Package org.eclipse.rdf4j.query.resultio.sparqljson

Class SPARQLResultsJSONWriter

java.lang.Object

org.eclipse.rdf4j.query.resultio.AbstractQueryResultWriter

org.eclipse.rdf4j.query.resultio.sparqljson.SPARQLResultsJSONWriter

All Implemented Interfaces:

CharSink, Sink, QueryResultHandler, QueryResultWriter, TupleQueryResultWriter, TupleQueryResultHandler

Direct Known Subclasses:

SPARQLStarResultsJSONWriter

public class SPARQLResultsJSONWriter
extends AbstractQueryResultWriter
implements TupleQueryResultWriter

A TupleQueryResultWriter that writes query results in the SPARQL Query Results JSON Format.

Field Summary

Fields

Modifier and Type	Field	Description
protected boolean	documentOpen
protected boolean	firstTupleWritten
protected boolean	headerComplete
protected boolean	headerOpen
protected final com.fasterxml.jackson.core.JsonGenerator	jg
protected boolean	linksFound
protected boolean	tupleVariablesFound

Constructor Summary

Constructors

Constructor	Description
SPARQLResultsJSONWriter(OutputStream out)
SPARQLResultsJSONWriter(Writer writer)

Method Summary

Modifier and Type	Method	Description
protected void	endDocument()
void	endHeader()	Indicates the end of the header.
void	endQueryResult()	Indicates the end of a sequence of solutions.
TupleQueryResultFormat	getQueryResultFormat()	Gets the query result format that this writer uses.
final Collection<RioSetting<?>>	getSupportedSettings()
TupleQueryResultFormat	getTupleQueryResultFormat()	Gets the query result format that this writer uses.
final Writer	getWriter()	get the Writer used by this CharSink.
void	handleBoolean(boolean value)	Handles the specified boolean value.
void	handleLinks(List<String> linkUrls)	Handles the links elements which are present in SPARQL Results JSON and SPARQL Results XML documents in the header.
void	handleNamespace(String prefix, String uri)	Handles a namespace prefix declaration.
protected void	handleSolutionImpl(BindingSet bindingSet)	Extending classes must implement this method instead of overriding AbstractQueryResultWriter.handleSolution(BindingSet) in order to benefit from automatic handling of RDF-star encoding.
void	handleStylesheet(String stylesheetUrl)	Handles a stylesheet URL.
void	startDocument()	Indicates the start of the document.
void	startHeader()	Indicates the start of the header.
void	startQueryResult(List<String> columnHeaders)	Indicates the start of a sequence of Solutions.
protected void	writeValue(Value value)

Methods inherited from class org.eclipse.rdf4j.query.resultio.AbstractQueryResultWriter

getFileFormat, getWriterConfig, handleSolution, setWriterConfig, xsdStringToPlainLiteral

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.eclipse.rdf4j.query.QueryResultHandler

endQueryResult, handleBoolean, handleLinks, handleSolution, startQueryResult

Methods inherited from interface org.eclipse.rdf4j.query.resultio.QueryResultWriter

endHeader, getSupportedSettings, getWriterConfig, handleNamespace, handleStylesheet, setWriterConfig, startDocument, startHeader

Methods inherited from interface org.eclipse.rdf4j.common.io.Sink

acceptsFileFormat, getFileFormat

Field Details

firstTupleWritten

protected boolean firstTupleWritten

documentOpen

protected boolean documentOpen

headerOpen

protected boolean headerOpen

headerComplete

protected boolean headerComplete

tupleVariablesFound

protected boolean tupleVariablesFound

linksFound

protected boolean linksFound

jg

protected final com.fasterxml.jackson.core.JsonGenerator jg

Constructor Details

SPARQLResultsJSONWriter

public SPARQLResultsJSONWriter(OutputStream out)

SPARQLResultsJSONWriter

public SPARQLResultsJSONWriter(Writer writer)

Method Details

getTupleQueryResultFormat

public TupleQueryResultFormat getTupleQueryResultFormat()

Description copied from interface: TupleQueryResultWriter

Gets the query result format that this writer uses.

Specified by:

getTupleQueryResultFormat in interface TupleQueryResultWriter

getQueryResultFormat

public TupleQueryResultFormat getQueryResultFormat()

Description copied from interface: QueryResultWriter

Gets the query result format that this writer uses.

Specified by:

getQueryResultFormat in interface QueryResultWriter

writeValue

protected void writeValue(Value value)
                   throws IOException,
QueryResultHandlerException

Throws:

IOException

QueryResultHandlerException

getWriter

public final Writer getWriter()

Description copied from interface: CharSink

get the Writer used by this CharSink.

Specified by:

getWriter in interface CharSink

Returns:

an Writer

endHeader

public void endHeader()
               throws QueryResultHandlerException

Description copied from interface: QueryResultWriter

Indicates the end of the header. This must be called after QueryResultWriter.startHeader() and before any calls to QueryResultHandler.handleSolution(org.eclipse.rdf4j.query.BindingSet).

Specified by:

endHeader in interface QueryResultWriter

Throws:

QueryResultHandlerException - If there was an error writing the end of the header.

startQueryResult

public void startQueryResult(List<String> columnHeaders)
                      throws TupleQueryResultHandlerException

Description copied from interface: QueryResultHandler

Indicates the start of a sequence of Solutions. The supplied bindingNames are an indication of the values that are in the Solutions. For example, a SPARQL query like select ?X ?Y where { ?X ?P ?Y } will have binding names X and Y.

Specified by:

startQueryResult in interface QueryResultHandler

Overrides:

startQueryResult in class AbstractQueryResultWriter

Parameters:

columnHeaders - An ordered set of binding names.

Throws:

TupleQueryResultHandlerException - If there was an error during the starting of the query result handler. This exception may be thrown if the QueryResultHandler.handleBoolean(boolean) method was called before this method and the handler cannot process both boolean and tuple results simultaneously.

handleSolutionImpl

protected void handleSolutionImpl(BindingSet bindingSet)
                           throws TupleQueryResultHandlerException

Description copied from class: AbstractQueryResultWriter

Extending classes must implement this method instead of overriding AbstractQueryResultWriter.handleSolution(BindingSet) in order to benefit from automatic handling of RDF-star encoding.

Overrides:

handleSolutionImpl in class AbstractQueryResultWriter

Parameters:

bindingSet - the solution to handle

Throws:

TupleQueryResultHandlerException

endQueryResult

public void endQueryResult()
                    throws TupleQueryResultHandlerException

Description copied from interface: QueryResultHandler

Indicates the end of a sequence of solutions.

Specified by:

endQueryResult in interface QueryResultHandler

Throws:

TupleQueryResultHandlerException - If there was an error during the ending of the query result handler. This exception may be thrown if the QueryResultHandler.handleBoolean(boolean) method was called before this method and the handler cannot process both boolean and tuple results simultaneously.

startDocument

public void startDocument()
                   throws QueryResultHandlerException

Description copied from interface: QueryResultWriter

Indicates the start of the document.

Specified by:

startDocument in interface QueryResultWriter

Throws:

QueryResultHandlerException - If there was an error starting the writing of the results.

handleStylesheet

public void handleStylesheet(String stylesheetUrl)
                      throws QueryResultHandlerException

Description copied from interface: QueryResultWriter

Handles a stylesheet URL. If this is called, it must be called after QueryResultWriter.startDocument() and before QueryResultWriter.startHeader().

NOTE: If the format does not support stylesheets, it must silently ignore calls to this method.

Specified by:

handleStylesheet in interface QueryResultWriter

Parameters:

stylesheetUrl - The URL of the stylesheet to be used to style the results.

Throws:

QueryResultHandlerException - If there was an error handling the stylesheet. This error is not thrown in cases where stylesheets are not supported.

startHeader

public void startHeader()
                 throws QueryResultHandlerException

Description copied from interface: QueryResultWriter

Indicates the start of the header.

Specified by:

startHeader in interface QueryResultWriter

Throws:

QueryResultHandlerException - If there was an error writing the start of the header.

See Also:

• SPARQL Query Results XML Format documentation for head element.

handleLinks

public void handleLinks(List<String> linkUrls)
                 throws QueryResultHandlerException

Description copied from interface: QueryResultHandler

Handles the links elements which are present in SPARQL Results JSON and SPARQL Results XML documents in the header.

NOTE: If the format does not support links, it must silently ignore a call to this method.

An accumulating handler should accumulate these links.

Specified by:

handleLinks in interface QueryResultHandler

Parameters:

linkUrls - The URLs of the links to handle.

Throws:

QueryResultHandlerException - If there was an error handling the set of link URLs. This error is not thrown in cases where links are not supported.

See Also:

• "link"

handleBoolean

public void handleBoolean(boolean value)
                   throws QueryResultHandlerException

Description copied from interface: QueryResultHandler

Handles the specified boolean value.

Specified by:

handleBoolean in interface QueryResultHandler

Parameters:

value - The boolean value to handle.

Throws:

QueryResultHandlerException - If there was an error during the handling of this value. This exception may be thrown if the QueryResultHandler.startQueryResult(List), QueryResultHandler.handleSolution(BindingSet) or QueryResultHandler.endQueryResult() methods were called before this method was called, and the handler cannot process both boolean and tuple results simultaneously.

getSupportedSettings

public final Collection<RioSetting<?>> getSupportedSettings()

Specified by:

getSupportedSettings in interface QueryResultWriter

Overrides:

getSupportedSettings in class AbstractQueryResultWriter

Returns:

A collection of RioSettings that are supported by this QueryResultWriter.

handleNamespace

public void handleNamespace(String prefix,
 String uri)
                     throws QueryResultHandlerException

Description copied from interface: QueryResultWriter

Handles a namespace prefix declaration. If this is called, it should be called before QueryResultWriter.startDocument() to ensure that it has a document wide effect.

NOTE: If the format does not support namespaces, it must silently ignore calls to this method.

Specified by:

handleNamespace in interface QueryResultWriter

Parameters:

prefix - The prefix to use for the namespace

uri - The full URI that is to be represented by the prefix.

Throws:

QueryResultHandlerException

endDocument

protected void endDocument()
                    throws IOException

Throws:

IOException