implement okhttp response caching

based on patch from: Baldur Gudbjornsson <baldur.gudbjornsson@gmail.com>

vtm-tests/test/org/oscim/tiling/source/OkHttpEngineTest.java

@@ -3,6 +3,7 @@ package org.oscim.tiling.source;
 import static org.fest.assertions.api.Assertions.assertThat;
 
 import java.io.BufferedReader;
+import java.io.File;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 
@@ -12,6 +13,7 @@ import org.junit.Test;
 import org.oscim.core.Tile;
 import org.oscim.tiling.source.oscimap4.OSciMap4TileSource;
 
+import com.squareup.okhttp.HttpResponseCache;
 import com.squareup.okhttp.mockwebserver.MockResponse;
 import com.squareup.okhttp.mockwebserver.MockWebServer;
 import com.squareup.okhttp.mockwebserver.RecordedRequest;
@@ -20,6 +22,7 @@ public class OkHttpEngineTest {
 	private OkHttpEngine engine;
 	private MockWebServer server;
 	private MockResponse mockResponse;
+	private HttpResponseCache cache;
 
 	@Before
 	public void setUp() throws Exception {
@@ -87,4 +90,15 @@ public class OkHttpEngineTest {
 		assertThat(engine.requestCompleted(true)).isTrue();
 		assertThat(engine.requestCompleted(false)).isFalse();
 	}
+
+	@Test
+	public void create_shouldUseTileSourceCache() throws Exception {
+		cache = new HttpResponseCache(new File("tmp"), 1024);
+		OSciMap4TileSource tileSource =
+		        new OSciMap4TileSource(server.getUrl("/tiles/vtm").toString());
+		engine = (OkHttpEngine) new OkHttpEngine.OkHttpFactory(cache).create(tileSource);
+		engine.sendRequest(new Tile(1, 2, new Integer(3).byteValue()));
+		engine.requestCompleted(true);
+		assertThat(cache.getRequestCount()).isEqualTo(1);
+	}
 }

vtm/src/org/oscim/tiling/source/OkHttpEngine.java

@@ -27,10 +27,15 @@ import java.util.Map.Entry;
 
 import org.oscim.core.Tile;
 import org.oscim.utils.IOUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
+import com.squareup.okhttp.HttpResponseCache;
 import com.squareup.okhttp.OkHttpClient;
 
 public class OkHttpEngine implements HttpEngine {
+	static final Logger log = LoggerFactory.getLogger(OkHttpEngine.class);
+
 	private final OkHttpClient mClient;
 	private final UrlTileSource mTileSource;
 
@@ -41,6 +46,11 @@ public class OkHttpEngine implements HttpEngine {
 			mClient = new OkHttpClient();
 		}
 
+		public OkHttpFactory(HttpResponseCache responseCache) {
+			mClient = new OkHttpClient();
+			mClient.setResponseCache(responseCache);
+		}
+
 		@Override
 		public HttpEngine create(UrlTileSource tileSource) {
 			return new OkHttpEngine(mClient, tileSource);
@@ -95,7 +105,7 @@ public class OkHttpEngine implements HttpEngine {
 
 	@Override
 	public void setCache(OutputStream os) {
-		// TODO: Evaluate OkHttp response cache and determine if additional caching is required.
+		// OkHttp cache implented through tileSource setResponseCache
 	}
 
 	@Override