java - 为文件传输分配新的byte []时，如何防止OutOfMemory错误？

Question

我试图读取文件以便通过Wear App发送文件，但出现了OutOfMemory异常。

File file = new File(filePath);
final FileInputStream fileInputStream = new FileInputStream(file);
byte fileContent[] = new byte[(int) file.length()]; //***BOMBS HERE***
fileInputStream.read(fileContent);
fileInputStream.close();
Asset programDataAsset = Asset.createFromBytes(fileContent);

异常指出以下内容：

java.lang.OutOfMemoryError: Failed to allocate a 31150467 byte allocation with 2097152 free bytes and 16MB until OOM
       at com.rithmio.coach.wear.TransferService.sendAssetToMobile(TransferService.java:110)
       at com.rithmio.coach.wear.TransferService.onHandleIntent(TransferService.java:84)
       at com.rithmio.coach.wear.TransferService$1.run(TransferService.java:60)
       at java.lang.Thread.run(Thread.java:818)

Answer 1

让我们使用ChannelApi解决此问题。我们也不必担心我在评论中说过的内容。 Google考虑周全，并提出了一种方便的文件发送方法。 public abstract PendingResult sendFile (GoogleApiClient client, Uri uri)

private String pickBestNodeId(List<Node> nodes) {
    String bestNodeId = null;
    // Find a nearby node or pick one arbitrarily
    for (Node node : nodes) {
        if (node.isNearby()) {
            return node.getId();
         }
         bestNodeId = node.getId();
    }
    return bestNodeId;
}

public boolean send(File f) {
    GoogleApiClient mGoogleApiClient = new GoogleApiClient.Builder(this)
    // Request access only to the Wearable API
        .addApi(Wearable.API)
        .build();
    mGoogleApiClient.blockingConnect();
    Channel channel = openChannel(mGoogleApiClient, pickBestNodeId(Wearable.NodeApi.getConnectedNodes(mGoogleApiClient).await()), "/your/arbitrary/application/specific/path/").await(); //NOTE THE PATH IS ARBITRARY, IT CAN BE WHATEVER YOU WANT. IT DOES NOT POINT TO ANYTHING, AND CAN EVEN BE LEFT WITH WHAT I HAVE.
    boolean didSend = channel.sendFile(mGoogleApiClient, f.toURI()).await().isSuccess();
    channel.close(mGoogleApiClient);
    mGoogleApiClient.disconnect();
    return didSend;
}

注意：这使用阻塞方法，并且不应在ui线程中运行。

如果您希望这些调用是非阻塞的，则应省略我对 PendingResult.await()的使用，并将结果回调设置为 PendingResult。可以通过 setResultCallback(ResultCallback callback)设置回调。