOutputSink

public TableSink createOutputSink(OutputStream out,
                                  StarTableWriter handler)

Returns a sink which allows you to write data to an output table. Note that this will only work if the handler can write the table using a single pass of the data. If it requires multiple passes, a UnrepeatableSequenceException will be thrown.

Parameters:

out - raw output stream

handler - output handler

Returns:

sink whose data will be written to a new table

createOutputSink

public TableSink createOutputSink(String location,
                                  String format)

Returns a sink which allows you to write data to an output table. Note that this will only work if the handler can write the table using a single pass of the data. If it requires multiple passes, a UnrepeatableSequenceException will be thrown.

Parameters:

location - the location at which to write the new table. This may be a filename or URL, including a jdbc: protocol if suitable JDBC drivers are installed

format - a string which indicates in some way what format should be used for output. This may be the class name of a StarTableWriter object (which may or may not be registered with this StarTableOutput), or else a string which matches the format name of one of the registered StarTableWriters (first match is used, case-insensitive, starting substrings OK) or null or AUTO_HANDLER to indicate that a handler should be selected based on the value of location. Ignored for jdbc:-protocol locations

Returns:

sink whose data will be written to a new table

getOutputStream

public OutputStream getOutputStream(String location)
                             throws IOException

Returns an output stream which points to a given location. Typically location is a filename and a corresponding FileOutputStream is returned, but there may be other possibilities. The stream returned by this method will not in general be buffered; for high performance writes, wrapping it in a BufferedOutputStream may be a good idea.

Parameters:

location - name of destination

Returns:

output stream which writes to location

Throws:

IOException - if no stream pointing to location can be opened

getHandler

public StarTableWriter getHandler(String format)
                           throws TableFormatException

Returns a StarTableWriter object given an output format name.

Parameters:

format - a string which indicates in some way what format should be used for output. This may be the class name of a StarTableWriter object (which may or may not be registered with this StarTableOutput), or else a string which matches the format name of one of the registered StarTableWriters (first match is used, case-insensitive, starting substrings OK).

Returns:

a suitable output handler

Throws:

TableFormatException - if no handler suitable for the arguments can be found

getHandler

public StarTableWriter getHandler(String format,
                                  String location)
                           throws TableFormatException

Returns a StarTableWriter object given an output format name and/or a location to write to. If the format name is blank, the location is used to guess the type of output required.

Parameters:

format - a string which indicates in some way what format should be used for output. This may be the class name of a StarTableWriter object (which may or may not be registered with this StarTableOutput), or else a string which matches the format name of one of the registered StarTableWriters (first match is used, case-insensitive, starting substrings OK) or null to indicate that a handler should be selected based on the value of location.

location - destination of the table to be written. If format is null, the value of this will be used to try to determine which handler to use, typically on the basis of filename extension

Returns:

a suitable output handler

Throws:

TableFormatException - if no handler suitable for the arguments can be found

getKnownFormats

public List<String> getKnownFormats()

Returns a list of the format strings which are defined by the handlers registered with this object. The elements of the returned list can be passed as the format argument to the writeStarTable(uk.ac.starlink.table.StarTable, java.lang.String, java.lang.String) method.

getJDBCHandler

public JDBCHandler getJDBCHandler()

Returns the JDBCHandler object used for writing tables to JDBC connections.

Returns:

the JDBC handler

setJDBCHandler

public void setJDBCHandler(JDBCHandler handler)

Sets the JDBCHandler object used for writing tables to JDBC connections.

Parameters:

handler - the handler to use

transferStarTable

public Transferable transferStarTable(StarTable startab)

Returns a Transferable object associated with a given StarTable, for use at the drag end of a drag and drop operation.

Parameters:

startab - the table which is to be dragged

See Also:

StarTableFactory.makeStarTable(java.awt.datatransfer.Transferable)