java中ftp断点上传功能的实现

d2m9dc94pt

　　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。

package apache.net.test;
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());
}
}
}

　　其中部分代码，如服务器连接，断开，打印命令到控制台等来自于互联网