Allow ByteArrayDataSource to resolve the byte array when opened

This is a relatively small change, and massively simplifies the work
needed for an app to consume Kotlin Multiplatform resources (without a
full `KmpResourceDataSource` implementation, which poses some
dependency challenges for now).

Issue: androidx/media#1405
PiperOrigin-RevId: 638991375

RELEASENOTES.md

@@ -145,6 +145,10 @@
     *   Add support for non-square DASH thumbnail grids
         ([#1300](https://github.com/androidx/media/pull/1300)).
     *   Add support for AVIF for API 34+.
+*   DataSource:
+    *   Allow `ByteArrayDataSource` to resolve a URI to a byte array during
+        `open()`, instead of being hard-coded at construction
+        ([#1405](https://github.com/androidx/media/issues/1405)).
 *   DRM:
     *   Allow setting a `LoadErrorHandlingPolicy` on
         `DefaultDrmSessionManagerProvider`

libraries/datasource/src/main/java/androidx/media3/datasource/ByteArrayDataSource.java

@@ -15,13 +15,15 @@
  */
 package androidx.media3.datasource;
 
+import static androidx.media3.common.util.Assertions.checkArgument;
+import static androidx.media3.common.util.Assertions.checkNotNull;
+import static androidx.media3.common.util.Assertions.checkStateNotNull;
 import static java.lang.Math.min;
 
 import android.net.Uri;
 import androidx.annotation.Nullable;
 import androidx.media3.common.C;
 import androidx.media3.common.PlaybackException;
-import androidx.media3.common.util.Assertions;
 import androidx.media3.common.util.UnstableApi;
 import java.io.IOException;
 
@@ -29,27 +31,55 @@ import java.io.IOException;
 @UnstableApi
 public final class ByteArrayDataSource extends BaseDataSource {
 
-  private final byte[] data;
+  /** Functional interface to resolve from {@link Uri} to {@link byte[]}. */
+  public interface UriResolver {
+    /**
+     * Resolves a {@link Uri} to a {@link byte[]}.
+     *
+     * <p>Called during {@link DataSource#open(DataSpec)} from a loading thread, so can do blocking
+     * work.
+     *
+     * @return The resolved byte array.
+     * @throws IOException if the provided URI is not recognized, or an error occurs during
+     *     resolution.
+     */
+    byte[] resolve(Uri uri) throws IOException;
+  }
+
+  private final UriResolver uriResolver;
 
   @Nullable private Uri uri;
+  @Nullable private byte[] data;
   private int readPosition;
   private int bytesRemaining;
   private boolean opened;
 
   /**
+   * Creates an instance.
+   *
    * @param data The data to be read.
    */
   public ByteArrayDataSource(byte[] data) {
+    this(/* uriResolver= */ unusedUri -> data);
+    checkArgument(data.length > 0);
+  }
+
+  /**
+   * Creates an instance.
+   *
+   * @param uriResolver Function to resolve from {@link Uri} to {@link byte[]} during {@link
+   *     #open(DataSpec)}.
+   */
+  public ByteArrayDataSource(UriResolver uriResolver) {
     super(/* isNetwork= */ false);
-    Assertions.checkNotNull(data);
+    this.uriResolver = checkNotNull(uriResolver);
-    Assertions.checkArgument(data.length > 0);
-    this.data = data;
   }
 
   @Override
   public long open(DataSpec dataSpec) throws IOException {
-    uri = dataSpec.uri;
     transferInitializing(dataSpec);
+    uri = dataSpec.uri;
+    data = uriResolver.resolve(uri);
     if (dataSpec.position > data.length) {
       throw new DataSourceException(PlaybackException.ERROR_CODE_IO_READ_POSITION_OUT_OF_RANGE);
     }
@@ -72,7 +102,7 @@ public final class ByteArrayDataSource extends BaseDataSource {
     }
 
     length = min(length, bytesRemaining);
-    System.arraycopy(data, readPosition, buffer, offset, length);
+    System.arraycopy(checkStateNotNull(data), readPosition, buffer, offset, length);
     readPosition += length;
     bytesRemaining -= length;
     bytesTransferred(length);
@@ -92,5 +122,6 @@ public final class ByteArrayDataSource extends BaseDataSource {
       transferEnded();
     }
     uri = null;
+    data = null;
   }
 }

libraries/datasource/src/test/java/androidx/media3/datasource/ByteArrayDataSourceContractTest.java

@@ -20,53 +20,45 @@ import androidx.media3.test.utils.DataSourceContractTest;
 import androidx.media3.test.utils.TestUtil;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import com.google.common.collect.ImmutableList;
-import org.junit.Ignore;
+import java.io.IOException;
-import org.junit.Test;
 import org.junit.runner.RunWith;
 
 /** {@link DataSource} contract tests for {@link ByteArrayDataSource}. */
 @RunWith(AndroidJUnit4.class)
 public class ByteArrayDataSourceContractTest extends DataSourceContractTest {
 
-  private static final byte[] DATA = TestUtil.buildTestData(20);
+  private static final Uri URI_1 = Uri.parse("uri1");
+  private static final byte[] DATA_1 = TestUtil.buildTestData(20);
+  private static final Uri URI_2 = Uri.parse("uri2");
+  private static final byte[] DATA_2 = TestUtil.buildTestData(10);
 
   @Override
   protected ImmutableList<TestResource> getTestResources() {
     return ImmutableList.of(
+        new TestResource.Builder().setName("data-1").setUri(URI_1).setExpectedBytes(DATA_1).build(),
         new TestResource.Builder()
-            .setName("simple")
+            .setName("data-2")
-            .setUri(Uri.EMPTY)
+            .setUri(URI_2)
-            .setExpectedBytes(DATA)
+            .setExpectedBytes(DATA_2)
             .build());
   }
 
   @Override
   protected Uri getNotFoundUri() {
-    throw new UnsupportedOperationException();
+    return Uri.parse("not-found");
   }
 
   @Override
   protected DataSource createDataSource() {
-    return new ByteArrayDataSource(DATA);
+    return new ByteArrayDataSource(
+        uri -> {
+          if (uri.equals(URI_1)) {
+            return DATA_1;
+          } else if (uri.equals(URI_2)) {
+            return DATA_2;
+          } else {
+            throw new IOException("Unrecognized URI: " + uri);
+          }
+        });
   }
-
-  @Override
-  @Test
-  @Ignore
-  public void resourceNotFound() {}
-
-  @Override
-  @Test
-  @Ignore
-  public void resourceNotFound_transferListenerCallbacks() {}
-
-  @Override
-  @Test
-  @Ignore
-  public void getUri_resourceNotFound_returnsNullIfNotOpened() throws Exception {}
-
-  @Override
-  @Test
-  @Ignore
-  public void getResponseHeaders_resourceNotFound_isEmptyWhileNotOpen() throws Exception {}
 }