使用进度回调将文件或InputStream上载到S3

Question

我们正在使用Amazon AWS Java库上载文件，并且很难获得上载进度。我们目前正在致电以下内容：

File file = new File(localAsset.getVideoFilePath());
PutObjectRequest putObjectRequest = new PutObjectRequest(bucket, localAsset.getFileName(), file);
s3.putObject(putObjectRequest);

我们如何设置回调以检查文件上传进度？

谢谢

Answer 1

我遇到了这个确切的问题，并编写了一个简单的InputStream包装器，该包装器输出了不错的进度条：

import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.vfs.FileContent;
import org.apache.commons.vfs.FileSystemException;

public class ProgressInputStream extends InputStream {
    private final long size;
    private long progress, lastUpdate = 0;
    private final InputStream inputStream;
    private final String name;
    private boolean closed = false;

    public ProgressInputStream(String name, InputStream inputStream, long size) {
        this.size = size;
        this.inputStream = inputStream;
        this.name = name;
    }

    public ProgressInputStream(String name, FileContent content)
    throws FileSystemException {
        this.size = content.getSize();
        this.name = name;
        this.inputStream = content.getInputStream();
    }

    @Override
    public void close() throws IOException {
        super.close();
        if (closed) throw new IOException("already closed");
        closed = true;
    }

    @Override
    public int read() throws IOException {
        int count = inputStream.read();
        if (count > 0)
            progress += count;
        lastUpdate = maybeUpdateDisplay(name, progress, lastUpdate, size);
        return count;
    }
    @Override
    public int read(byte[] b, int off, int len) throws IOException {
        int count = inputStream.read(b, off, len);
        if (count > 0)
            progress += count;
        lastUpdate = maybeUpdateDisplay(name, progress, lastUpdate, size);
        return count;
    }

    static long maybeUpdateDisplay(String name, long progress, long lastUpdate, long size) {
        if (Config.isInUnitTests()) return lastUpdate;
        if (size < B_IN_MB/10) return lastUpdate;
        if (progress - lastUpdate > 1024 * 10) {
            lastUpdate = progress;
            int hashes = (int) (((double)progress / (double)size) * 40);
            if (hashes > 40) hashes = 40;
            String bar = StringUtils.repeat("#",
                    hashes);
            bar = StringUtils.rightPad(bar, 40);
            System.out.format("%s [%s] %.2fMB/%.2fMB\r",
                    name, bar, progress / B_IN_MB, size / B_IN_MB);
            System.out.flush();
        }
        return lastUpdate;
    }
}

（这是从实时代码中复制粘贴的，因此您可能必须做一些修补才能使其在您自己的代码中起作用。）

然后，只需使用InputStream放置内容的方式（确保指定大小！），它将为您提供一个不错的进度条。如果您想要适当的回调，那也很容易做到。