Add a UriDataSource for reading from file or network.

library/src/main/java/com/google/android/exoplayer/upstream/UriDataSource.java

+/*
+ * Copyright (C) 2014 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.exoplayer.upstream;
+
+import com.google.android.exoplayer.util.Assertions;
+
+import java.io.IOException;
+
+/**
+ * A data source that fetches data from a local or remote {@link DataSpec}.
+ */
+public final class UriDataSource implements DataSource {
+
+  private static final String FILE_URI_SCHEME = "file";
+
+  private final DataSource fileDataSource;
+  private final DataSource httpDataSource;
+
+  /**
+   * {@code null} if no data source is open. Otherwise, equal to {@link #fileDataSource} if the open
+   * data source is a file, or {@link #httpDataSource} otherwise.
+   */
+  private DataSource dataSource;
+
+  /**
+   * Constructs a new data source that delegates to a {@link FileDataSource} for file URIs and an
+   * {@link HttpDataSource} for other URIs.
+   *
+   * @param userAgent The User-Agent string that should be used when requesting remote data.
+   * @param transferListener An optional listener.
+   */
+  public UriDataSource(String userAgent, TransferListener transferListener) {
+    this(new FileDataSource(transferListener),
+        new HttpDataSource(userAgent, null, transferListener));
+  }
+
+  /**
+   * Constructs a new data source using {@code fileDataSource} for file URIs, and
+   * {@code httpDataSource} for non-file URIs.
+   *
+   * @param fileDataSource {@link DataSource} to use for file URIs.
+   * @param httpDataSource {@link DataSource} to use for non-file URIs.
+   */
+  public UriDataSource(DataSource fileDataSource, DataSource httpDataSource) {
+    this.fileDataSource = Assertions.checkNotNull(fileDataSource);
+    this.httpDataSource = Assertions.checkNotNull(httpDataSource);
+  }
+
+  @Override
+  public long open(DataSpec dataSpec) throws IOException {
+    Assertions.checkState(dataSource == null);
+
+    dataSource = dataSpec.uri.getScheme().equals(FILE_URI_SCHEME) ? fileDataSource : httpDataSource;
+    return dataSource.open(dataSpec);
+  }
+
+  @Override
+  public void close() throws IOException {
+    Assertions.checkNotNull(dataSource);
+
+    dataSource.close();
+    dataSource = null;
+  }
+
+  @Override
+  public int read(byte[] buffer, int offset, int readLength) throws IOException {
+    Assertions.checkNotNull(dataSource);
+
+    return dataSource.read(buffer, offset, readLength);
+  }
+
+}