tim/prune/save/GpxCacher.java

   1 package tim.prune.save;
   2
   3 import java.io.File;
   4 import java.io.FileInputStream;
   5 import java.io.InputStream;
   6 import java.util.zip.GZIPInputStream;
   7 import java.util.zip.ZipEntry;
   8 import java.util.zip.ZipInputStream;
   9
  10 import javax.xml.parsers.SAXParser;
  11 import javax.xml.parsers.SAXParserFactory;
  12
  13 import org.xml.sax.Attributes;
  14 import org.xml.sax.SAXException;
  15 import org.xml.sax.helpers.DefaultHandler;
  16
  17 import tim.prune.data.DataPoint;
  18 import tim.prune.data.SourceInfo;
  19
  20 /**
  21  * Class to read in a GPX file and cache all the point strings
  22  */
  23 public class GpxCacher extends DefaultHandler
  24 {
  25         private SourceInfo _sourceInfo = null;
  26         private String _headerString = null;
  27         private String[] _strings = null;
  28         private int _pointNum = 0;
  29         private boolean _insidePoint = false;
  30         private StringBuilder _builder = null;
  31
  32
  33         /**
  34          * Constructor
  35          * @param inSourceInfo source information
  36          */
  37         public GpxCacher(SourceInfo inInfo)
  38         {
  39                 _sourceInfo = inInfo;
  40                 _strings = new String[inInfo.getNumPoints()];
  41                 _pointNum = 0;
  42                 // Should be a gpx file, but might be raw, zipped or gzipped
  43                 File gpxFile = inInfo.getFile();
  44                 String fileName = gpxFile.getName().toLowerCase();
  45                 if (gpxFile.exists() && gpxFile.canRead())
  46                 {
  47                         try {
  48                                 SAXParser saxParser = SAXParserFactory.newInstance().newSAXParser();
  49                                 if (fileName.endsWith(".gpx") || fileName.endsWith(".xml")) {
  50                                         saxParser.parse(inInfo.getFile(), this);
  51                                 }
  52                                 else if (fileName.endsWith(".zip")) {
  53                                         saxParser.parse(getZipInputStream(inInfo.getFile()), this);
  54                                 }
  55                                 else if (fileName.endsWith(".gz")) {
  56                                         saxParser.parse(new GZIPInputStream(new FileInputStream(inInfo.getFile())), this);
  57                                 }
  58                                 else {
  59                                         System.out.println("GpxCacher unrecognised file type: " + inInfo.getFile().getName());
  60                                 }
  61                         } catch (Exception e) {
  62                                 // TODO: Handle errors here with a list of warnings?
  63                                 e.printStackTrace();
  64                         }
  65                 }
  66                 _builder = null;
  67         }
  68
  69
  70         /**
  71          * Receive the start of a tag
  72          */
  73         public void startElement(String inUri, String inLocalName, String inTagName,
  74                 Attributes inAttributes) throws SAXException
  75         {
  76                 if (inTagName.equalsIgnoreCase("gpx"))
  77                 {
  78                         // store initial gpx tag
  79                         _builder = new StringBuilder(60);
  80                         appendTag(_builder, inTagName, inAttributes);
  81                         _headerString = _builder.toString();
  82                 }
  83                 else
  84                 {
  85                         if (inTagName.equalsIgnoreCase("wpt") || inTagName.equalsIgnoreCase("trkpt")
  86                                 || inTagName.equalsIgnoreCase("rtept"))
  87                         {
  88                                 _insidePoint = true;
  89                                 _builder = new StringBuilder(60);
  90                         }
  91                         if (_insidePoint) {
  92                                 appendTag(_builder, inTagName, inAttributes);
  93                         }
  94                 }
  95                 super.startElement(inUri, inLocalName, inTagName, inAttributes);
  96         }
  97
  98         /**
  99          * Receive characters between tags (inside or outside)
 100          */
 101         public void characters(char[] inChars, int inStart, int inLength)
 102                 throws SAXException
 103         {
 104                 if (_insidePoint) {
 105                         _builder.append(new String(inChars, inStart, inLength));
 106                 }
 107                 super.characters(inChars, inStart, inLength);
 108         }
 109
 110         /**
 111          * Receive end of xml tag
 112          */
 113         public void endElement(String inUri, String inLocalName, String inTagName)
 114                 throws SAXException
 115         {
 116                 if (_insidePoint) {
 117                         _builder.append("</").append(inTagName).append('>');
 118                 }
 119                 if (inTagName.equalsIgnoreCase("wpt") || inTagName.equalsIgnoreCase("trkpt")
 120                         || inTagName.equalsIgnoreCase("rtept"))
 121                 {
 122                         _strings[_pointNum] = _builder.toString();
 123                         _pointNum++;
 124                         _insidePoint = false;
 125                 }
 126                 super.endElement(inUri, inLocalName, inTagName);
 127         }
 128
 129
 130         /**
 131          * Append the current tag to the supplied StringBuilder
 132          * @param inBuilder Stringbuilder object to append tag to
 133          * @param inTagName name of tag
 134          * @param inAttributes attributes of tag
 135          */
 136         private static void appendTag(StringBuilder inBuilder, String inTagName, Attributes inAttributes)
 137         {
 138                 inBuilder.append('<').append(inTagName);
 139                 int numAtts = inAttributes.getLength();
 140                 for (int i=0; i<numAtts; i++) {
 141                         inBuilder.append(' ').append(inAttributes.getQName(i)).append("=\"")
 142                                 .append(inAttributes.getValue(i)).append('"');
 143                 }
 144                 inBuilder.append('>');
 145         }
 146
 147
 148         /**
 149          * @return the header string from the GPX tag
 150          */
 151         public String getHeaderString()
 152         {
 153                 return _headerString;
 154         }
 155
 156         /**
 157          * Get the source string for the given point
 158          * @param inPoint point to retrieve
 159          * @return string if found, otherwise null
 160          */
 161         public String getSourceString(DataPoint inPoint)
 162         {
 163                 int index = _sourceInfo.getIndex(inPoint);
 164                 if (index >= 0) {
 165                         return _strings[index];
 166                 }
 167                 return null;
 168         }
 169
 170         /**
 171          * Get an inputstream of a GPX file inside a zip
 172          * @param inFile File object describing zip file
 173          * @return input stream for Xml parser
 174          */
 175         private static InputStream getZipInputStream(File inFile)
 176         {
 177                 try
 178                 {
 179                         ZipInputStream zis = new ZipInputStream(new FileInputStream(inFile));
 180                         while (zis.available() > 0)
 181                         {
 182                                 ZipEntry entry = zis.getNextEntry();
 183                                 String entryName = entry.toString();
 184                                 if (entryName != null && entryName.length() > 4)
 185                                 {
 186                                         String suffix = entryName.substring(entryName.length()-4).toLowerCase();
 187                                         if (suffix.equals(".gpx") || suffix.equals(".xml")) {
 188                                                 // First matching file so must be gpx
 189                                                 return zis;
 190                                         }
 191                                 }
 192                         }
 193                 }
 194                 catch (Exception e) {} // ignore errors
 195                 // not found - error!
 196                 return null;
 197         }
 198 }