1 package tim.prune.gui.map;
4 import java.awt.Toolkit;
5 import java.awt.image.ImageObserver;
7 import java.io.FileOutputStream;
8 import java.io.IOException;
9 import java.io.InputStream;
11 import java.net.URLConnection;
12 import java.util.HashSet;
14 import tim.prune.GpsPrune;
17 * Class to control the reading and saving of map tiles
20 public class DiskTileCacher implements Runnable
22 /** URL to get image from */
23 private URL _url = null;
24 /** File to save image to */
25 private File _file = null;
26 /** Observer to be notified */
27 private ImageObserver _observer = null;
28 /** Time limit to cache images for */
29 private static final long CACHE_TIME_LIMIT = 20 * 24 * 60 * 60 * 1000; // 20 days in ms
30 /** Hashset of all blocked / 404 tiles to avoid requesting them again */
31 private static final HashSet<String> BLOCKED_URLS = new HashSet<String>();
35 * @param inUrl URL to get
36 * @param inFile file to save to
38 private DiskTileCacher(URL inUrl, File inFile, ImageObserver inObserver)
42 _observer = inObserver;
46 * Get the specified tile from the disk cache
47 * @param inBasePath base path to whole disk cache
48 * @param inTilePath relative path to requested tile
49 * @return tile image if available, or null if not there
51 public static MapTile getTile(String inBasePath, String inTilePath)
53 if (inBasePath == null) {return null;}
54 File tileFile = new File(inBasePath, inTilePath);
56 if (tileFile.exists() && tileFile.canRead() && tileFile.length() > 0)
58 long fileStamp = tileFile.lastModified();
59 boolean isExpired = ((System.currentTimeMillis()-fileStamp) > CACHE_TIME_LIMIT);
62 image = Toolkit.getDefaultToolkit().createImage(tileFile.getAbsolutePath());
63 return new MapTile(image, isExpired);
66 System.err.println("createImage: " + e.getClass().getName() + " _ " + e.getMessage());
73 * Save the specified image tile to disk
74 * @param inUrl url to get image from
75 * @param inBasePath base path to disk cache
76 * @param inTilePath relative path to this tile
77 * @param inObserver observer to inform when load complete
79 public static void saveTile(URL inUrl, String inBasePath, String inTilePath, ImageObserver inObserver)
81 if (inBasePath == null || inTilePath == null) {return;}
82 // save file if possible
83 File basePath = new File(inBasePath);
84 if (!basePath.exists() || !basePath.isDirectory() || !basePath.canWrite()) {
85 // Can't write to base path
88 File tileFile = new File(basePath, inTilePath);
89 // Check if this file is already being loaded
90 if (isBeingLoaded(tileFile)) {return;}
91 // Check if it has already failed
92 if (BLOCKED_URLS.contains(inUrl.toString())) {return;}
94 File dir = tileFile.getParentFile();
95 // Start a new thread to load the image if necessary
96 if ((dir.exists() || dir.mkdirs()) && dir.canWrite())
98 new Thread(new DiskTileCacher(inUrl, tileFile, inObserver)).start();
103 * Check whether the given tile is already being loaded
104 * @param inFile desired file
105 * @return true if temporary file with this name exists
107 private static boolean isBeingLoaded(File inFile)
109 File tempFile = new File(inFile.getAbsolutePath() + ".temp");
110 if (!tempFile.exists()) {
113 // File exists, so check if it was created recently
114 final long fileAge = System.currentTimeMillis() - tempFile.lastModified();
115 return fileAge < 1000000L; // overwrite if the temp file is still there after 1000s
119 * Run method for loading URL asynchronously and saving to file
123 boolean finished = false;
124 InputStream in = null;
125 FileOutputStream out = null;
126 File tempFile = new File(_file.getAbsolutePath() + ".temp");
127 // Use a synchronized block across all threads to make sure this url is only fetched once
128 synchronized (DiskTileCacher.class)
130 if (tempFile.exists()) {tempFile.delete();}
132 if (!tempFile.createNewFile()) {return;}
134 catch (Exception e) {return;}
138 // Open streams from URL and to file
139 out = new FileOutputStream(tempFile);
140 //System.out.println("Opening URL: " + _url.toString());
141 // Set http user agent on connection
142 URLConnection conn = _url.openConnection();
143 conn.setRequestProperty("User-Agent", "GpsPrune v" + GpsPrune.VERSION_NUMBER);
144 in = conn.getInputStream();
146 // Loop over each byte in the stream (maybe buffering is more efficient?)
147 while ((d = in.read()) >= 0) {
151 } catch (IOException e) {
152 System.err.println("ioe: " + e.getClass().getName() + " - " + e.getMessage());
153 BLOCKED_URLS.add(_url.toString());
158 try {in.close();} catch (Exception e) {} // ignore
159 try {out.close();} catch (Exception e) {} // ignore
164 // Move temp file to desired file location
165 if (tempFile.exists() && !tempFile.renameTo(_file))
167 // File couldn't be moved - delete both to be sure
171 // Tell parent that load is finished (parameters ignored)
172 _observer.imageUpdate(null, ImageObserver.ALLBITS, 0, 0, 0, 0);