Apache Commons FTPClient がハングする 質問する

次の Apache Commons Net FTP コードを使用して、FTP サーバーに接続し、いくつかのディレクトリでファイルをポーリングし、ファイルが見つかった場合は、それらをローカル マシンに取得します。

try {
logger.trace("Attempting to connect to server...");

// Connect to server
FTPClient ftpClient = new FTPClient();
ftpClient.setConnectTimeout(20000);
ftpClient.connect("my-server-host-name");
ftpClient.login("myUser", "myPswd");
ftpClient.changeWorkingDirectory("/loadables/");

// Check for failed connection
if(!FTPReply.isPositiveCompletion(ftpClient.getReplyCode()))
{
    ftpClient.disconnect();
    throw new FTPConnectionClosedException("Unable to connect to FTP server.");
}

// Log success msg
logger.trace("...connection was successful.");

// Change to the loadables/ directory where we poll for files
ftpClient.changeWorkingDirectory("/loadables/");    

// Indicate we're about to poll
logger.trace("About to check loadables/ for files...");

// Poll for files.
FTPFile[] filesList = oFTP.listFiles();
for(FTPFile tmpFile : filesList)
{
    if(tmpFile.isDirectory())
        continue;

    FileOutputStream fileOut = new FileOutputStream(new File("tmp"));
    ftpClient.retrieveFile(tmpFile.getName(), fileOut);
    // ... Doing a bunch of things with output stream
    // to copy the contents of the file down to the local
    // machine. Ommitted for brevity but I assure you this
    // works (except when the WAR decides to hang).
    //
    // This was used because FTPClient doesn't appear to GET
    // whole copies of the files, only FTPFiles which seem like
    // file metadata...
}

// Indicate file fetch completed.
logger.trace("File fetch completed.");

// Disconnect and finish.
if(ftpClient.isConnected())
    ftpClient.disconnect();

logger.trace("Poll completed.");
} catch(Throwable t) {
    logger.trace("Error: " + t.getMessage());
}