我从 FTP 服务器下载的文件与服务器上的文件长度不同

Question

我正在 Java 中使用 FTPClient 从服务器下载文件。下载文件后，我想检查它的完整性，然后将其删除。我通过比较下载文件的大小（以字节为单位）和服务器上的文件（以字节为单位）来执行此操作，但是结果并不像预期的那样。

以下是我的传输目录的摘录：

for (int i = 0; i <= insideDirectory.length - 1; i++) {
                    FTPFile transferFile = insideDirectory[i];
                    LOGGER.info("Passing file" + folder.getName() + "/" + transferFile.getName());

                    File downloadFile = new File("/users/home/example" + i + ".mp4");
                    OutputStream outputStream2 = new BufferedOutputStream(new FileOutputStream(downloadFile));
                    System.out.println(transferFile.getSize());
                    ftpClient.enterLocalPassiveMode();
                    ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
                    InputStream inputStream = ftpClient
                            .retrieveFileStream(folder.getName() + "/" + transferFile.getName());
                    byte[] bytesArray = new byte[4096];
                    int bytesRead = -1;
                    while ((bytesRead = inputStream.read(bytesArray)) != -1) {
                        outputStream2.write(bytesArray, 0, bytesRead);
                    }

                    Boolean success = ftpClient.completePendingCommand();
                    if (success) {
                        System.out.println("File #" + i + " has been downloaded successfully.");
                        checkIfExists(downloadFile, transferFile);
                    }

下面是我的checkIfExists方法

public void checkIfExists(File downloadedFile, FTPFile remoteFileToDelete) {
    Long downloadedLength = downloadedFile.length();
    Long remoteLength = remoteFileToDelete.getSize();
    if (downloadedFile.length() == remoteFileToDelete.getSize()) {
        LOGGER.info(downloadedLength + "exists and is the same length as " + remoteLength + ". Let's delete");
    } else {
        LOGGER.info(downloadedLength + "is not the same length as " + remoteLength + ". Let's not delete");
    }
}

这是运行循环两次后的输出，如您所见，下载文件的大小可能会有所不同：

     File #0 has been downloaded successfully.
     INFO: 7596008is not the same length as 7600840. Let's not delete
     File #1 has been downloaded successfully.
     INFO: 6873664is not the same length as 6878544. Let's not delete
     File #2 has been downloaded successfully.
     INFO: 7558112is not the same length as 7564744. Let's not delete
     File #3 has been downloaded successfully.
     INFO: 8662336is not the same length as 8665108. Let's not delete

     File #0 has been downloaded successfully.
     INFO: 7594312is not the same length as 7600840. Let's not delete
     File #1 has been downloaded successfully.
     INFO: 6870392is not the same length as 6878544. Let's not delete
     File #2 has been downloaded successfully.
     INFO: 7559184is not the same length as 7564744. Let's not delete
     File #3 has been downloaded successfully.
     INFO: 8660888is not the same length as 8665108. Let's not delete

Answer 1

.close() 您的 BufferedOutputStream 在您尝试测量写入文件的大小之前。

如果没有 .close()，则无法保证（实际上恰恰相反）您写入流的所有数据实际上都已写入您通过 File对象。

我从 FTP 服务器下载的文件与服务器上的文件长度不同

Files that I download from an FTP server do not have the same length as the files on the server

java

ftp

ftp-client

inputstream

outputstream