src/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
  25         /** Hashset of all blocked / 404 tiles to avoid requesting them again */
  26         private static final HashSet<String> BLOCKED_URLS = new HashSet<String>();
  27         /** Hashset of all currently loading tiles to avoid requesting them again */
  28         private static final HashSet<String> LOADING_URLS = new HashSet<String>();
  29         /** Flag to maintain whether connection is active or not */
  30         private static boolean CONNECTION_ACTIVE = true;
  31
  32
  33         /**
  34          * Constructor (private)
  35          * @param inManager parent manager for callback
  36          * @param inUrl URL to load
  37          * @param inLayer layer index from 0
  38          * @param inX x coordinate of tile
  39          * @param inY y coordinate of tile
  40          * @param inZoom zoom level
  41          */
  42         private TileDownloader(MapTileManager inManager, URL inUrl, int inLayer, int inX, int inY, int inZoom)
  43         {
  44                 _manager = inManager;
  45                 _url = inUrl;
  46                 _layer = inLayer;
  47                 _x = inX; _y = inY;
  48                 _zoom = inZoom;
  49         }
  50
  51         /**
  52          * Trigger a download in a new thread
  53          * @param inManager manager to callback when image is loaded
  54          * @param inUrl URL to load
  55          * @param inLayer layer index from 0
  56          * @param inX x coordinate of tile
  57          * @param inY y coordinate of tile
  58          * @param inZoom current zoom level
  59          */
  60         public static synchronized void triggerLoad(MapTileManager inManager, URL inUrl, int inLayer,
  61                 int inX, int inY, int inZoom)
  62         {
  63                 if (inManager != null && inUrl != null)
  64                 {
  65                         String url = inUrl.toString();
  66                         // System.out.println("Trigger load: " + url);
  67                         if (!BLOCKED_URLS.contains(url) && !LOADING_URLS.contains(url))
  68                         {
  69                                 // System.out.println("Not blocked: " + url);
  70                                 LOADING_URLS.add(url);
  71                                 new Thread(new TileDownloader(inManager, inUrl, inLayer, inX, inY, inZoom)).start();
  72                         }
  73                         else {
  74                                 System.out.println("Already blocked: " + url);
  75                         }
  76                 }
  77         }
  78
  79         /**
  80          * Run method, called in separate thread
  81          */
  82         public void run()
  83         {
  84                 InputStream in = null;
  85                 try
  86                 {
  87                         // System.out.println("TD Running thread to get: " + _url.toString());
  88                         // Set http user agent on connection
  89                         URLConnection conn = _url.openConnection();
  90                         conn.setRequestProperty("User-Agent", "GpsPrune v" + GpsPrune.VERSION_NUMBER);
  91                         in = conn.getInputStream();
  92                         int len = conn.getContentLength();
  93                         if (len > 0)
  94                         {
  95                                 byte[] data = new byte[len];
  96                                 int totalRead = 0;
  97                                 while (totalRead < len)
  98                                 {
  99                                         int numRead = in.read(data, totalRead, len-totalRead);
 100                                         totalRead += numRead;
 101                                 }
 102                                 Image tile = Toolkit.getDefaultToolkit().createImage(data);
 103                                 in.close();
 104
 105                                 // Pass back to manager so it can be stored in its memory cache
 106                                 _manager.notifyImageLoaded(tile, _layer, _x, _y, _zoom);
 107
 108                                 if (!CONNECTION_ACTIVE)
 109                                 {
 110                                         // We've just come back online, so forget which tiles gave 404 before
 111                                         System.out.println("Deleting blocked urls, currently holds " + BLOCKED_URLS.size());
 112                                         synchronized(this.getClass())
 113                                         {
 114                                                 BLOCKED_URLS.clear();
 115                                         }
 116                                         CONNECTION_ACTIVE = true;
 117                                 }
 118                         }
 119                 }
 120                 catch (IOException e)
 121                 {
 122                         System.err.println("IOE: " + e.getClass().getName() + " - " + e.getMessage());
 123                         synchronized(this.getClass())
 124                         {
 125                                 BLOCKED_URLS.add(_url.toString());
 126                         }
 127                         try {in.close();} catch (Exception e2) {}
 128                         CONNECTION_ACTIVE = false;      // lost connection?
 129                 }
 130                 LOADING_URLS.remove(_url.toString());
 131         }
 132 }