Android FTP 下载 pause/resume

Question

我正在开发一个 Android 项目，需要 FTP 下载 paused/resumed。

这是我用于 FTP 连接的代码：

ftpClient.setConnectTimeout(25000);
ftpClient.login("login", "password");
ftpClient.changeWorkingDirectory("/audio");
ftpClient.enterLocalPassiveMode();
ftpClient.setFileType(FTP.BINARY_FILE_TYPE);

那我开始下载：

OutputStream outputStream = new BufferedOutputStream(new FileOutputStream(localFile));

byte[] bytesArray = new byte[4096];
int bytesRead = -1;
totalRead = 0;

if (localFileSize > 0) {
    ftpClient.setRestartOffset(localFileSize);
    ftpClient.restart(localFileSize);
}

InputStream inputStream = ftpClient.retrieveFileStream(fileName);

while ((bytesRead = inputStream.read(bytesArray)) != -1) {
    totalRead += bytesRead;
    outputStream.write(bytesArray, (int) localFileSize, bytesRead);
}

success = ftpClient.completePendingCommand();

我尝试像这样使用 abort 暂停：

if (ftpClient.abort()) {
   //connection aborted!;
}

但似乎 abort 在有活动下载时不起作用，如下所述：https://issues.apache.org/jira/browse/NET-419

有什么方法可以在 Android 中执行 pause/resume 下载 FTP 吗？

Answer 1

如果您真的只想暂停下载（与 abort/reconnect/resume 相反），那么您需要做的就是暂时暂停写入数据连接流的 while 循环。

见How to pause/resume thread in Android?

Answer 2

我使用相同的 AsyncTask 进行连接、下载和中止操作：

protected Void doInBackground(Integer... params) {
   int command = params.length > 0 ? params[0] : 0;
   switch (command) {
   case CONNECT:
       connect();
       break;
   case DOWNLOAD:
       download();
       break;
   case PAUSE:
       abortConnection();
       break;
    }
    return null;
}

每次使用单例设计模式

确保只有一个任务运行

public static FtpConnectTask getInstance(FTPClientWrapper ftpClient) {
   if (instance != null) {
      if (instance.getStatus().name().toLowerCase().equals("running"){
         instance.cancel(true);
      }
      if (instance.getStatus().name().toLowerCase().equals("finished")) {
          // task finished!
      }
   }
   instance = new FtpConnect(uiListener, ftpClientW);
   return instance;
}

这是download()方法的代码：

we look for local file size each time the download starts, then we use this size as starting point

//create local file
File localFile = new File(outDir, FILE_NAME));
// get file size if the file exists
long localFileSize = localFile.length();   
//retrieve file from server
try {
  OutputStream outputStream = new BufferedOutputStream(new FileOutputStream(localFile, true));
  byte[] bytesArray = new byte[4096];
  int bytesRead;
  int totalRead = (int) localFileSize;
  ftpClient.restart(localFileSize);
  InputStream inputStream = ftpClient.retrieveFileStream(REMOTE_FILE);

  while ((bytesRead = inputStream.read(bytesArray)) != -1) {
     totalRead += bytesRead;
     outputStream.write(bytesArray, 0, bytesRead);
  // break the loop when AsyncTask is cancelled
     if(isCancelled()){
        break;
     }
  }
  if (ftpClient.completePendingCommand()) {
     // Task completed!
  }

  inputStream.close();
  outputStream.close();
} catch (IOException e) {
   e.printStackTrace();
}

这是abortConnection()

的代码

if (ftpClient.isConnected()) {
   try {
      if (ftpClient.abort()) {
         // Connection aborted!
      }
   } catch (IOException e) {
      e.printStackTrace();
   }
} else {
   // Not connected!
}

To resume your download just call download() again.

Android FTP 下载 pause/resume

Android FTP download pause/resume

java

ftp

android

download

apache-commons-net