JAVA 访问FTP服务器示例（1）

吴贺华

　　在.NET中访问FTP是比较方便的事情，.NET Framework 类库提供了封装好的类。
　　在java中访问FTP真的是个比较麻烦的事情。
　　网上找了半天的资料，找到了java中封装了一下下的一个包，是apache的。Commons.net包。（下载： org.apache.commons.net）
　　在找资料的时候，找到了人家写好的一个案例，很不错，但是功能不足，这里我就没有自己完全编写了。那人家的代码修改了一下，呵呵，完成功能就OK了。源代码是从哪里搞过来的我都不记得了。这个向那位朋友表示感谢和歉意。
　　原来的代码里面只有上传和下载两个功能，并且支持断点续传，做的非常棒。
　　但是我还需要列举FTP里面的目录和目录下的文件。所以自己编写了这两个功能，代码不多，比较简单。
　　编写好的代码及注释如下：
　　


import java.io.File;
import java.io.IOException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.RandomAccessFile;
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 FtpHelper {
private FTPClient ftpClient = new FTPClient();
/**
* 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);
ftpClient.setControlEncoding("GBK");
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,支持断点续传，上传百分比汇报
*
* @param remote
*            远程文件路径
* @param local
*            本地文件路径
* @return 上传的状态
* @throws IOException
*/
public DownloadStatus download(String remote, String local)
throws IOException {
// 设置被动模式
ftpClient.enterLocalPassiveMode();
// 设置以二进制方式传输
ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
DownloadStatus result;
// 检查远程文件是否存在
FTPFile[] files = ftpClient.listFiles(new String(
remote.getBytes("GBK"), "iso-8859-1"));
if (files.length != 1) {
System.out.println("远程文件不存在");
return DownloadStatus.Remote_File_Noexist;
}
long lRemoteSize = files[0].getSize();
File f = new File(local);
// 本地存在文件，进行断点下载
if (f.exists()) {
long localSize = f.length();
// 判断本地文件大小是否大于远程文件大小
if (localSize >= lRemoteSize) {
System.out.println("本地文件大于远程文件，下载中止");
return DownloadStatus.Local_Bigger_Remote;
}
// 进行断点续传，并记录状态
FileOutputStream out = new FileOutputStream(f, true);
ftpClient.setRestartOffset(localSize);
InputStream in = ftpClient.retrieveFileStream(new String(remote
.getBytes("GBK"), "iso-8859-1"));
byte[] bytes = new byte[1024];
long step = lRemoteSize / 100;
long process = localSize / step;
int c;
while ((c = in.read(bytes)) != -1) {
out.write(bytes, 0, c);
localSize += c;
long nowProcess = localSize / step;
if (nowProcess > process) {
process = nowProcess;
if (process % 10 == 0)
System.out.println("下载进度：" + process);
// TODO 更新文件下载进度,值存放在process变量中
}
}
in.close();
out.close();
boolean isDo = ftpClient.completePendingCommand();
if (isDo) {
result = DownloadStatus.Download_From_Break_Success;
} else {
result = DownloadStatus.Download_From_Break_Failed;
}
} else {
OutputStream out = new FileOutputStream(f);
InputStream in = ftpClient.retrieveFileStream(new String(remote
.getBytes("GBK"), "iso-8859-1"));
byte[] bytes = new byte[1024];
long step = lRemoteSize / 100;
long process = 0;
long localSize = 0L;
int c;
while ((c = in.read(bytes)) != -1) {
out.write(bytes, 0, c);
localSize += c;
long nowProcess = localSize / step;
if (nowProcess > process) {
process = nowProcess;
if (process % 10 == 0)
System.out.println("下载进度：" + process);
// TODO 更新文件下载进度,值存放在process变量中
}
}
in.close();
out.close();
boolean upNewStatus = ftpClient.completePendingCommand();
if (upNewStatus) {
result = DownloadStatus.Download_New_Success;
} else {
result = DownloadStatus.Download_New_Failed;
}
}
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);
ftpClient.setControlEncoding("GBK");
UploadStatus result;
// 对远程目录的处理
String remoteFileName = remote;
if (remote.contains("/")) {
remoteFileName = remote.substring(remote.lastIndexOf("/") + 1);
// 创建服务器远程目录结构，创建失败直接返回
if (createDirecroty(remote, ftpClient) == UploadStatus.Create_Directory_Fail) {
return UploadStatus.Create_Directory_Fail;
}
}
//ftpClient.feat();
//System.out.println( ftpClient.getReply());
//System.out.println( ftpClient.acct(null));
//System.out.println(ftpClient.getReplyCode());
//System.out.println(ftpClient.getReplyString());

// 检查远程是否存在文件
FTPFile[] files = ftpClient.listFiles(new String(remoteFileName
.getBytes("GBK"), "iso-8859-1"));
if (files.length == 1) {
long remoteSize = files[0].getSize();
File f = new File(local);
long localSize = f.length();
if (remoteSize == localSize) { // 文件存在
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
result = uploadFile(remoteFileName, f, ftpClient, remoteSize);
// 如果断点续传没有成功，则删除服务器上文件，重新上传
if (result == UploadStatus.Upload_From_Break_Failed) {
if (!ftpClient.deleteFile(remoteFileName)) {
return UploadStatus.Delete_Remote_Faild;
}
result = uploadFile(remoteFileName, f, ftpClient, 0);
}
} else {
result = uploadFile(remoteFileName, new File(local), ftpClient, 0);
}
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();
}
}
/**
* 递归创建远程服务器目录
*
* @param remote
*            远程服务器文件绝对路径
* @param ftpClient
*            FTPClient对象
* @return 目录创建是否成功
* @throws IOException
*/
public UploadStatus createDirecroty(String remote, FTPClient ftpClient)
throws IOException {
UploadStatus status = UploadStatus.Create_Directory_Success;
String directory = remote.substring(0, remote.lastIndexOf("/") + 1);
if (!directory.equalsIgnoreCase("/")
&& !ftpClient.changeWorkingDirectory(new String(directory
.getBytes("GBK"), "iso-8859-1"))) {
// 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 = new String(remote.substring(start, end)
.getBytes("GBK"), "iso-8859-1");
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  0) {
ftpClient.setRestartOffset(remoteSize);
process = remoteSize / step;
raf.seek(remoteSize);
localreadbytes = remoteSize;
}
byte[] bytes = new byte[1024];
int c;
while ((c = raf.read(bytes)) != -1) {
out.write(bytes, 0, c);
localreadbytes += c;
if (localreadbytes / step != process) {
process = localreadbytes / step;
System.out.println("上传进度:" + process);
// TODO 汇报上传状态
}
}
out.flush();
raf.close();
out.close();
boolean result = ftpClient.completePendingCommand();
if (remoteSize > 0) {
status = result ? UploadStatus.Upload_From_Break_Success
: UploadStatus.Upload_From_Break_Failed;
} else {
status = result ? UploadStatus.Upload_New_File_Success
: UploadStatus.Upload_New_File_Failed;
}
return status;
}
/**
* 获取指定目录下的文件名称列表
* @author HQQW510_64
* @param currentDir 需要获取其子目录的当前目录名称
* @return 返回子目录字符串数组
*/
public String[] GetFileNames(String currentDir) {
String[] dirs = null;
try {
if(currentDir==null)
dirs = ftpClient.listNames();
else
dirs = ftpClient.listNames(currentDir);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return dirs;
}
/**
* 获取指定目录下的文件与目录信息集合
* @param currentDir 指定的当前目录
* @return 返回的文件集合
*/
public FTPFile[] GetDirAndFilesInfo(String currentDir)
{
FTPFile[] files=null;
try
{
if(currentDir==null)
files=ftpClient.listFiles();
else
files = ftpClient.listFiles(currentDir);
}
catch(IOException ex)
{
// TODO Auto-generated catch block
ex.printStackTrace();
}
return files;
}
}