Restart/Resume FTP Download

Resume downloading a file from an FTP server.

Download Chilkat Java Library

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    CkFtp2 ftp = new CkFtp2();

    boolean success;

    //  Any string unlocks the component for the 1st 30-days.
    success = ftp.UnlockComponent("Anything for 30-day trial");
    if (success != true) {
        System.out.println(ftp.lastErrorText());
        return;
    }

    ftp.put_Hostname("ftp.chilkatsoft.com");
    ftp.put_Username("****");
    ftp.put_Password("****");

    //  Connect and login to the FTP server.
    success = ftp.Connect();
    if (success != true) {
        System.out.println(ftp.lastErrorText());
        return;
    }

    //  Change to the remote directory where the file is located.
    //  This step is only necessary if the file is not in the root directory
    //  for the FTP account.
    success = ftp.ChangeRemoteDir("temp");
    if (success != true) {
        System.out.println(ftp.lastErrorText());
        return;
    }

    //  To resume a download, it is assumed that the partial file
    //  is already present on the local filesystem.
    //  You only need to set the RestartNext property to resume
    //  the download.  The Chilkat FTP component sets the resume
    //  point by getting the existing size of the target (local) file.
    ftp.put_RestartNext(true);

    String localFilename;
    localFilename = "big.zip";
    String remoteFilename;
    remoteFilename = "big.zip";

    //  Resume downloading...
    success = ftp.GetFile(remoteFilename,localFilename);
    if (success != true) {
        System.out.println(ftp.lastErrorText());
        return;
    }

    ftp.Disconnect();

    System.out.println("File Downloaded!");
  }
}