Android Open Source - mapped Parser

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License

The source code is released under:

Apache License

Java Source Code

package com.chalmers.frapp.database;
/*from w  w w .j a va  2  s. c  o m*/
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.LinkedList;
import android.util.Pair;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
import com.google.android.maps.GeoPoint;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

/**
 * A parser class to create a new LocationDatabse from a
 * given XML file.
 * 
 * The general design is to use a stack representing the
 * currently open XML tags or XML path. Each tag includes
 * a parser state containing various data to be processed
 * by this parser class.
 */
public class Parser extends DefaultHandler {

  /**
   * Enumeration of parsed tags.
   */
  private enum XMLTags {
    BUILDINGS,
    BUILDING,
    ENTRANCES,
    ENTRANCE,
    ADDRESS,
    GEOPOINT,
    LOCATIONS,
    LOCATION,
    ENTRANCEID,
    CATEGORY,
    DESCRIPTION
  };

  /**
   * The database which holds the parsed data.
   */
  private LocationDatabase database;
  /**
   * A stack to hold the current XML path and additional
   * parser states.
   */
  private LinkedList<Pair<XMLTags, Object>> parseStack;

  /**
   * Parse an InputStream to a LocationDatabase.
   * 
   * @param inputStream An InputStream to parse.
   * @throws ParserConfigurationException
   * @throws SAXException
   * @throws IOException
   */
  public Parser(InputStream inputStream) throws ParserConfigurationException, SAXException, IOException {
    database = new LocationDatabase();
    parseStack = new LinkedList<Pair<XMLTags, Object>>();
    
    // getting SAXParserFactory instance
    SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
  
    // Getting SAXParser object from AXParserFactory instance
    SAXParser saxParser = saxParserFactory.newSAXParser();
  
    // Parsing XML Document by calling parse method of SAXParser class
    saxParser.parse(inputStream, this);
  }

  /**
   * Get the parsed database.
   * 
   * @return A LocationDatabase filled with parsed information.
   */
  public LocationDatabase getDatabase() {
    return database;
  }

  /**
   * Parse a geopoint tag.
   * 
   * @param atts Attributes from the SAX parser. 
   * @return A parsed GeoPoint
   * @throws SAXException
   */
  private GeoPoint parseGeopoint(Attributes atts) throws SAXException {
    Integer latitude = null;
    Integer longitude = null;
    int attributeCount = 0;
    for(int i = 0; i < atts.getLength(); i++) {
      // Accept attribute "lat".
      if(latitude == null && atts.getLocalName(i).toLowerCase().equals("lat")) {
        latitude = (int) (Double.parseDouble(atts.getValue(i)) * 1E6);
      
      // Accept attribute "long".
      } else if(longitude == null && atts.getLocalName(i).toLowerCase().equals("long")) {
        longitude = (int) (Double.parseDouble(atts.getValue(i)) * 1E6);

      // Any other attributes is an error.
      } else {
        throw new SAXException("Unexpected attribute: " + atts.getLocalName(i) + ", expected lat and long.");
      }
      attributeCount++;
    }

    // There must be exactly two attributes ("lat" and "long").
    if(attributeCount != 2) {
      throw new SAXException("Unexpected attribute count: " + attributeCount + ", expected two.");
    }

    return new GeoPoint(latitude, longitude);
  }

    public void startElement(String uri, String localName, String qName,
            Attributes atts) throws SAXException {
      // If the current XML path is empty.
      if(parseStack.isEmpty()) {
        // Accept tag "buildings".
        if(localName.toLowerCase().equals("buildings")) {
          // Update the XML path
            parseStack.add(new Pair<XMLTags, Object>(XMLTags.BUILDINGS, null));

          // Any other tag is an error.
        } else {
          throw new SAXException("Unexpected tag: " + localName + ", expected buildings.");
        }

      // Currently processing a "buildings" tag.
      } else if(parseStack.peekLast().first.equals(XMLTags.BUILDINGS)) {
        // Accept any number of "building" tags.
        if(localName.toLowerCase().equals("building")) {
            int attributeCount = 0;
            for(int i = 0; i < atts.getLength(); i++) {
              // Accept the "name" XML attribute. 
              if(atts.getLocalName(i).toLowerCase().equals("name")) {
                // Update the XML path and include a building state connected to the database.
                parseStack.add(new Pair<XMLTags, Object>(XMLTags.BUILDING, database.addBuilding(atts.getValue(i))));

              // Any incorrect attribute is an error.
              } else {
                throw new SAXException("Unexpected attribute: " + atts.getLocalName(i) + ", expected name.");
              }
              attributeCount++;
            }
     
            // There must be exactly one attribute (and that is "name").
            if(attributeCount != 1) {
              throw new SAXException("Unexpected attribute count: " + attributeCount + ", expected one.");
            }

          // Any other tag is an error.
        } else {
          throw new SAXException("Unexpected tag: " + localName + ", expected building.");
        }

      // Currently processing a "building" tag.
      } else if(parseStack.peekLast().first.equals(XMLTags.BUILDING)) {
        // Accept "entrance" tag.
        if(localName.toLowerCase().equals("entrances")) {
          // Update the XML path and include the current building state.
          parseStack.add(new Pair<XMLTags, Object>(XMLTags.ENTRANCES, parseStack.peekLast().second));

        // Accept "location" tag.
        } else if(localName.toLowerCase().equals("locations")) {
          // Update the XML path and include the current building state.
          parseStack.add(new Pair<XMLTags, Object>(XMLTags.LOCATIONS, parseStack.peekLast().second));

        // Any other tag is an error.
        } else {
          throw new SAXException("Unexpected tag: " + localName + ", expected entrances or locations.");
        }
      
      // Currently processing a "entrances"  tag.
      } else if(parseStack.peekLast().first.equals(XMLTags.ENTRANCES)) {
        // Accept "entrance" tag.
        if(localName.toLowerCase().equals("entrance")) {
            int attributeCount = 0;
            for(int i = 0; i < atts.getLength(); i++) {
              if(atts.getLocalName(i).toLowerCase().equals("id")) {
                // Create a new state for this entrance.
                ArrayList<Object> entranceData = new ArrayList<Object>(3);
                entranceData.add(atts.getValue(i)); // The entrance ID (String)
                entranceData.add(null);             // Placeholder for address (String)
                entranceData.add(null);             // Placeholder for location (GeoPoint)
                
                // Update the XML path and use the new entrance state.
                // Note: see processing of the "entrance" tag and the
                // method characters for filling all placeholders.
                parseStack.add(new Pair<XMLTags, Object>(XMLTags.ENTRANCE, entranceData));      
              } else {
                throw new SAXException("Unexpected attribute: " + atts.getLocalName(i) + ", expected id.");
              }
              attributeCount++;
            }

            if(attributeCount != 1) {
              throw new SAXException("Unexpected attribute count: " + attributeCount + ", expected one.");
            }
        } else {
          throw new SAXException("Unexpected tag: " + localName + ", expected entrance.");
        }

      // Process "entrance" tag.
      } else if(parseStack.peekLast().first.equals(XMLTags.ENTRANCE)) {
        ArrayList<Object> entranceData = (ArrayList<Object>) parseStack.peekLast().second;
        if(entranceData.get(1) == null && localName.toLowerCase().equals("address")) {
          parseStack.add(new Pair<XMLTags, Object>(XMLTags.ADDRESS, entranceData));
        } else if(entranceData.get(2) == null && localName.toLowerCase().equals("geopoint")) {
            entranceData.set(2, parseGeopoint(atts));
            parseStack.add(new Pair<XMLTags, Object>(XMLTags.GEOPOINT, null));
        } else {
          throw new SAXException("Unexpected tag: " + localName + ", expected address or geopoint.");
        }

      // Process "locations" tag.
      } else if(parseStack.peekLast().first.equals(XMLTags.LOCATIONS)) {
        if(localName.toLowerCase().equals("location")) {
            int attributeCount = 0;
            for(int i = 0; i < atts.getLength(); i++) {
              if(atts.getLocalName(i).toLowerCase().equals("name")) {
                // Create a new state for this location/room.
                ArrayList<Object> locationData = new ArrayList<Object>(5);
                locationData.add(atts.getValue(i));         // Room name.
                locationData.add(new LinkedList<String>()); // List of entranceIDs.
                locationData.add(new LinkedList<String>()); // List of categories.
                locationData.add(null);                     // GeoPoint placeholder.
                locationData.add(null);                     // Description placeholder.
                parseStack.add(new Pair<XMLTags, Object>(XMLTags.LOCATION, locationData));
              } else {
                throw new SAXException("Unexpected attribute: " + atts.getLocalName(i) + ", expected name.");
              }
              attributeCount++;
            }

            if(attributeCount != 1) {
              throw new SAXException("Unexpected attribute count: " + attributeCount + ", expected one.");
            }
        } else {
          throw new SAXException("Unexpected tag: " + localName + ", expected location.");
        }

      // Process "location" tag.
      } else if(parseStack.peekLast().first.equals(XMLTags.LOCATION)) {
        ArrayList<Object> locationData = (ArrayList<Object>) parseStack.peekLast().second;
        if(localName.toLowerCase().equals("entrance")) {
          parseStack.add(new Pair<XMLTags, Object>(XMLTags.ENTRANCEID, locationData.get(1)));
        } else if(localName.toLowerCase().equals("category")) {
          parseStack.add(new Pair<XMLTags, Object>(XMLTags.CATEGORY, locationData.get(2)));
        } else if(localName.toLowerCase().equals("geopoint")) {
          locationData.set(3, parseGeopoint(atts));
            parseStack.add(new Pair<XMLTags, Object>(XMLTags.GEOPOINT, null));
        } else if(localName.toLowerCase().equals("description")) {
          parseStack.add(new Pair<XMLTags, Object>(XMLTags.DESCRIPTION, locationData));
        } else {
          throw new SAXException("Unexpected tag: " + localName + ", expected entrance, category, geopoint or description.");
        }
      }

      // No other interesting start states should be present.
    }

    public void characters(char[] ch, int start, int length)
        throws SAXException {
      // Process "address" tag under "entrance".
      if(parseStack.peekLast().first.equals(XMLTags.ADDRESS)) {
        ArrayList<Object> entranceData = (ArrayList<Object>) parseStack.peekLast().second;
        String address = new String(ch, start, length);
        entranceData.set(1, address);
  
      // Process "entrance" tag under "location" (room).
      } else if(parseStack.peekLast().first.equals(XMLTags.ENTRANCEID)) {
        LinkedList<String> entrances = (LinkedList<String>) parseStack.peekLast().second;
        String entranceID = new String(ch, start, length);
        entrances.add(entranceID);

      // Process "category" tag under "location" (room).
      } else if(parseStack.peekLast().first.equals(XMLTags.CATEGORY)) {
      LinkedList<String> categoryList = (LinkedList<String>) parseStack.peekLast().second;
      String category = new String(ch, start, length);
      categoryList.add(category);

    // Process "description" tag under "location" (room).
      } else if(parseStack.peekLast().first.equals(XMLTags.DESCRIPTION)) {
        ArrayList<Object> locationData = (ArrayList<Object>) parseStack.peekLast().second;
        String description = new String(ch, start, length);
        locationData.set(4, description);
      }
    }
    
    public void endElement(String uri, String localName, String qName) 
            throws SAXException {
      // Pop the current parse state from the parse stack
      Pair<XMLTags, Object> current = parseStack.removeLast();

      // When closing an "entrance" tag, add it to the building.
      if(current.first.equals(XMLTags.ENTRANCE)) {
        ArrayList<Object> entranceData = (ArrayList<Object>) current.second;
        Building b = (Building) parseStack.peekLast().second;
        b.addEntrance((String) entranceData.get(0), (String) entranceData.get(1), (GeoPoint) entranceData.get(2));
 
      // When closing an "location" tag (room), add it to the building.
      } else if(current.first.equals(XMLTags.LOCATION)) {
        ArrayList<Object> locationData = (ArrayList<Object>) current.second;
        Building b = (Building) parseStack.peekLast().second;
        Room newRoom = b.addRoom((String) locationData.get(0), (String) locationData.get(4), (LinkedList<String>) locationData.get(1), (GeoPoint) locationData.get(3));
        newRoom.getCategories().addAll((LinkedList<String>) locationData.get(2));
      }
    }
 
    public void endDocument() throws SAXException {
      // If the parse stack is not empty at the end of the XML document
      // then the XML document is incorrect.
      if(!parseStack.isEmpty()) {
        throw new SAXException("Unexpected end of document.");
      }
    }
}

Java Source Code List

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