android ftp 下载有关问题

android ftp 下载问题
package lemote.test.mid.util;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;

import lemote.test.mid.properties.DefaultValue;

import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPClientConfig;
import org.apache.commons.net.ftp.FTPReply;

import android.os.Environment;

public class FtpUnit {
  private FTPClient ftpClient = null;
  private String SDPATH;
  public FtpUnit(){
  SDPATH =Environment.getExternalStorageDirectory()+"/";
  }
   
  /**
  * 连接Ftp服务器
  */
  public void connectServer(){
  if(ftpClient == null){
  int reply;
  try{
  ftpClient = new FTPClient();
  ftpClient.setDefaultPort(21);
  ftpClient.configure(getFtpConfig());
  ftpClient.connect("172.16.18.175");
  ftpClient.login("anonymous","");
  ftpClient.setDefaultPort(21);  
  reply = ftpClient.getReplyCode();
  System.out.println(reply+"----");
  if (!FTPReply.isPositiveCompletion(reply)) {
  ftpClient.disconnect();
  System.err.println("FTP server refused connection.");
  }
  ftpClient.enterLocalPassiveMode();
  ftpClient.setControlEncoding("gbk");
  }catch(Exception e){
  e.printStackTrace();
  }
  }
  }
   
  /**
  * 上传文件
  * @param localFilePath--本地文件路径
  * @param newFileName--新的文件名
  */
  public void uploadFile(String localFilePath,String newFileName){
  connectServer();
  //上传文件
  BufferedInputStream buffIn=null;
  try{
  buffIn=new BufferedInputStream(new FileInputStream(SDPATH+"/"+localFilePath));
  System.out.println(SDPATH+"/"+localFilePath);
  System.out.println("start="+System.currentTimeMillis());
  ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
  ftpClient.storeFile("a1.mp3", buffIn);
  System.out.println("end="+System.currentTimeMillis());
  }catch(Exception e){
  e.printStackTrace();
  }finally{
  try{
  if(buffIn!=null)
  buffIn.close();
  }catch(Exception e){
  e.printStackTrace();
  }
  }
  }
   
  /**
  * 下载文件
  * @param remoteFileName --服务器上的文件名
  * @param localFileName--本地文件名
  */
  public void loadFile(String remoteFileName,String localFileName){
  connectServer();
  System.out.println("==============="+localFileName);
  //下载文件
  BufferedOutputStream buffOut=null;