java - 如何正确关闭FTPClient FileStream

Question

我正在使用 Apache Commons Net 的 FTPClient 从位于服务器上的文件中读取内容。仅读取一次时效果很好。但是当我尝试读取第二个文件时，FTPClient 的 InputStream 返回 null。这是我的代码:

            FTPClient ftpClient = new FTPClient();
            ftpClient.connect("myhostname");
            ftpClient.login("myusername", "mypassword");

            // read InputStream from file
            InputStream inputStream = ftpClient.retrieveFileStream("/my/firstfile.txt");
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));

            // read every line...

            // close everything
            inputStream.close();
            bufferedReader.close();


            // second try
            inputStream = ftpClient.retrieveFileStream("/my/secondfile.txt");
            bufferedReader = new BufferedReader(new InputStreamReader(inputStream));

            // ...
            inputStream.close();
            bufferedReader.close();

我做错了什么？

Answer 1

关闭InputStream后，执行以下操作:

ftpClient.completePendingCommand();

您可以在 javadoc of FTPClient#retrieveFileStream 中找到更多信息:

To finalize the file transfer you must call completePendingCommand and check its return value to verify success. If this is not done, subsequent commands may behave unexpectedly.