package org.autoplot.datasource; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.nio.ByteBuffer; import java.nio.channels.FileChannel; import java.util.logging.Level; import java.util.logging.Logger; import javax.xml.parsers.ParserConfigurationException; import javax.xml.parsers.SAXParser; import javax.xml.parsers.SAXParserFactory; import jdk.nashorn.internal.parser.JSONParser; import org.das2.datum.LoggerManager; import org.das2.util.FileUtil; import org.json.JSONException; import org.json.JSONObject; import org.xml.sax.Attributes; import org.xml.sax.SAXException; import org.xml.sax.XMLReader; import org.xml.sax.helpers.DefaultHandler; /** * One-stop for guessing the data source type based on schemas and tags. Presently * this recognizes just JSON and XML types, but might also be used to identify files * by magic numbers (bytes f3 cd for CDF, ASCII %PDF for PDF). * @author jbf */ public class DataSourceRecognizer { public static String guessDataSourceType( File f ) throws IOException { FileChannel channel= new FileInputStream(f).getChannel(); ByteBuffer buf= channel.map( FileChannel.MapMode.READ_ONLY, 0, 1024 ); ByteBuffer fer= channel.map( FileChannel.MapMode.READ_ONLY, channel.size()-1024, 1024 ); if ( buf.limit()>5 && buf.get(0)=='<' && buf.get(1)=='?' && buf.get(2)=='x' && buf.get(3)=='m' && buf.get(4)=='l' ) { return guessDataSourceTypeXML(f); } else if ( buf.limit()>1 && buf.get(0)=='{' ) { for ( int i=1023; i>1000; i-- ) { byte c= fer.get(i); if ( !Character.isWhitespace(c) ) { if ( c=='}' ) { return guessDataSourceTypeJSON(f); } else { break; } } } return null; } else { return null; } } private static final Logger logger= LoggerManager.getLogger("apdss.xml"); public static final String TYPE_HELM = "HELM"; public static final String TYPE_SPASE = "SPASE"; public static final String TYPE_VOTABLE = "VOTABLE"; public static final String TYPE_MISC = "MISC"; private Object type; private static final String ID_XML_TYPE = "got the type"; private static class MyDefaultHandler extends DefaultHandler { private String type; /** * initialize the state to STATE_OPEN. */ @Override public void startDocument() throws SAXException { } /** * As elements come in, we go through the state transitions to keep track of * whether we are reading FIELDS, Rows of the dataset, Individual columns, etc. */ @Override public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { switch (localName) { case "VOTABLE": type= "vap+xml"; throw new RuntimeException(ID_XML_TYPE); // abort from parsing case "Spase": type= "vap+xml"; throw new RuntimeException(ID_XML_TYPE); // abort from parsing case "Eventlist": type= "vap+xml"; throw new RuntimeException(ID_XML_TYPE); // abort from parsing case "Product_Observational": type= "vap+pds4"; throw new RuntimeException(ID_XML_TYPE); // abort from parsing default: throw new IllegalArgumentException("Unrecognized XML type: "+uri); } } }; /** * return the type for the XML file. Three types, SPASE, EventList, and VOTABLE * are all handled by the vap+xmln, and the fourth is vap+pds4. * @param f * @return * @throws IOException */ public static String guessDataSourceTypeXML( File f ) throws IOException { XMLReader xmlReader=null; MyDefaultHandler handler= new MyDefaultHandler(); try { SAXParserFactory spf = SAXParserFactory.newInstance(); spf.setNamespaceAware(true); SAXParser saxParser = spf.newSAXParser(); xmlReader = saxParser.getXMLReader(); xmlReader.setContentHandler( handler ); } catch (SAXException | ParserConfigurationException ex) { logger.log(Level.SEVERE, null, ex); throw new RuntimeException(ex); } try { xmlReader.parse( f.toURI().toString() ); } catch ( RuntimeException ex ) { // should happen because we threw ID_XML_TYPE } catch (SAXException ex) { logger.log(Level.SEVERE, null, ex); } return handler.type; } /** * return the type, if recognized, of the JSON file. * @param f * @return * @throws IOException */ public static String guessDataSourceTypeJSON( File f ) throws IOException { try { long t0= System.currentTimeMillis(); String json= FileUtil.readFileToString(f); System.err.println("read to string: "+(System.currentTimeMillis()-t0)); JSONObject obj= new JSONObject(json); System.err.println("read to JSONObject: "+(System.currentTimeMillis()-t0)); if ( obj.has("crs") && obj.has("fields") ) { return "vap+tfcat"; } else { return null; } } catch (JSONException ex) { return null; } } }