java基于Apache FTP点断续传的文件上传和下载

基于Apache FTP实现文件上传下载工具 ，上传文件时需要考虑以下问题（实例是续传功能）：

（1）、 FTP服务器是否存在改目录，如果不存在目录则需要创建目录。

（2）、判断上传文件是否已经存在，如果存在是需要删除后再上传还是续传。

1、上传或下载状态的枚举类：

package com.scengine.wtms.utils.ftp; 

public enum UploadStatus
{
  File_Exits(0), Create_Directory_Success(1), Create_Directory_Fail(2), Upload_From_Break_Success(3), Upload_From_Break_Faild(4), Download_From_Break_Success(5), Download_From_Break_Faild(6), Upload_New_File_Success(7), Upload_New_File_Failed(8), Delete_Remote_Success(9), Delete_Remote_Faild(10),Remote_Bigger_Local(11),Remote_smaller_locall(12); 

  private int status; 

  public int getStatus()
  {
    return status;
  } 

  public void setStatus(int status)
  {
    this.status = status;
  } 

  UploadStatus(int status)
  {
    this.status = status;
  }
}

2、工具类代码：

package com.scengine.wtms.utils.ftp; 

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import org.apache.commons.net.PrintCommandListener;
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPFile;
import org.apache.commons.net.ftp.FTPReply; 

public class ContinueFTP
{ 

  private FTPClient ftpClient = new FTPClient(); 

  /**
   * 对象构造 设置将过程中使用到的命令输出到控制台
   */
  public ContinueFTP()
  {
    this.ftpClient.addProtocolCommandListener(new PrintCommandListener(new PrintWriter(System.out)));
  } 

  /**
   *
   * java编程中用于连接到FTP服务器
   *
   * @param hostname
   *      主机名
   *
   * @param port
   *      端口
   *
   * @param username
   *      用户名
   *
   * @param password
   *      密码
   *
   * @return 是否连接成功
   *
   * @throws IOException
   */ 

  public boolean connect(String hostname, int port, String username, String password) throws IOException
  { 

    ftpClient.connect(hostname, port); 

    if (FTPReply.isPositiveCompletion(ftpClient.getReplyCode()))
    { 

      if (ftpClient.login(username, password))
      {
        return true;
      }
    }
    disconnect();
    return false; 

  } 

  /**
   *
   * 从FTP服务器上下载文件
   *
   * @param remote
   *      远程文件路径
   *
   * @param local
   *      本地文件路径
   *
   * @return 是否成功
   *
   * @throws IOException
   */ 

  @SuppressWarnings("resource")
  public boolean download(String remote, String local) throws IOException
  { 

    ftpClient.enterLocalPassiveMode(); 

    ftpClient.setFileType(FTP.BINARY_FILE_TYPE); 

    boolean result; 

    File f = new File(local); 

    FTPFile[] files = ftpClient.listFiles(remote); 

    if (files.length != 1)
    {
      System.out.println("远程文件不唯一");
      return false;
    } 

    long lRemoteSize = files[0].getSize(); 

    if (f.exists())
    {
      OutputStream out = new FileOutputStream(f, true);
      System.out.println("本地文件大小为:" + f.length()); 

      if (f.length() >= lRemoteSize)
      { 

        System.out.println("本地文件大小大于远程文件大小，下载中止"); 

        return false; 

      } 

      ftpClient.setRestartOffset(f.length()); 

      result = ftpClient.retrieveFile(remote, out); 

      out.close(); 

    } else
    { 

      OutputStream out = new FileOutputStream(f);
      result = ftpClient.retrieveFile(remote, out);
      out.close();
    } 

    return result; 

  } 

  /**
   *
   * 上传文件到FTP服务器，支持断点续传
   *
   * @param local
   *      本地文件名称，绝对路径
   *
   * @param remote
   *      远程文件路径，使用/home/directory1/subdirectory/file.ext
   *      按照Linux上的路径指定方式，支持多级目录嵌套，支持递归创建不存在的目录结构
   *
   * @return 上传结果
   *
   * @throws IOException
   */ 

  @SuppressWarnings("resource")
  public UploadStatus upload(String local, String remote) throws IOException
  { 

    // 设置PassiveMode传输 

    ftpClient.enterLocalPassiveMode(); 

    // 设置以二进制流的方式传输 

    ftpClient.setFileType(FTP.BINARY_FILE_TYPE); 

    UploadStatus result; 

    // 对远程目录的处理 

    String remoteFileName = remote; 

    if (remote.contains("/"))
    { 

      remoteFileName = remote.substring(remote.lastIndexOf("/") + 1); 

      String directory = remote.substring(0, remote.lastIndexOf("/") + 1); 

      if (!directory.equalsIgnoreCase("/") && !ftpClient.changeWorkingDirectory(directory))
      { 

        // 如果远程目录不存在，则递归创建远程服务器目录 

        int start = 0; 

        int end = 0; 

        if (directory.startsWith("/"))
        { 

          start = 1; 

        } else
        { 

          start = 0; 

        } 

        end = directory.indexOf("/", start); 

        while (true)
        { 

          String subDirectory = remote.substring(start, end); 

          if (!ftpClient.changeWorkingDirectory(subDirectory))
          { 

            if (ftpClient.makeDirectory(subDirectory))
            { 

              ftpClient.changeWorkingDirectory(subDirectory); 

            } else
            { 

              System.out.println("创建目录失败"); 

              return UploadStatus.Create_Directory_Fail; 

            } 

          } 

          start = end + 1; 

          end = directory.indexOf("/", start); 

          // 检查所有目录是否创建完毕 

          if (end <= start)
          { 

            break; 

          } 

        } 

      } 

    } 

    // 检查远程是否存在文件 

    FTPFile[] files = ftpClient.listFiles(remoteFileName); 

    if (files.length == 1)
    { 

      long remoteSize = files[0].getSize(); 

      File f = new File(local); 

      long localSize = f.length(); 

      if (remoteSize == localSize)
      { 

        return UploadStatus.File_Exits; 

      } else if (remoteSize > localSize)
      { 

        return UploadStatus.Remote_Bigger_Local; 

      } 

      // 尝试移动文件内读取指针,实现断点续传 

      InputStream is = new FileInputStream(f); 

      if (is.skip(remoteSize) == remoteSize)
      { 

        ftpClient.setRestartOffset(remoteSize); 

        if (ftpClient.storeFile(remote, is))
        { 

          return UploadStatus.Upload_From_Break_Success; 

        } 

      } 

      // 如果断点续传没有成功，则删除服务器上文件，重新上传 

      if (!ftpClient.deleteFile(remoteFileName))
      { 

        return UploadStatus.Delete_Remote_Faild; 

      } 

      is = new FileInputStream(f); 

      if (ftpClient.storeFile(remote, is))
      { 

        result = UploadStatus.Upload_New_File_Success; 

      } else
      { 

        result = UploadStatus.Upload_New_File_Failed; 

      } 

      is.close(); 

    } else
    { 

      InputStream is = new FileInputStream(local); 

      if (ftpClient.storeFile(remoteFileName, is))
      { 

        result = UploadStatus.Upload_New_File_Success; 

      } else
      { 

        result = UploadStatus.Upload_New_File_Failed; 

      } 

      is.close();
    } 

    return result; 

  } 

  /**
   *
   * 断开与远程服务器的连接
   *
   * @throws IOException
   */ 

  public void disconnect() throws IOException
  { 

    if (ftpClient.isConnected())
    {
      ftpClient.disconnect();
    } 

  } 

  public static void main(String[] args)
  {
    ContinueFTP myFtp = new ContinueFTP();
    try
    { 

      myFtp.connect("192.168.1.200", 21, "duser", "HTPDuserXP32"); 

      System.out.println(myFtp.upload("C:\\Users\\Administrator\\Desktop\\swing.drawer.jar", "/jars/swing.drawer.jar")); 

      myFtp.disconnect(); 

    } catch (IOException e)
    { 

      System.out.println("连接FTP出错：" + e.getMessage()); 

    } 

  } 

} 

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