diff --git a/library/core/src/main/java/com/google/android/exoplayer2/source/offline/Downloader.java b/library/core/src/main/java/com/google/android/exoplayer2/source/offline/Downloader.java
new file mode 100644
index 0000000000..04735551cd
--- /dev/null
+++ b/library/core/src/main/java/com/google/android/exoplayer2/source/offline/Downloader.java
@@ -0,0 +1,195 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.source.offline;
+
+import android.support.annotation.Nullable;
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.upstream.DataSink;
+import com.google.android.exoplayer2.upstream.DataSource;
+import com.google.android.exoplayer2.upstream.DummyDataSource;
+import com.google.android.exoplayer2.upstream.FileDataSource;
+import com.google.android.exoplayer2.upstream.PriorityDataSource;
+import com.google.android.exoplayer2.upstream.cache.Cache;
+import com.google.android.exoplayer2.upstream.cache.CacheDataSink;
+import com.google.android.exoplayer2.upstream.cache.CacheDataSource;
+import com.google.android.exoplayer2.util.ClosedSource;
+import com.google.android.exoplayer2.util.PriorityTaskManager;
+import java.io.IOException;
+
+/**
+ * Base class for stream downloaders.
+ *
+ *
All of the methods are blocking. Also they are not thread safe, except {@link
+ * #getTotalSegments()}, {@link #getDownloadedSegments()} and {@link #getDownloadedBytes()}.
+ *
+ * @param The type of the manifest object.
+ * @param The type of the representation key object.
+ */
+@ClosedSource(reason = "Not ready yet")
+public abstract class Downloader {
+
+ /**
+ * Listener notified when download progresses.
+ */
+ public interface ProgressListener {
+ /**
+ * Called for the first time after the initialization and then after download of each segment.
+ * It is called on the thread which invoked {@link #downloadRepresentations(ProgressListener)}.
+ *
+ * @param downloader The reporting instance.
+ * @param totalSegments Total number of segments in the content.
+ * @param downloadedSegments Total number of downloaded segments.
+ * @param downloadedBytes Total number of downloaded bytes.
+ * @see #downloadRepresentations(ProgressListener)
+ */
+ void onDownloadProgress(Downloader, ?> downloader, int totalSegments,
+ int downloadedSegments, long downloadedBytes);
+ }
+
+ protected final Cache cache;
+ protected final CacheDataSource dataSource;
+ protected final CacheDataSource offlineDataSource;
+ protected final PriorityTaskManager priorityTaskManager;
+ protected final String manifestUri;
+
+ protected volatile int totalSegments;
+ protected volatile int downloadedSegments;
+ protected volatile long downloadedBytes;
+
+ /**
+ * Constructs a Downloader.
+ *
+ * @param manifestUri The URI of the manifest to be downloaded.
+ * @param cache Cache instance to be used to store downloaded data.
+ * @param upstreamDataSource A {@link DataSource} for downloading data.
+ * @param cacheReadDataSource A {@link DataSource} for reading data from the cache.
+ * If null, a {@link FileDataSource} instance is created and used.
+ * @param cacheWriteDataSink A {@link DataSink} for writing data to the cache. If
+ * null, a {@link CacheDataSink} instance is created and used.
+ * @param priorityTaskManager If not null it's used to check whether it is allowed to proceed with
+ * download. Downloader priority is {@link C#PRIORITY_DOWNLOAD}.
+ */
+ public Downloader(String manifestUri, Cache cache, DataSource upstreamDataSource,
+ @Nullable DataSource cacheReadDataSource, @Nullable DataSink cacheWriteDataSink,
+ @Nullable PriorityTaskManager priorityTaskManager) {
+ if (priorityTaskManager != null) {
+ upstreamDataSource =
+ new PriorityDataSource(upstreamDataSource, priorityTaskManager, C.PRIORITY_DOWNLOAD);
+ } else {
+ priorityTaskManager = new PriorityTaskManager(); // dummy PriorityTaskManager
+ }
+ if (cacheReadDataSource == null) {
+ cacheReadDataSource = new FileDataSource();
+ }
+ if (cacheWriteDataSink == null) {
+ cacheWriteDataSink = new CacheDataSink(cache,
+ CacheDataSource.DEFAULT_MAX_CACHE_FILE_SIZE);
+ }
+
+ this.manifestUri = manifestUri;
+ this.cache = cache;
+ this.dataSource = new CacheDataSource(cache, upstreamDataSource, cacheReadDataSource,
+ cacheWriteDataSink, CacheDataSource.FLAG_BLOCK_ON_CACHE, null);
+ this.offlineDataSource = new CacheDataSource(cache, DummyDataSource.INSTANCE,
+ cacheReadDataSource, null, CacheDataSource.FLAG_BLOCK_ON_CACHE, null);
+ this.priorityTaskManager = priorityTaskManager;
+
+ resetCounters();
+ }
+
+ /**
+ * Downloads the manifest.
+ *
+ * @return The downloaded manifest.
+ * @throws IOException If an error occurs reading data from the stream.
+ */
+ public abstract M downloadManifest() throws IOException;
+
+ /**
+ * Selects multiple representations pointed to by the keys for downloading, removing or checking
+ * status. Any previous selection is cleared.
+ */
+ public abstract void selectRepresentations(K... keys);
+
+ /**
+ * Initializes the total segments, downloaded segments and downloaded bytes counters for the
+ * selected representations.
+ *
+ * @throws IOException Thrown when there is an error while reading from cache.
+ * @throws DownloaderException Thrown when a representation index is unbounded.
+ * @throws InterruptedException If the thread has been interrupted.
+ * @see #getTotalSegments()
+ * @see #getDownloadedSegments()
+ * @see #getDownloadedBytes()
+ */
+ public abstract void initStatus() throws DownloaderException, InterruptedException, IOException;
+
+ /**
+ * Downloads the content for the selected representations in sync or resumes a previously stopped
+ * download.
+ *
+ * @throws IOException Thrown when there is an error while downloading.
+ * @throws DownloaderException Thrown when no index data can be found for a representation or
+ * the index is unbounded.
+ * @throws InterruptedException If the thread has been interrupted.
+ */
+ public abstract void downloadRepresentations(@Nullable ProgressListener listener)
+ throws IOException, DownloaderException, InterruptedException;
+
+ /**
+ * Returns the total number of segments in the representations which are selected, or {@link
+ * C#LENGTH_UNSET} if it hasn't been calculated yet.
+ *
+ * @see #initStatus()
+ */
+ public final int getTotalSegments() {
+ return totalSegments;
+ }
+
+ /**
+ * Returns the total number of downloaded segments in the representations which are selected, or
+ * {@link C#LENGTH_UNSET} if it hasn't been calculated yet.
+ *
+ * @see #initStatus()
+ */
+ public final int getDownloadedSegments() {
+ return downloadedSegments;
+ }
+
+ /**
+ * Returns the total number of downloaded bytes in the representations which are selected, or
+ * {@link C#LENGTH_UNSET} if it hasn't been calculated yet.
+ *
+ * @see #initStatus()
+ */
+ public final long getDownloadedBytes() {
+ return downloadedBytes;
+ }
+
+ /**
+ * Removes all representations declared in the manifest and the manifest itself.
+ *
+ * @throws InterruptedException Thrown if the thread was interrupted.
+ */
+ public abstract void removeAll() throws InterruptedException;
+
+ protected final void resetCounters() {
+ totalSegments = C.LENGTH_UNSET;
+ downloadedSegments = C.LENGTH_UNSET;
+ downloadedBytes = C.LENGTH_UNSET;
+ }
+
+}
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/source/offline/DownloaderException.java b/library/core/src/main/java/com/google/android/exoplayer2/source/offline/DownloaderException.java
new file mode 100644
index 0000000000..c07565b721
--- /dev/null
+++ b/library/core/src/main/java/com/google/android/exoplayer2/source/offline/DownloaderException.java
@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.source.offline;
+
+import com.google.android.exoplayer2.util.ClosedSource;
+
+/** Thrown on an error in {@link Downloader}. */
+@ClosedSource(reason = "Not ready yet")
+public final class DownloaderException extends Exception {
+
+ public DownloaderException(String message) {
+ super(message);
+ }
+
+}