如何在JAVA中使用ftp客户端获取ftp服务器中的十二个最新文件

Question

我想使用FTP客户端读取FTP服务器中的12个十二个最新的XML文件，但是我只得到最新的和最后一个。

public static void main(String[] args) throws IOException
{
  FTPClient client = new FTPClient();
  try
  {
    client.connect(host);
    client.login(user, pwd);
    FTPFile[] files = client.listFiles();
    FTPFile lastFile = lastFileModified(files);
    System.out.println(lastFile.getName());
    client.disconnect();
  }
  catch (SocketException e)
  {
    // TODO Auto-generated catch block
    e.printStackTrace();
  }
  catch (IOException e)
  {
    // TODO Auto-generated catch block
    e.printStackTrace();
  }

}

public static FTPFile lastFileModified(FTPFile[] files)
{
  Date lastMod = files[0].getTimestamp().getTime();
  FTPFile choice = null;
  for (FTPFile file : files)
  {
    if (file.getTimestamp().getTime().after(lastMod))
    {
      choice = file;
      lastMod = file.getTimestamp().getTime();
    }
  }
  return choice;
}

Connection Success
/AGIN/20150616
201506152344.xml
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**/AGIN/20150616
201506170004.xml
/AGIN/20150616  LATEST　XML FILE
201506170004.xml**
/AGIN/lostAndfound/20150616
201506160536.xml
/AGIN/lostAndfound/20150616
201506160552.xml
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Connection close

Answer 1

创建自己的比较器

public class ModifiedComparator implements Comparator<FTPFile> {

  public int compare(FTPFile leftFile, FTPFile rightFile) {
    return leftFile.getTimestamp().compareTo(rightFile.getTimeStamp());
  }
}

从这里你有一个有序列表

您可以从列表中获取最后/前十二个项目。 根据您提供的订单

List<FTPFile> list = Arrays.asList(files);
Collections.sort(list, new ModifiedComparator());

编辑

public class LastModifiedComparator implements Comparator<FTPFile> {

  public int compare(FTPFile leftFile, FTPFile rightFile) {
    return -leftFile.getTimestamp().compareTo(rightFile.getTimeStamp());
  }
}

List<FTPFile> list = Arrays.asList(files);
Collections.sort(list, new LastModifiedComparator());   

您可以使用此方法getLastNoOfFiles(list,12)来返回所需的文件数。

private List<FTPFile> getLastNoOfFiles(List<FTPFile> files, int noOfFilesToGet)
{
  List<FTPFile> latestFiles =  new ArrayList<FTPFile>();

   int index = 1;
  for (FTPFile file : files)
  {
    if (noOfFilesToGet < index)
    {
      break;
    }
    latestFiles.add(file);
    index ++;
  }
  return latestFiles;
}