在Java中使用FTP并检测断开连接

我已使用org.apache.commons.net.ftp.FtpClient创建可以并行下载多个文件并在失败时重试的可靠FTP类。在Java中使用FTP并检测断开连接

奇怪的是，我似乎无法让代码识别失败。例如，如果我在传输过程中拉动以太网电缆，则代码似乎继续阻止：

client.retrieveFile(nextFile, ftpOutputStream);

line。有人能告诉我为什么它会阻止这行，而不是返回false或抛出异常？我错过了设置超时或类似的东西吗？

try { 
    OutputStream ftpOutputStream = new FileOutputStream(fileName); 

    System.out.println("Attempting to retrieve file [" + nextFile + "]."); 
    success = iclient.retrieveFile(nextFile, ftpOutputStream); 
    System.out.println("Returned from retrieving file [" + nextFile + "]."); 

    ftpOutputStream.close(); 
} 

//Can fail due to FTPConnectionClosedException, CopyStreamException, or IOException. In any case, best course 
//of action is to simply create a new connection, log in again, and change back to target directory. 
catch(Exception ex) { 

    try { 
     System.out.println("Error occurred during download, deleting file and restarting."); 
     Thread.sleep(1000); 

     //Delete the failed file assuming any of it got written to the local drive. 
     File f = new File(fileName);       
     if(f.exists()) { 
      System.out.println("Deleting file..."); 
      f.delete(); 
     }    

     Thread.sleep(5000); 
    } 
    catch (InterruptedException iex) { 
     System.out.println("Interrupted exceptoin while respoding to failed FTP attempt."); 
    } 
}

来源

2012-10-01 John Humphreys - w00te

“要解决这个问题的方法是实现自己的SocketFactory与SocketClient.setSocketFactory设置（FTPClient是SocketClient的子类）。当你实现的SocketFactory，加setConnectTimeout方法或一些这样的。里面的createSocket方法，请使用带有超时的J2SE 1.4连接方法。“

请参阅“如何设置连接超时？”问题在Commons Net FAQ 为什么这是如此。

来源

2012-10-01 22:07:27 JohnKlehm

在Java中使用FTP并检测断开连接

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