Question

我正在阅读s3 android指南，我真的很困惑如何下载我的文件。

他们提供此代码：

TransferObserver observer = transferUtility.download(
  MY_BUCKET,     /* The bucket to download from */
  OBJECT_KEY,    /* The key for the object to download */
  MY_FILE        /* The file to download the object to */
);

那么什么是MY_FILE？我想制作一个本地空文件对象并将其提供给transferUtility下载功能，并将该空文件填入一个下载文件？

而且，当我完成文件后，（特别是图像）我如何使用滑翔或毕加索将该文件上传到imageView？

我不确定如何使用TransferObserver对象。

希望有人可以提供一个有效的例子！

喝彩！

Answer 1

虽然我很晚才回答这个问题。希望这可以帮助那些陷入这个问题的人。

您无需公开存储桶。您可以通过Glide直接显示图像。这是我通过Glide从亚马逊s3桶装载图像的回购。

https://github.com/jontyankit/Glide-Amazon-Image-Load

您需要覆盖GlideModule并注册我们的组件

public class CustomGlideModule implements GlideModule {

@Override
public void applyOptions(Context context, GlideBuilder builder) {
    builder.setDecodeFormat(DecodeFormat.PREFER_ARGB_8888);
}

@Override
public void registerComponents(Context context, Glide glide) {
    glide.register(ImageModel.class, InputStream.class, new ImageLoader.Factory());
}
}

制作自定义ModelLoader类。此类基于上述模型而不是URL

来获取图像

 public class ImageLoader implements ModelLoader<ImageModel, InputStream> {

private final ModelCache<ImageModel, ImageModel> mModelCache;

public ImageLoader(ModelCache<ImageModel, ImageModel> mModelCache) {
    this.mModelCache = mModelCache;
}

@Override
public DataFetcher<InputStream> getResourceFetcher(ImageModel model, int width, int height) {
    ImageModel imageModel = model;
    if (mModelCache != null) {
        imageModel = mModelCache.get(model, 0, 0);
        if (imageModel == null) {
            mModelCache.put(model, 0, 0, model);
            imageModel = model;
        }
    }
    return new ImageFetcher(imageModel);
}

public static class Factory implements ModelLoaderFactory<ImageModel, InputStream> {

    private final ModelCache<ImageModel, ImageModel> mModelCache = new ModelCache<>(500);

    @Override
    public ModelLoader<ImageModel, InputStream> build(Context context, GenericLoaderFactory factories) {
        return new ImageLoader(mModelCache);
    }

    @Override
    public void teardown() {

    }
}

}

最后制作自定义类DataFetcher。 public InputStream loadData（优先级优先级）是从亚马逊下载图片的方法。

public class ImageFetcher implements DataFetcher<InputStream> {

private final ImageModel imageModel;
private InputStream mInputStream;
boolean downloadComplete = false;
int transferId = 0;

public ImageFetcher(ImageModel imageModel) {
    this.imageModel = imageModel;
}

@Override
public InputStream loadData(Priority priority) throws Exception {
    return fetchStream(imageModel);
}

private InputStream fetchStream(final ImageModel imageModel) {
    TransferUtility transferUtility = AmazonClient.getClient().getTransferUtility();
    TransferObserver bolomessages = transferUtility.download(imageModel.getBucketName(), imageModel.getId(), new File(imageModel.getLocalPath()));
    transferId = bolomessages.getId();

    bolomessages.setTransferListener(new TransferListener() {

        @Override
        public void onStateChanged(int id, TransferState state) {
            Log.wtf("AWSS3", "onStateChanged = " + state);
            if (state == TransferState.COMPLETED) {
                File initialFile = new File(imageModel.getLocalPath());
                try {
                    mInputStream = new FileInputStream(initialFile);
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                }
                downloadComplete = true;
            }
        }

        @Override
        public void onProgressChanged(int id, long bytesCurrent, long bytesTotal) {
        }

        @Override
        public void onError(int id, Exception ex) {
            // do something
            Log.wtf("AWSS3", "onError");
            ex.printStackTrace();
            downloadComplete = true;
        }
    });
    while (!downloadComplete){}
    return mInputStream;
}

@Override
public void cleanup() {
    if (mInputStream != null) {
        try {
            mInputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            mInputStream = null;
        }
    }
}

@Override
public String getId() {
    return imageModel.getId();
}

@Override
public void cancel() {
    AmazonClient.getClient().getTransferUtility().cancel(transferId);
}
}

Answer 2

因此，我可以使用Glide或picasso使用s3存储桶中图像的url加载图像。但是你必须公开这个桶。

以下是您上传图片的方式：

 Glide.with(getActivity().getBaseContext()).load("IMAGE URL FROM S3").centerCrop().into(cardImage);

感谢@KNeerajLal，您可以在这里公开宣传。这里：

making bucket public

Android - 如何从s3下载图像？

2 个答案: