tim/prune/gui/map/TileDownloader.java

   1 package tim.prune.gui.map;
   2
   3 import java.awt.Image;
   4 import java.awt.Toolkit;
   5 import java.io.IOException;
   6 import java.io.InputStream;
   7 import java.net.URL;
   8 import java.net.URLConnection;
   9 import java.util.HashSet;
  10
  11 import tim.prune.GpsPrune;
  12
  13 /**
  14  * Class to asynchronously download a tile from a url
  15  * and populate an Image object with the contents
  16  */
  17 public class TileDownloader implements Runnable
  18 {
  19         private MapTileManager _manager = null;
  20         private URL _url = null;
  21         private int _layer = 0;
  22         private int _x = 0, _y = 0;
  23         private int _zoom = 0;
  24         /** Hashset of all blocked / 404 tiles to avoid requesting them again */
  25         private static final HashSet<String> BLOCKED_URLS = new HashSet<String>();
  26         /** Hashset of all currently loading tiles to avoid requesting them again */
  27         private static final HashSet<String> LOADING_URLS = new HashSet<String>();
  28
  29
  30         /**
  31          * Constructor (private)
  32          * @param inManager parent manager for callback
  33          * @param inUrl URL to load
  34          * @param inLayer layer index from 0
  35          * @param inX x coordinate of tile
  36          * @param inY y coordinate of tile
  37          * @param inZoom zoom level
  38          */
  39         private TileDownloader(MapTileManager inManager, URL inUrl, int inLayer, int inX, int inY, int inZoom)
  40         {
  41                 _manager = inManager;
  42                 _url = inUrl;
  43                 _layer = inLayer;
  44                 _x = inX; _y = inY;
  45                 _zoom = inZoom;
  46         }
  47
  48         /**
  49          * Trigger a download in a new thread
  50          * @param inManager manager to callback when image is loaded
  51          * @param inUrl URL to load
  52          * @param inLayer layer index from 0
  53          * @param inX x coordinate of tile
  54          * @param inY y coordinate of tile
  55          * @param inZoom current zoom level
  56          */
  57         public static synchronized void triggerLoad(MapTileManager inManager, URL inUrl, int inLayer,
  58                 int inX, int inY, int inZoom)
  59         {
  60                 if (inManager != null && inUrl != null)
  61                 {
  62                         String url = inUrl.toString();
  63                         if (!BLOCKED_URLS.contains(url) && !LOADING_URLS.contains(url))
  64                         {
  65                                 LOADING_URLS.add(url);
  66                                 new Thread(new TileDownloader(inManager, inUrl, inLayer, inX, inY, inZoom)).start();
  67                         }
  68                 }
  69         }
  70
  71         /**
  72          * Run method, called in separate thread
  73          */
  74         public void run()
  75         {
  76                 InputStream in = null;
  77                 try
  78                 {
  79                         // Set http user agent on connection
  80                         URLConnection conn = _url.openConnection();
  81                         conn.setRequestProperty("User-Agent", "GpsPrune v" + GpsPrune.VERSION_NUMBER);
  82                         in = conn.getInputStream();
  83                         int len = conn.getContentLength();
  84                         if (len > 0)
  85                         {
  86                                 byte[] data = new byte[len];
  87                                 int totalRead = 0;
  88                                 while (totalRead < len)
  89                                 {
  90                                         int numRead = in.read(data, totalRead, len-totalRead);
  91                                         totalRead += numRead;
  92                                 }
  93                                 Image tile = Toolkit.getDefaultToolkit().createImage(data);
  94                                 in.close();
  95
  96                                 // Pass back to manager so it can be stored in its memory cache
  97                                 _manager.notifyImageLoaded(tile, _layer, _x, _y, _zoom);
  98                         }
  99                 }
 100                 catch (IOException e)
 101                 {
 102                         System.err.println("IOE: " + e.getClass().getName() + " - " + e.getMessage());
 103                         synchronized(this.getClass())
 104                         {
 105                                 BLOCKED_URLS.add(_url.toString());
 106                         }
 107                         try {in.close();} catch (Exception e2) {}
 108                 }
 109                 LOADING_URLS.remove(_url.toString());
 110         }
 111 }