[NET-717] FTPClient: Encapsulate completePendingCommand in returned outputstream

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: FTP
• Assignee: Unassigned
• Reporter: Julien Béti
• Created: 29/Nov/22 16:34
• Updated: 01/Dec/22 16:47

Description

Most store / retrieve methods in FTPClient class requires a call to completePendingCommand method in order to make sure that the operation completed successfully, and allow additional operations to go on.

This is clearly documented, but often lead to clumsy code as 99% of the time we just need to know if the file operation executed successfully or not (and in some case, the completePendingCommand is simply forgotten leading to, as documented, unexpected behavior of subsequent commands.

The idea would be to return a FilterOutputStream / FilterInputStream that would encapsulates the returned OutputStream/InputStream returned by methods that need a subsequent call to completePendingCommand. These filter implementations would call the completePendingCommand method on close, throwing an IOException if it returns false.

package org.apache.commons.net.ftp;

import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;

public class FTPOutputStream extends FilterOutputStream {
  private final FTPClient ftpClient;
  public FTPOutputStream(OutputStream out, FTPClient ftpClient) {
    super(out);
    this.ftpClient = ftpClient;
  }

  @Override
  public void close() throws IOException {
    super.close();
    if(!ftpClient.completePendingCommand()) {
      throw new IOException("FTP Client was unable to complete pending command");
    }
  }
}

Issue Links

• links to: Pull request