JAVA实现FTP断点上传的方法

本文实例讲述了JAVA实现FTP断点上传的方法。分享给大家供大家参考。具体分析如下：

这里主要使用apache中的net包来实现。网址http://commons.apache.org/net/。具体包的下载和API文档请看官网。 断点上传就是在上传的过程中设置传输的起始位置。并设置二进制传输。

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(); 
   public ContinueFTP(){ 
     //设置将过程中使用到的命令输出到控制台 
     this.ftpClient.addProtocolCommandListener(new PrintCommandListener(new PrintWriter(System.out))); 
   } 
    
   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; 
   } 
    
   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; 
   } 
    
   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; 
   } 
    
   public void disconnect() throws IOException{ 
     if(ftpClient.isConnected()){ 
ftpClient.disconnect(); 
     } 
   } 
   public static void main(String[] args) { 
     ContinueFTP myFtp = new ContinueFTP(); 
     try { 
myFtp.connect("192.168.21.171", 21, "test", "test"); 
System.out.println(myFtp.upload("E:\VP6.flv", "/MIS/video/VP6.flv")); 
myFtp.disconnect(); 
     } catch (IOException e) { 
System.out.println("连接FTP出错："+e.getMessage()); 
     } 
   } 
}

希望本文所述对大家的java程序设计有所帮助。