我正在使用 Java 将多个文件上传到 Amazon S3。

我使用的代码如下:

MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request;
MultiValueMap < String,
MultipartFile > map = multipartRequest.getMultiFileMap();
try {
    if (map != null) {
        for (String filename: map.keySet()) {
            List < MultipartFile > fileList = map.get(filename);
            incrPercentge = 100 / fileList.size();
            request.getSession().setAttribute("incrPercentge", incrPercentge);
            for (MultipartFile mpf: fileList) {

                /*
         * custom input stream wrap to original input stream to get
         * the progress
         */
                ProgressInputStream inputStream = new ProgressInputStream("test", mpf.getInputStream(), mpf.getBytes().length);
                ObjectMetadata metadata = new ObjectMetadata();
                metadata.setContentType(mpf.getContentType());
                String key = Util.getLoginUserName() + "/" + mpf.getOriginalFilename();
                PutObjectRequest putObjectRequest = new PutObjectRequest(
                Constants.S3_BUCKET_NAME, key, inputStream, metadata).withStorageClass(StorageClass.ReducedRedundancy);
                PutObjectResult response = s3Client.putObject(putObjectRequest);

            }
        }
    }
} catch(Exception e) {
    e.printStackTrace();
}

我必须创建自定义输入流以获取 Amazon S3 使用的字节数。我从这里的问题中得到了这个想法:Upload file or InputStream to S3 with a progress callback

我的ProgressInputStream类代码如下:

package com.spectralnetworks.net.util;
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;
    }

    /**
     * This is on reserach to show a progress bar
     * @param name
     * @param progress
     * @param lastUpdate
     * @param size
     * @return
     */
    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();
        }*/
        System.out.println("name " + name + "  progress " + progress + " lastUpdate " + lastUpdate + " " + "sie " + size);
        return lastUpdate;
    }
}

但这不能正常工作。它立即打印到文件大小如下:

name test  progress 4096 lastUpdate 0 sie 30489
name test  progress 8192 lastUpdate 0 sie 30489
name test  progress 12288 lastUpdate 0 sie 30489
name test  progress 16384 lastUpdate 0 sie 30489
name test  progress 20480 lastUpdate 0 sie 30489
name test  progress 24576 lastUpdate 0 sie 30489
name test  progress 28672 lastUpdate 0 sie 30489
name test  progress 30489 lastUpdate 0 sie 30489
name test  progress 30489 lastUpdate 0 sie 30489

而且实际上传需要更多时间(打印行后超过 10 次)。

我应该怎么做才能获得真实的上传状态？

最佳答案

我得到了问题的答案，这是通过使用以下代码获得真实进度状态的最佳方式

ObjectMetadata metadata = new ObjectMetadata();
metadata.setContentType(mpf.getContentType());

String key = Util.getLoginUserName() + "/"
        + mpf.getOriginalFilename();
metadata.setContentLength(mpf.getSize());
PutObjectRequest putObjectRequest = new PutObjectRequest(
                Constants.S3_BUCKET_NAME, key, mpf.getInputStream(),
                metadata)
        .withStorageClass(StorageClass.ReducedRedundancy);

putObjectRequest.setProgressListener(new ProgressListener() {
        @Override
        public void progressChanged(ProgressEvent progressEvent) {
            System.out.println(progressEvent
                    .getBytesTransfered()
                    + ">> Number of byte transfered "
                    + new Date());
            progressEvent.getBytesTransfered();
            double totalByteRead = request
                    .getSession().getAttribute(
                                                    Constants.TOTAL_BYTE_READ) != null ? (Double) request
                                            .getSession().getAttribute(Constants.TOTAL_BYTE_READ) : 0;

            totalByteRead += progressEvent.getBytesTransfered();
            request.getSession().setAttribute(Constants.TOTAL_BYTE_READ, totalByteRead);
            System.out.println("total Byte read "+ totalByteRead);

            request.getSession().setAttribute(Constants.TOTAL_PROGRESS, (totalByteRead/size)*100);
        System.out.println("percentage completed >>>"+ (totalByteRead/size)*100);   
        if (progressEvent.getEventCode() == ProgressEvent.COMPLETED_EVENT_CODE) {
            System.out.println("completed  ******");
        }
    }
});
s3Client.putObject(putObjectRequest);

我以前的代码的问题是，我没有在元数据中设置内容长度，所以我没有得到真正的进度状态。下面一行是从 PutObjectRequest 类 API 复制的

构造一个新的 PutObjectRequest 对象以将数据流上传到指定的桶和键。构建请求后，用户可以选择指定对象元数据或固定 ACL。

数据流的内容长度必须在对象元数据参数中指定； Amazon S3 要求在上传数据之前传入它。未能指定内容长度将导致输入流的全部内容在内存中进行本地缓冲，以便可以计算内容长度，这可能会导致负面的性能问题。

关于java - 如何使用Java获取上传到Amazon S3的文件的进度状态，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/11908385/