public static byte[] getImage(int x, int y, int zoom, HttpMapSource mapSource)
throws IOException, InterruptedException, UnrecoverableDownloadException {
MapSpace mapSpace = mapSource.getMapSpace();
int maxTileIndex = mapSpace.getMaxPixels(zoom) / mapSpace.getTileSize();
if (x > maxTileIndex)
throw new RuntimeException("Invalid tile index x=" + x + " for zoom " + zoom);
if (y > maxTileIndex)
throw new RuntimeException("Invalid tile index y=" + y + " for zoom " + zoom);
TileStore ts = TileStore.getInstance();
// Thread.sleep(2000);
// Test code for creating random download failures
// if (Math.random()>0.7) throw new
// IOException("intentionally download error");
Settings s = Settings.getInstance();
TileStoreEntry tile = null;
if (s.tileStoreEnabled) {
// Copy the file from the persistent tilestore instead of
// downloading it from internet.
tile = ts.getTile(x, y, zoom, mapSource);
boolean expired = isTileExpired(tile);
if (tile != null) {
if (expired) {
log.trace("Expired: " + mapSource.getName() + " " + tile);
} else {
log.trace("Tile of map source " + mapSource.getName() + " used from tilestore");
byte[] data = tile.getData();
notifyCachedTileUsed(data.length);
return data;
}
}
}
byte[] data = null;
if (tile == null) {
data = downloadTileAndUpdateStore(x, y, zoom, mapSource);
notifyTileDownloaded(data.length);
} else {
byte[] updatedData = updateStoredTile(tile, mapSource);
if (updatedData != null) {
data = updatedData;
notifyTileDownloaded(data.length);
} else {
data = tile.getData();
notifyCachedTileUsed(data.length);
}
}
return data;
}
public static boolean isTileExpired(TileStoreEntry tileStoreEntry) {
if (tileStoreEntry == null) return true;
long expiredTime = tileStoreEntry.getTimeExpires();
if (expiredTime >= 0) {
// server had set an expiration time
long maxExpirationTime = settings.tileMaxExpirationTime + tileStoreEntry.getTimeDownloaded();
long minExpirationTime = settings.tileMinExpirationTime + tileStoreEntry.getTimeDownloaded();
expiredTime = Math.max(minExpirationTime, Math.min(maxExpirationTime, expiredTime));
} else {
// no expiration time set by server - use the default one
expiredTime = tileStoreEntry.getTimeDownloaded() + settings.tileDefaultExpirationTime;
}
return (expiredTime < System.currentTimeMillis());
}
protected static boolean hasTileETag(TileStoreEntry tile, HttpMapSource mapSource)
throws IOException {
String eTag = tile.geteTag();
if (eTag == null || eTag.length() == 0) {
log.warn("ETag check not possible: " + "tile in tilestore does not contain ETag attribute");
return true;
}
HttpURLConnection conn =
mapSource.getTileUrlConnection(tile.getZoom(), tile.getX(), tile.getY());
conn.setRequestMethod("HEAD");
conn.setRequestProperty("Accept", ACCEPT);
String onlineETag = conn.getHeaderField("ETag");
if (onlineETag == null || onlineETag.length() == 0) return true;
return (onlineETag.equals(eTag));
}
/**
* Performs a <code>HEAD</code> request for retrieving the <code>LastModified</code> header value.
*/
protected static boolean isTileNewer(TileStoreEntry tile, HttpMapSource mapSource)
throws IOException {
long oldLastModified = tile.getTimeLastModified();
if (oldLastModified <= 0) {
log.warn(
"Tile age comparison not possible: "
+ "tile in tilestore does not contain lastModified attribute");
return true;
}
HttpURLConnection conn =
mapSource.getTileUrlConnection(tile.getZoom(), tile.getX(), tile.getY());
conn.setRequestMethod("HEAD");
conn.setRequestProperty("Accept", ACCEPT);
long newLastModified = conn.getLastModified();
if (newLastModified == 0) return true;
return (newLastModified > oldLastModified);
}
public static byte[] updateStoredTile(TileStoreEntry tile, HttpMapSource mapSource)
throws UnrecoverableDownloadException, IOException, InterruptedException {
final int x = tile.getX();
final int y = tile.getY();
final int zoom = tile.getZoom();
final HttpMapSource.TileUpdate tileUpdate = mapSource.getTileUpdate();
switch (tileUpdate) {
case ETag:
{
boolean unchanged = hasTileETag(tile, mapSource);
if (unchanged) {
if (log.isTraceEnabled())
log.trace("Data unchanged on server (eTag): " + mapSource + " " + tile);
return null;
}
break;
}
case LastModified:
{
boolean isNewer = isTileNewer(tile, mapSource);
if (!isNewer) {
if (log.isTraceEnabled())
log.trace("Data unchanged on server (LastModified): " + mapSource + " " + tile);
return null;
}
break;
}
}
HttpURLConnection conn = mapSource.getTileUrlConnection(zoom, x, y);
if (conn == null)
throw new UnrecoverableDownloadException(
"Tile x="
+ x
+ " y="
+ y
+ " zoom="
+ zoom
+ " is not a valid tile in map source "
+ mapSource);
if (log.isTraceEnabled()) log.trace(String.format("Checking %s %s", mapSource.getName(), tile));
prepareConnection(conn);
boolean conditionalRequest = false;
switch (tileUpdate) {
case IfNoneMatch:
{
if (tile.geteTag() != null) {
conn.setRequestProperty("If-None-Match", tile.geteTag());
conditionalRequest = true;
}
break;
}
case IfModifiedSince:
{
if (tile.getTimeLastModified() > 0) {
conn.setIfModifiedSince(tile.getTimeLastModified());
conditionalRequest = true;
}
break;
}
}
conn.connect();
Settings s = Settings.getInstance();
int code = conn.getResponseCode();
if (conditionalRequest && code == HttpURLConnection.HTTP_NOT_MODIFIED) {
// Data unchanged on server
if (s.tileStoreEnabled) {
tile.update(conn.getExpiration());
TileStore.getInstance().putTile(tile, mapSource);
}
if (log.isTraceEnabled()) log.trace("Data unchanged on server: " + mapSource + " " + tile);
return null;
}
byte[] data = loadBodyDataInBuffer(conn);
if (code != HttpURLConnection.HTTP_OK) throw new DownloadFailedException(conn, code);
checkContentType(conn, data);
checkContentLength(conn, data);
String eTag = conn.getHeaderField("ETag");
long timeLastModified = conn.getLastModified();
long timeExpires = conn.getExpiration();
Utilities.checkForInterruption();
TileImageType imageType = Utilities.getImageType(data);
if (imageType == null)
throw new UnrecoverableDownloadException("The returned image is of unknown format");
if (s.tileStoreEnabled) {
TileStore.getInstance()
.putTileData(data, x, y, zoom, mapSource, timeLastModified, timeExpires, eTag);
}
Utilities.checkForInterruption();
return data;
}