(Chilkat for Android™ API)
Synchronize Local Directory Tree

Downloads files from the FTP server to a local directory tree. Synchronization modes include:

mode=0: Download all files
mode=1: Download all files that do not exist on the local filesystem.
mode=2: Download newer or non-existant files.
mode=3: Download only newer files. If a file does not already exist on the local filesystem, it is not downloaded from the server.

Download: Chilkat for Android™ Java Libraries

// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {
  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    TextView tv = new TextView(this);
    String outStr = "";

    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) {
        outStr += ftp.lastErrorText() + "\n";
        tv.setText(outStr);
        setContentView(tv);
        return;
    }

    //  Note: This is a valid FTP account that you may use for testing.
    ftp.put_Hostname("ftp.secureftp-test.com");
    ftp.put_Username("test");
    ftp.put_Password("test");

    ftp.put_KeepSessionLog(true);

    //  Connect and login to the FTP server.
    success = ftp.Connect();
    if (success != true) {
        outStr += ftp.lastErrorText() + "\n";
        tv.setText(outStr);
        setContentView(tv);
        return;
    }

    //  Set the current remote directory to the root of
    //  the tree to be downloaded.
    success = ftp.ChangeRemoteDir("/subDir1");
    if (success != true) {
        outStr += ftp.lastErrorText() + "\n";
        tv.setText(outStr);
        setContentView(tv);
        return;
    }

    //  Recursively download all non-existant and newer files.
    int mode;
    mode = 2;
    success = ftp.SyncLocalTree("c:/temp/subDir1",mode);
    if (success != true) {
        outStr += ftp.lastErrorText() + "\n";
        tv.setText(outStr);
        setContentView(tv);
        return;
    }

    ftp.Disconnect();

    //  Display the session log.
    outStr += ftp.sessionLog() + "\n";
    tv.setText(outStr);
    setContentView(tv);
  }

  static {
      // Important: Make sure the name passed to loadLibrary matches the shared library
      // found in your project's libs/armeabi directory.
      //  for "libchilkat.so", pass "chilkat" to loadLibrary
      //  for "libchilkatemail.so", pass "chilkatemail" to loadLibrary
      //  etc.
      // 
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}