src/tim/prune/function/srtm/SrtmGl1Source.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.CookieHandler;
   8 import java.net.CookieManager;
   9 import java.net.CookiePolicy;
  10 import java.net.MalformedURLException;
  11 import java.net.URL;
  12 import java.net.HttpURLConnection;
  13
  14 import tim.prune.App;
  15 import tim.prune.GpsPrune;
  16 import tim.prune.config.Config;
  17
  18 /**
  19  * Create an account at: https://urs.earthdata.nasa.gov/users/new
  20  * Data policy: https://lpdaac.usgs.gov/data/data-citation-and-policies/
  21  *
  22  */
  23
  24 public class SrtmGl1Source extends SrtmSource {
  25         /** URL prefix for all tiles */
  26         private static final String URL_PREFIX = "https://e4ftl01.cr.usgs.gov/MEASURES/SRTMGL1.003/2000.02.11/";
  27         /** Auth URL */
  28         private static final String AUTH_URL = "urs.earthdata.nasa.gov";
  29
  30
  31         public SrtmGl1Source()
  32         {
  33                 CookieHandler.setDefault(new CookieManager(null, CookiePolicy.ACCEPT_ALL));
  34         }
  35
  36         public String getName()
  37         {
  38                 return "SRTMGL1_v003";
  39         }
  40
  41         protected String getSourceExtension()
  42         {
  43                 return ".SRTMGL1.hgt.zip";
  44         }
  45
  46         private URL buildUrl(SrtmTile inTile)
  47                 throws SrtmSourceException
  48         {
  49                 try {
  50                         return new URL(URL_PREFIX + inTile.getTileName() + getSourceExtension());
  51                 }
  52                 catch (MalformedURLException e)
  53                 {
  54                         throw new SrtmSourceException(e.getMessage());
  55                 }
  56         }
  57
  58         public boolean isReadyToUse()
  59         {
  60                 return getAuth() != null;
  61         }
  62
  63         private String getAuth()
  64         {
  65                 String authString = Config.getConfigString(Config.KEY_EARTHDATA_AUTH);
  66                 if (authString != null)
  67                 {
  68                         return "Basic " + authString;
  69                 }
  70                 else
  71                 {
  72                         return null;
  73                 }
  74         }
  75
  76         public boolean downloadTile(SrtmTile inTile)
  77                 throws SrtmSourceException
  78         {
  79                 return downloadTile(inTile, getAuth());
  80         }
  81
  82         private boolean downloadTile(SrtmTile inTile, String auth)
  83                 throws SrtmSourceException
  84         {
  85                 URL tileUrl = buildUrl(inTile);
  86                 File outputFile = getCacheFileName(inTile);
  87                 try
  88                 {
  89                         HttpURLConnection conn = (HttpURLConnection) tileUrl.openConnection();
  90                         // Define streams
  91                         InputStream inStream = null;
  92
  93                         // Documentation about HTTP interface at:
  94                         // https://wiki.earthdata.nasa.gov/display/EL/How+To+Access+Data+With+Java
  95                         int redirects = 0;
  96
  97                         while (redirects < 10) {
  98                                 redirects++;
  99
 100                                 conn.setRequestProperty("User-Agent", "GpsPrune v" + GpsPrune.VERSION_NUMBER);
 101                                 conn.setInstanceFollowRedirects(false);
 102                                 conn.setUseCaches(false);
 103                                 if (conn.getURL().getHost().equals(AUTH_URL))
 104                                 {
 105                                         conn.setRequestProperty("Authorization", auth);
 106                                 }
 107
 108                                 int status = conn.getResponseCode();
 109                                 if (status == 200)
 110                                 {
 111                                         // Found the tile, we're good
 112                                         inStream = conn.getInputStream();
 113                                         break;
 114                                 }
 115                                 else if (status == 302)
 116                                 {
 117                                         // redirected to SSO server then back to original resource
 118                                         String newUrl = conn.getHeaderField("Location");
 119                                         conn = (HttpURLConnection) (new URL(newUrl)).openConnection();
 120                                 }
 121                                 else if (status == 404)
 122                                 {
 123                                         throw new SrtmSourceException("Tile " + inTile.getTileName() + " not found at " + conn.getURL());
 124                                 }
 125                                 else
 126                                 {
 127                                         throw new SrtmSourceException("Invalid response from server: " + status + conn.getResponseMessage());
 128                                 }
 129                         }
 130
 131                         return readToFile(inStream, outputFile);
 132                 }
 133                 catch (IOException e)
 134                 {
 135                         throw new SrtmSourceException("Error while downloading tile " + inTile.getTileName() + ": "+e.getMessage());
 136                 }
 137         }
 138
 139         public boolean testAuth(String auth)
 140                 throws SrtmSourceException
 141         {
 142                 // The only thing special about this tile is that it's the smallest tile
 143                 // It covers small islands in Malaysia
 144                 SrtmTile testTile = new SrtmTile(7, 117);
 145                 if (isCached(testTile))
 146                 {
 147                         getCacheFileName(testTile).delete();
 148                 }
 149                 return downloadTile(testTile, auth);
 150         }
 151
 152         public int getRowSize(SrtmTile inTile)
 153         {
 154                 return 3601;
 155         }
 156 }