java终实现ftp断点上传

   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))); 
     } 
      
     /**
      * 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
      */ 
     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
      */ 
     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("192.168.21.171", 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()); 
         } 
     } 
 }