JAVA实现FTP断点上传的方法

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)));

}

/**

* 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tgmJql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tgmJql，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());

}

}

}

希望本文所述对大家的java程序设计有所帮助。

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