2017-10-09 169 views
1

我正在使用Java中的FTPClient從服務器下載文件。當文件被下載時,我想檢查它的完整性,然後刪除它。 我這樣做是通過比較下載的文件(以字節爲單位)和服務器上的文件(以字節爲單位)的大小來實現的,但結果與預期不符。我從FTP服務器下載的文件長度與服務器上的文件長度不相同

下面是從我的傳輸目錄的摘錄:

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("https://stackoverflow.com/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"); 
    } 
} 

這裏是輸出運行循環兩次之後,你可以看到,大小下載的文件可能有所不同:

 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 
+0

我該如何檢查? – steam1234322

+0

底部的輸出是否不夠?它比較兩個文件的字節大小 – steam1234322

+0

啊,我明白了。然後Alnitak發現了它。 –

回答

3

.close()您的BufferedOutputStream,然後再嘗試測量寫入文件的大小。

如果沒有.close(),則無法保證(實際上恰恰相反)您寫入流中的所有數據實際上都將寫入通過File對象訪問的基礎文件。

+0

好的,你在哪裏推薦我關閉outputStream2? – steam1234322

+0

在測量文件的大小之前。在您修改文件的過程中,檢查文件的大小有什麼好處? –

+2

更確切地說,就在你的'while'循環之後。 –