使用FTP4J恢复上传进度，并获得上传的百分比

Question

有任何一个例子，如何上传与ftp4j，支持简历，以及如何显示进度条？

Answer 1

我刚刚实现了一种如下代码。

我发现如果使用压缩流，就不能依赖侦听器报告的传输字节，因为服务器可以等待进一步的数据来解码先前接收的块。

Hovewer，即使流是平原，在某些情况下失去连接时，您仍然不能依赖侦听器报告的总传输字节。因此，我终于意识到最好的方法是问服务器它接收了多少字节。

在我的模板中，时间冗余更普遍，涉及到与FTP服务器的控制连接。您可以将while循环限制在数据连接上，即上传。

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FTPClient ftpClient = null;
long writtenBytes;
boolean isCompletedStartingDelete = false; // Our policy is overwrite at first
for (int attempt = 0; attempt < MAX_ATTEMPTS; attempt++) {
   try {
      ftpClient = getFTPClient();
      configureFtpClient(ftpClient);
      doLogin(ftpClient);  
      ftpClient.changeDirectory(remoteDirectory);

      if (!isCompletedStartingDelete) { // Our policy is overwrite at first
         try {
             ftpClient.deleteFile(file);
             isCompletedStartingDelete = true;
         } catch (FTPException e) {
             // Maybe you should check if this exception is really thrown for file not existing.
             isCompletedStartingDelete = true;
         }
      }

      try { 
         writtenBytes = ftpClient.fileSize(fileName);
      } catch (Exception e) { 
         writtenBytes = 0;
      }

      if (ftpClient.isResumeSupported()) {
         // With this template you also could use APPEND
         ftpClient.upload(file, writtenBytes, listener);
      } else {
         ftpClient.upload(file, listener);
      }  
   } catch (FTPAbortException e) {
      // User Aborted operation
      break;
   } catch (Exception e) {
      if (attempt == MAX_ATTEMPTS) { // Or in general lastLoop
         throw e;
      } else {
         // Mask failure
         // LOG
      }
   } finally {
      if (ftpClient != null && ftpClient.isConnected()) {
         try { ftpClient.disconnect(); } catch (Throwable t) { /* LOG */ } 
   }  
}

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