src/tim/prune/function/srtm/Srtm3Source.java

   1 package tim.prune.function.srtm;
   2
   3 import java.io.File;
   4 import java.io.FileOutputStream;
   5 import java.io.IOException;
   6 import java.io.InputStream;
   7 import java.net.MalformedURLException;
   8 import java.net.URL;
   9 import java.net.HttpURLConnection;
  10
  11 import tim.prune.GpsPrune;
  12 import tim.prune.I18nManager;
  13
  14 public class Srtm3Source extends SrtmSource {
  15         /** URL prefix for all tiles */
  16         private static final String URL_PREFIX = "https://dds.cr.usgs.gov/srtm/version2_1/SRTM3/";
  17         /** Directory names for each continent */
  18         private static final String[] CONTINENTS = {"", "Eurasia", "North_America", "Australia",
  19                                                     "Islands", "South_America", "Africa"};
  20         private byte[] _continents_lookup;
  21
  22
  23         public Srtm3Source()
  24         {
  25                 _continents_lookup = populateContinents();
  26         }
  27
  28         public String getNameKey()
  29         {
  30                 return "function.downloadsrtm." + getName();
  31         }
  32
  33         public String getName()
  34         {
  35                 return "SRTM3_v21";
  36         }
  37
  38         protected String getSourceExtension()
  39         {
  40                 return ".hgt.zip";
  41         }
  42
  43         /**
  44          * Read the dat file and get the contents
  45          * @return byte array containing file contents
  46          */
  47         private static byte[] populateContinents()
  48         {
  49                 InputStream in = null;
  50                 try
  51                 {
  52                         // Need absolute path to dat file
  53                         in = Srtm3Source.class.getResourceAsStream("/tim/prune/function/srtm/srtmtiles.dat");
  54                         if (in != null)
  55                         {
  56                                 byte[] buffer = new byte[in.available()];
  57                                 in.read(buffer);
  58                                 in.close();
  59                                 return buffer;
  60                         }
  61                 }
  62                 catch (java.io.IOException e) {
  63                         System.err.println("Exception trying to read srtmtiles.dat : " + e.getMessage());
  64                 }
  65                 finally
  66                 {
  67                         try {
  68                                 in.close();
  69                         }
  70                         catch (Exception e) {} // ignore
  71                 }
  72                 return null;
  73         }
  74
  75         /**
  76          * Get the Url for the given tile
  77          * @param inTile Tile to get
  78          * @return URL
  79          */
  80         private URL buildUrl(SrtmTile inTile)
  81                 throws SrtmSourceException
  82         {
  83
  84                 // Get byte from lookup array
  85                 int idx = (inTile.getLatitude() + 59)*360 + (inTile.getLongitude() + 180);
  86                 int dir;
  87                 try
  88                 {
  89                         dir = _continents_lookup[idx];
  90                 }
  91                 catch (ArrayIndexOutOfBoundsException e)
  92                 {
  93                         throw new SrtmSourceException("Could not find continent for tile "+inTile.getTileName());
  94                 }
  95                 try
  96                 {
  97                         return new URL(URL_PREFIX + CONTINENTS[dir] + "/" + inTile.getTileName() + getSourceExtension());
  98                 }
  99                 catch (MalformedURLException e)
 100                 {
 101                         throw new SrtmSourceException("Could not build URL for tile "+inTile.getTileName());
 102                 }
 103         }
 104
 105         public boolean isReadyToUse()
 106         {
 107                 return true;
 108         }
 109
 110         public boolean downloadTile(SrtmTile inTile)
 111                 throws SrtmSourceException
 112         {
 113                 URL tileUrl = buildUrl(inTile);
 114                 File outputFile = getCacheFileName(inTile);
 115                 System.out.println("Download: Need to download: " + tileUrl);
 116
 117                 try
 118                 {
 119                         HttpURLConnection conn = (HttpURLConnection) tileUrl.openConnection();
 120
 121                         // Define streams
 122                         InputStream inStream = null;
 123
 124                         conn.setRequestProperty("User-Agent", "GpsPrune v" + GpsPrune.VERSION_NUMBER);
 125
 126                         int status = conn.getResponseCode();
 127                         if (status == 200)
 128                         {
 129                                 inStream = conn.getInputStream();
 130                         }
 131                         else if (status == 404)
 132                         {
 133                                 throw new SrtmSourceException("Tile not found: "+conn.getURL());
 134                         }
 135                         else
 136                         {
 137                                 throw new SrtmSourceException("Invalid response from server: " +status+conn.getContent());
 138                         }
 139                         return downloadToFile(inStream, outputFile);
 140                 }
 141                 catch (IOException e)
 142                 {
 143                         throw new SrtmSourceException("Error while downloading tile "+inTile.getTileName()+": "+e.getMessage());
 144                 }
 145         }
 146
 147         public int getRowSize(SrtmTile inTile)
 148         {
 149                 return 1201;
 150         }
 151 }