X-Git-Url: http://gitweb.fperrin.net/?p=GpsPrune.git;a=blobdiff_plain;f=src%2Ftim%2Fprune%2Ffunction%2Fsrtm%2FTileDownloader.java;fp=src%2Ftim%2Fprune%2Ffunction%2Fsrtm%2FTileDownloader.java;h=831d4ddecb566a457f8caff7a3b7e84226cc4e25;hp=0000000000000000000000000000000000000000;hb=38a0c12649e9104d0d40ce93a932b9086011f8c8;hpb=8b20e3e027058cdf6ff52993ee5576193d08667a

diff --git a/src/tim/prune/function/srtm/TileDownloader.java b/src/tim/prune/function/srtm/TileDownloader.java
new file mode 100644
index 0000000..831d4dd
--- /dev/null
+++ b/src/tim/prune/function/srtm/TileDownloader.java
@@ -0,0 +1,107 @@
+package tim.prune.function.srtm;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+import java.net.URLConnection;
+
+import tim.prune.GpsPrune;
+import tim.prune.config.Config;
+
+/**
+ * Class to provide a download function for the Space Shuttle's SRTM data files.
+ * HGT files are downloaded into memory via HTTP and stored in the map cache.
+ */
+public class TileDownloader
+{
+	/** Possible results of the download */
+	public enum Result {DOWNLOADED, NOTHING_TO_DO, DOWNLOAD_FAILED, CACHE_FAILED};
+
+	/**
+	 * Download a single tile of SRTM data
+	 * @param inUrl remote URL to get
+	 */
+	public Result downloadTile(URL inUrl)
+	{
+		if (inUrl == null) {
+			return Result.NOTHING_TO_DO;
+		}
+
+		// Check the cache is ok
+		final String diskCachePath = Config.getConfigString(Config.KEY_DISK_CACHE);
+		if (diskCachePath != null)
+		{
+			File srtmDir = new File(diskCachePath, "srtm");
+			if (srtmDir.exists() && !srtmDir.isDirectory()) {
+				// exists but isn't a directory - can't be used
+				return Result.CACHE_FAILED;
+			}
+			if (!srtmDir.exists() && !srtmDir.mkdir()) {
+				// can't create the srtm directory
+				return Result.CACHE_FAILED;
+			}
+		}
+		else {
+			// no cache set up
+			return Result.CACHE_FAILED;
+		}
+
+		// Define streams
+		FileOutputStream outStream = null;
+		InputStream inStream = null;
+		Result result = Result.NOTHING_TO_DO;
+		try
+		{
+			// See if we've already got this tile or not
+			File outputFile = getFileToWrite(inUrl);
+			if (outputFile != null)
+			{
+				System.out.println("Download: Need to download: " + inUrl);
+				outStream = new FileOutputStream(outputFile);
+				URLConnection conn = inUrl.openConnection();
+				conn.setRequestProperty("User-Agent", "GpsPrune v" + GpsPrune.VERSION_NUMBER);
+				inStream = conn.getInputStream();
+				// Copy all the bytes to the file
+				int c;
+				while ((c = inStream.read()) != -1)
+				{
+					outStream.write(c);
+				}
+				result = Result.DOWNLOADED;
+			}
+		}
+		catch (IOException ioe) {
+			System.err.println(ioe.getClass().getName() + " - " + ioe.getMessage());
+			result = Result.DOWNLOAD_FAILED;
+		}
+		// Make sure streams are closed
+		try {inStream.close();} catch (Exception e) {}
+		try {outStream.close();} catch (Exception e) {}
+
+		return result;
+	}
+
+	/**
+	 * See whether the SRTM file is already available locally
+	 * @param inUrl URL for online resource
+	 * @return file object to write to, or null if already there
+	 */
+	private static File getFileToWrite(URL inUrl)
+	{
+		String diskCachePath = Config.getConfigString(Config.KEY_DISK_CACHE);
+		if (diskCachePath != null)
+		{
+			File srtmDir = new File(diskCachePath, "srtm");
+			if (srtmDir.exists() && srtmDir.isDirectory() && srtmDir.canRead())
+			{
+				File srtmFile = new File(srtmDir, new File(inUrl.getFile()).getName());
+				if (!srtmFile.exists() || !srtmFile.canRead() || srtmFile.length() <= 400) {
+					return srtmFile;
+				}
+			}
+		}
+		return null;
+	}
+}