java基于Apache FTP断点续传的文件上传和下载

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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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