android - 在 S3 服务器上并行上传图片

Question

我正在使用 TransferUtility 在 Amazon S3 服务器上上传图像。我正在尝试一张一张地上传 3 张图片，但它是并行上传的。我想一张一张上传图片。我应该怎么做？我正在使用以下代码进行上传:

private void uploadToAWS(TransferUtility transferUtility,final ArrayList<File> imageFileArrayList){

    final ArrayList<String> uploadedFileArrayList = new ArrayList<>();
    final ArrayList<String> failedFileArrayList = new ArrayList<>();

    for(int i = 0; i < imageFileArrayList.size(); i++) {

        final File file = imageFileArrayList.get(i);
        final TransferObserver observer = transferUtility.upload(
                Constants.S3_BUCKET_NAME,                /* The bucket to upload to */
                "Test_Images" + file.getAbsolutePath(),  /* The key for the uploaded object */
                file                                     /* The file where the data to upload exists */
        );
        observer.setTransferListener(new TransferListener() {

                @Override
                public void onStateChanged(int id, TransferState state) {
                    System.out.println("Id:- " + id);
                    if (state == TransferState.COMPLETED) {
                        uploadedFileArrayList.add(observer.getAbsoluteFilePath());
                    } else if (state == TransferState.FAILED) {
                        failedFileArrayList.add(file.getAbsolutePath());
                    }
                }

                @Override
                public void onProgressChanged(int id, long bytesCurrent, long bytesTotal) {
                    int percent = (int) ((bytesCurrent * 100) / bytesTotal);
                    System.out.println("percent:- " + percent);
                }

                @Override
                public void onError(int id, Exception ex) {
                    ex.printStackTrace();
                    System.out.println("Id:- " + id + " in exception");
                }
            });

    }

}

我在 Asynctask 中调用这个函数。

@Override                           
protected Void doInBackground(Void... params) {

AmazonS3 amazonS3 = new AmazonS3Client(getAWSCredentials());

TransferUtility transferUtility = new TransferUtility(amazonS3, context);

uploadToAWS(transferUtility, imageFileArrayList);

return null;

}

请帮忙。

Answer 1

好的，问题来了:您正在从 uploadToAWS() 的循环中调用 transferUtility.upload()。现在您调用第一个文件上传但无需等待完成(因为您已将其放入循环中)您遍历循环并调用下一个文件上传，依此类推...

现在要避免这种情况，您需要做的就是等待 TransferState.COMPLETED 事件回调，一旦完成，您应该调用下一个文件上传(通过另一个调用 transferUtility.upload()).

您可能还想添加一些重试代码，以防在 TransferState.FAILED 回调中上传失败。

所以你的代码大致变成这样:

private void uploadToAWS(TransferUtility transferUtility,final ArrayList<File> imageFileArrayList) {

    final File file = imageFileArrayList.get(i);
    final TransferObserver observer = transferUtility.upload(
            Constants.S3_BUCKET_NAME,                /* The bucket to upload to */
            "Test_Images" + file.getAbsolutePath(),  /* The key for the uploaded object */
            file                                     /* The file where the data to upload exists */
    );
    observer.setTransferListener(new TransferListener() {

            @Override
            public void onStateChanged(int id, TransferState state) {
                System.out.println("Id:- " + id);
                if (state == TransferState.COMPLETED) {
                    uploadedFileArrayList.add(observer.getAbsoluteFilePath());

                    failedFileArrayList.remove(file.getAbsolutePath());
                    i++;
                    uploadToAWS(transferUtility, imageFileArrayList);
                } else if (state == TransferState.FAILED) {
                    failedFileArrayList.add(file.getAbsolutePath());
                    uploadToAWS(transferUtility, imageFileArrayList);
                }
            }

            @Override
            public void onProgressChanged(int id, long bytesCurrent, long bytesTotal) {
                int percent = (int) ((bytesCurrent * 100) / bytesTotal);
                System.out.println("percent:- " + percent);
            }

            @Override
            public void onError(int id, Exception ex) {
                failedFileArrayList.add(file.getAbsolutePath());
                ex.printStackTrace();
                System.out.println("Id:- " + id + " in exception");
            }
        });

    }

}

这是您的代码可能的非常粗略的实现。您可能想要更改整个流程，这当然更好。