Apache Commons Net FTP正在上传损坏的文件

Question

我正在尝试使用Apache Commons Net进行FTP文件传输。

问题是文件间歇性到达服务器损坏。 “损坏”是指WinRAR告诉我一个ZIP文件具有'意外的存档末尾'。有时文件是完全空的。我注意到，这种情况在较大的文件（100kb +）上发生的更多，但是在较小的文件（20kb）上也会发生。

我知道正在上传的源zip文件是有效的，并且只有243kb。

我没有从代码中得到任何错误/异常。

这是正在执行的代码：

int CON_TIMEOUT = (int) TimeUnit.SECONDS.toMillis(20); // fail if can't connect within 20 seconds
int LIVE_TIMEOUT = (int) TimeUnit.MINUTES.toMillis(5); // allow up to 5 minutes for data transfers

FTPClient client = new FTPClient();
client.setConnectTimeout(CON_TIMEOUT);
client.setDataTimeout(LIVE_TIMEOUT);
client.connect(host);
client.setSoTimeout(LIVE_TIMEOUT);
client.login(user, pass);
client.changeWorkingDirectory(dir);
log("client ready");

File file = new File(filePath);
String name = new Date().getTime() + "-" + file.getName();

InputStream fis = null;
try
{
    fis = new FileInputStream(file);
    if (!client.storeFile(name, fis))
        throw new RuntimeException("store failed");
    log("store " + name + " complete");
}
finally
{
    IOUtils.closeQuietly(fis);
    try
    {
        client.logout();
        log("logout");
    }
    catch (Throwable e)
    {
        log("logout failed", e);
    }
    try
    {
        client.disconnect();
        log("disconnect");
    }
    catch (Throwable e)
    {
        log("disconnect failed", e);
    }
}

和一些日志：

2010-08-10 21:32:38 client ready
2010-08-10 21:32:49 store 1281439958234-file.zip complete
2010-08-10 21:32:49 logout
2010-08-10 21:32:49 disconnect
2010-08-10 21:32:50 client ready
2010-08-10 21:33:00 store 1281439970968-file.zip complete
2010-08-10 21:33:00 logout
2010-08-10 21:33:00 disconnect
2010-08-10 21:33:02 client ready
2010-08-10 21:33:11 store 1281439982234-file.zip complete
2010-08-10 21:33:11 logout
2010-08-10 21:33:11 disconnect
2010-08-10 21:33:15 client ready
2010-08-10 21:33:25 store 1281439995890-file.zip complete
2010-08-10 21:33:26 logout
2010-08-10 21:33:26 disconnect
2010-08-10 21:33:27 client ready
2010-08-10 21:33:36 store 1281440007531-file.zip complete
2010-08-10 21:33:36 logout
2010-08-10 21:33:36 disconnect
2010-08-10 21:33:37 client ready
2010-08-10 21:33:48 store 1281440017843-file.zip complete
2010-08-10 21:33:48 logout
2010-08-10 21:33:48 disconnect
2010-08-10 21:33:49 client ready
2010-08-10 21:33:59 store 1281440029781-file.zip complete
2010-08-10 21:33:59 logout
2010-08-10 21:33:59 disconnect
2010-08-10 21:34:00 client ready
2010-08-10 21:34:09 store 1281440040812-file.zip complete
2010-08-10 21:34:09 logout
2010-08-10 21:34:09 disconnect
2010-08-10 21:34:10 client ready
2010-08-10 21:34:23 store 1281440050859-file.zip complete
2010-08-10 21:34:24 logout
2010-08-10 21:34:24 disconnect
2010-08-10 21:34:25 client ready
2010-08-10 21:34:35 store 1281440065421-file.zip complete
2010-08-10 21:34:35 logout
2010-08-10 21:34:35 disconnect

请注意，所有这些操作均在15秒内完成，并且服务器上的所有结果文件均已损坏。

我也进行了测试，未设置任何超时，问题仍然存在。

Answer 1

Common FTP默认为Ascii文件类型。在处理二进制数据（例如ZIP文件）时，您希望将其设置为Binary。

来自http://commons.apache.org/net/api/org/apache/commons/net/ftp/FTPClient.html

FTPClient的默认设置是使用FTP.ASCII_FILE_TYPE，FTP.NON_PRINT_TEXT_FORMAT，FTP.STREAM_TRANSFER_MODE和FTP.FILE_STRUCTURE。直接支持的唯一文件类型是FTP.ASCII_FILE_TYPE和FTP.BINARY_FILE_TYPE。

您要在发送文件之前执行setFileType(FTP.BINARY_FILE_TYPE)。

Answer 2

尽管指定了binary file type，但我还是遇到了这个问题，因此我编写了代码以通过MD5哈希验证上传的文件：

public void upload(String sourceFilePath) throws Exception
{
    while (true)
    {
        // Upload
        File sourceFile = new File(sourceFilePath);
        String sourceFileHash = MD5Checksum.getMD5Checksum(sourceFilePath);
        String remoteFile = sourceFile.getName();

        try (InputStream inputStream = new FileInputStream(sourceFile))
        {
            boolean successful = ftpClient.storeFile(remoteFile, inputStream);

            if (!successful)
            {
                throw new IllegalStateException("Upload of " + sourceFilePath + " failed!");
            }
        }

        // Download
        File temporaryFile = File.createTempFile("prefix", "suffix");
        try (OutputStream outputStream = new BufferedOutputStream(new FileOutputStream(temporaryFile)))
        {
            boolean successful = ftpClient.retrieveFile(remoteFile, outputStream);

            if (!successful)
            {
                throw new IllegalStateException("Download of " + sourceFilePath + " failed!");
            }
        }

        String downloadFileHash = MD5Checksum.getMD5Checksum(temporaryFile.getAbsolutePath());
        Files.delete(temporaryFile.toPath());

        // Make sure the file hashes match
        if (sourceFileHash.equals(downloadFileHash))
        {
            break;
        }
    }
}

MD5Checksum.java：

import java.io.*;
import java.security.MessageDigest;

public class MD5Checksum
{
    private static byte[] createChecksum(String filename) throws Exception
    {
        try (InputStream fileInputStream = new FileInputStream(filename))
        {
            byte[] buffer = new byte[1024];
            MessageDigest complete = MessageDigest.getInstance("MD5");
            int numRead;

            do
            {
                numRead = fileInputStream.read(buffer);
                if (numRead > 0)
                {
                    complete.update(buffer, 0, numRead);
                }
            } while (numRead != -1);

            return complete.digest();
        }
    }

    public static String getMD5Checksum(String filename) throws Exception
    {
        byte[] checksum = createChecksum(filename);
        StringBuilder result = new StringBuilder();

        for (byte singleByte : checksum)
        {
            result.append(Integer.toString((singleByte & 0xff) + 0x100, 16).substring(1));
        }

        return result.toString();
    }
}

MD5代码取自here。