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;
43 new Thread(this).start();
47 * Get the specified tile from the disk cache
48 * @param inBasePath base path to whole disk cache
49 * @param inTilePath relative path to requested tile
50 * @param inCheckAge true to check age of file, false to ignore
51 * @return tile image if available, or null if not there
53 public static Image getTile(String inBasePath, String inTilePath, boolean inCheckAge)
55 if (inBasePath == null) {return null;}
56 File tileFile = new File(inBasePath, inTilePath);
58 if (tileFile.exists() && tileFile.canRead() && tileFile.length() > 0)
60 long fileStamp = tileFile.lastModified();
61 if (!inCheckAge || ((System.currentTimeMillis()-fileStamp) < CACHE_TIME_LIMIT))
64 image = Toolkit.getDefaultToolkit().createImage(tileFile.getAbsolutePath());
66 catch (Exception e) {}
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
78 * @return true if successful, false for failure
80 public static boolean saveTile(URL inUrl, String inBasePath, String inTilePath, ImageObserver inObserver)
82 if (inBasePath == null || inTilePath == null) {return false;}
83 // save file if possible
84 File basePath = new File(inBasePath);
85 if (!basePath.exists() || !basePath.isDirectory() || !basePath.canWrite()) {
86 // Can't write to base path
89 File tileFile = new File(basePath, inTilePath);
90 // Check if this file is already being loaded
91 if (isBeingLoaded(tileFile)) {return true;}
92 // Check if it has already failed
93 if (BLOCKED_URLS.contains(inUrl.toString())) {return true;}
95 File dir = tileFile.getParentFile();
96 // Start a new thread to load the image if necessary
97 if ((dir.exists() || dir.mkdirs()) && dir.canWrite())
99 new DiskTileCacher(inUrl, tileFile, inObserver);
102 return false; // couldn't write the file
106 * Check whether the given tile is already being loaded
107 * @param inFile desired file
108 * @return true if temporary file with this name exists
110 private static boolean isBeingLoaded(File inFile)
112 File tempFile = new File(inFile.getAbsolutePath() + ".temp");
113 return tempFile.exists();
117 * Run method for loading URL asynchronously and saving to file
121 boolean finished = false;
122 InputStream in = null;
123 FileOutputStream out = null;
124 File tempFile = new File(_file.getAbsolutePath() + ".temp");
125 // Use a synchronized block across all threads to make sure this url is only fetched once
126 synchronized (DiskTileCacher.class)
128 if (tempFile.exists()) {return;}
130 if (!tempFile.createNewFile()) {return;}
132 catch (Exception e) {return;}
136 // Open streams from URL and to file
137 out = new FileOutputStream(tempFile);
138 // Set http user agent on connection
139 URLConnection conn = _url.openConnection();
140 conn.setRequestProperty("User-Agent", "GpsPrune v" + GpsPrune.VERSION_NUMBER);
141 in = conn.getInputStream();
143 // Loop over each byte in the stream (maybe buffering is more efficient?)
144 while ((d = in.read()) >= 0) {
148 } catch (IOException e) {
149 System.err.println("ioe: " + e.getClass().getName() + " - " + e.getMessage());
150 BLOCKED_URLS.add(_url.toString());
155 try {in.close();} catch (Exception e) {} // ignore
156 try {out.close();} catch (Exception e) {} // ignore
161 // Move temp file to desired file location
162 if (!tempFile.renameTo(_file))
164 // File couldn't be moved - delete both to be sure
168 // Tell parent that load is finished (parameters ignored)
169 _observer.imageUpdate(null, ImageObserver.ALLBITS, 0, 0, 0, 0);