JAVA实现FTP断点上传详解编程语言

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)));   
     }   
 
     /**  
      * 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  
      */   
     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());   
         }   
     }   
 }